SETO Mayumi

researchmap

Profile and Settings

• Name (Japanese)

  Seto

• Name (Kana)

  Mayumi

Degree

• Doctor of Science, Kyushu University

Research Interests

• 個体群動態
• 熱力学
• 数理生物学
• 微生物生態系
• 化学合成微生物

Research Areas

• Nanotechnology/Materials, Inorganic and coordination chemistry
• Environmental science/Agricultural science, Environmental effects of chemicals
• Environmental science/Agricultural science, Environmental effects of radiation
• Environmental science/Agricultural science, Environmental policy and society
• Environmental science/Agricultural science, Environmental impact assessment
• Life sciences, Ecology and environmental science

Research Experience

• Apr. 2009, Mar. 2010, 独立行政法人国立環境研究所, ＮＩＥＳ特別研究員, Japan
• Apr. 2008, Mar. 2009, Ehime University, 沿岸環境科学研究センター, グローバルＣＯＥ研究員, Japan

Education

• 2008, Kyushu University, 理学府, 地球惑星科学科, Japan
• 2008, Kyushu University, Graduate School of Sciences, Department of Earth and Plantary Sciences

Teaching Experience

• Apr. 2016, 9999
• 2016, 9999
• Apr. 2020, 9999
• Apr. 2018, 9999
• Apr. 2018, 9999
• 2018, 9999
• Apr. 2016, 9999
• Apr. 2016, 9999
• 2016, 9999
• 2016, 9999
• Apr. 2016, Mar. 2020
• Apr. 2012, Mar. 2019
• 2012, 2019
• Aug. 2018, Aug. 2018
• Apr. 2018
• Apr. 2022, 9999
• Apr. 2022, 9999
• Apr. 2021, Mar. 2022

Association Memberships

• 日本数理生物学会
• 日本生態学会
• 日本地球化学会

Media Coverage

• 奈良女大 環境トークバトルゲーム, 毎日新聞奈良版, 17 Sep. 2018, 大和のオススメ！

Ⅱ．研究活動実績

Published Papers

• Refereed, Mar. 2023, 16, 1, 12, 10.1007/s12080-022-00550-0
• Refereed, Proceedings of the Royal Society B: Biological Sciences, The Royal Society, Microbial material cycling, energetic constraints and ecosystem expansion in subsurface ecosystems, Mayumi Seto; Yoh Iwasa, To harvest energy from chemical reactions, microbes engage in diverse catabolic interactions that drive material cycles in the environment. Here, we consider a simple mathematical model for cycling reactions between alternative forms of an element (A and A _e ), where reaction 1 converts A to A _e and reaction 2 converts A _e to A. There are two types of microbes: type 1 microbes harness reaction 1, and type 2 microbes harness reaction 2. Each type receives its own catabolic resources from the other type and provides the other type with the by-products as the catabolic resources. Analyses of the model show that each type increases its steady-state abundance in the presence of the other type. The flux of material flow becomes faster in the presence of microbes. By coupling two catabolic reactions, types 1 and 2 can also expand their realized niches through the abundant resource premium, the effect of relative quantities of products and reactants on the available chemical energy, which is especially important for microbes under strong energetic limitations. The plausibility of mutually beneficial interactions is controlled by the available chemical energy (Gibbs energy) of the system. We conclude that mutualistic catabolic interactions can be an important factor that enables microbes in subsurface ecosystems to increase ecosystem productivity and expand the ecosystem., 29 Jul. 2020, 287, 1931, 20200610, 20200610, Scientific journal, 10.1098/rspb.2020.0610

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• Refereed, Ecology Letters, Wiley, The fitness of chemotrophs increases when their catabolic by‐products are consumed by other species, Mayumi Seto; Yoh Iwasa, Chemotrophic microorganisms synthesise biomass by utilising energy obtained from a set of chemical reactions that convert resources to by-products, forming catabolic interactions. The amount of energy obtained per catabolic reaction decreases with the abundance of the by-product named as the ‘abundant resource premium’. Consider two species, Species 1 and 2, Species 1 obtains energy from a reaction that converts resource A to by-product B. Species 2 then utilises B as its resource, extracting energy from a reaction that converts B to C. Thus, the presence of Species 2 reduces the abundance of B, which improves the fitness of Species 1 by increasing the energy acquisition per reaction of A to B. We discuss the population dynamic implication of this effect and its importance in expanding a realised niche, boosting material flow through the ecosystem and providing mutualistic interactions among species linked by the material flow. Introducing thermodynamics into population ecology could offer us fundamental ecological insights into understanding the ecology of chemotrophic microorganisms dominating the subsurface realm., Dec. 2019, 22, 12, 1994, 2005, Scientific journal, 10.1111/ele.13397

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• Refereed, ASTROBIOLOGY, Potential for Aerobic Methanotrophic Metabolism on Mars, Seto Mayumi; Noguchi Katsuyuki; Van Cappellen Philippe, Observational evidence supports the presence of methane (CH4) in the martian atmosphere on the order of parts per billion by volume (ppbv). Here, we assess whether aerobic methanotrophy is a potentially viable metabolism in the martian upper regolith, by calculating metabolic energy gain rates under assumed conditions of martian surface temperature, pressure, and atmospheric composition. Using kinetic parameters for 19 terrestrial aerobic methanotrophic strains, we show that even under the imposed low temperature and pressure extremes (180-280 K and 6-11 hPa), methane oxidation by oxygen (O2) should in principle be able to generate the minimum energy production rate required to support endogenous metabolism (i.e., cellular maintenance). Our results further indicate that the corresponding metabolic activity would be extremely low, with cell doubling times in excess of 4000 Earth years at the present-day ppbv-level CH4 mixing ratios in the atmosphere of Mars. Thus, while aerobic methanotrophic microorganisms similar to those found on Earth could theoretically maintain their vital functions, they are unlikely to constitute prolific members of hypothetical martian soil communities., 07 Jun. 2019, 19, 10, 1187, 1195, Scientific journal, 10.1089/ast.2018.1943

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• Refereed, JOURNAL OF THEORETICAL BIOLOGY, ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, Population dynamics of chemotrophs in anaerobic conditions where the metabolic energy acquisition per redox reaction is limited, Seto Mayumi; Iwasa Yoh, We present a new model of microbial population growth that focuses on the acquisition of metabolic energy through chemosynthesis and how this depends on the concentration of resources and byproducts. Due to entropy effects, organisms extract the greater energy (i.e., they produce the greater amount of adenosine triphosphate) when they use resources that are abundant and generates byproducts that are rare. This effect, which we call the "abundant resource premium," has been neglected in traditional models of microbial growth because the total metabolic energy acquisition is generally far greater than this premium. This term, however, cannot be neglected for many microbes, such as sulfate reducers, iron oxidizers, and methanogens, which live under conditions of low-energy availability. Our model showed qualitatively different behaviors from those observed in traditional microbial population growth models, such as the Monod model. For example, the steady-state population density was maximum at an intermediate resource-utilizing ability, suggesting that high substrate acquisition is not always advantageous for a microbial population when the availability of metabolic energy is low. We discuss possible implications for evolutionary and ecosystem sciences. (C) 2019 Elsevier Ltd. All rights reserved., 21 Apr. 2019, 467, 164, 173, Scientific journal, 10.1016/j.jtbi.2019.01.037

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• Not Refereed, Risk Analysis, Blackwell Publishing Inc., Assessment of Instructions on Protection Against Food Contaminated with Radiocesium in Japan in 2011, Mayumi Seto; Koichiro Uriu; Isao Kawaguchi; Hiroyuki Yokomizo, The Japan Ministry of Health, Labour and Welfare (MHLW) has published instructions for radiological protection against food after the Fukushima Daiichi nuclear power plant accident in 2011. Following the instructions, the export and consumption of food items identified as being contaminated were restricted for a certain period. We assessed the validity of the imposed restriction periods for two representative vegetables (spinach and cabbage) grown in Fukushima Prefecture from two perspectives: effectiveness for reducing dietary dose and economic efficiency. To assess effectiveness, we estimated the restriction period required to maintain consumers’ dose below the guidance dose levels. To assess economic efficiency, we estimated the restriction period that maximizes the net benefit to taxpayers. All estimated restriction periods were shorter than the actual restriction periods imposed on spinach and cabbage from Fukushima in 2011, which indicates that the food restriction effectively maintained consumers’ dietary dose below the guidance dose level, but in an economically inefficient manner. We also evaluated the response of the restriction period to the sample size for each weekly food safety test and the instructions for when to remove the restriction. Stringent MHLW instructions seemed to sufficiently reduce consumers’ health risk even when the sample size for the weekly food safety test was small, but tended to increase the economic cost to taxpayers., 01 Jun. 2018, 38, 6, 1154, 1168, Scientific journal, 10.1111/risa.12893

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• Not Refereed, 地球化学, 化学合成細菌と物質フロー：生物地球化学と生態学の交差点, 瀨戸 繭美, 2017, 51, 4, 185, 193, 10.14934/chikyukagaku.51.185

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• Refereed, ECOLOGICAL INDICATORS, ELSEVIER SCIENCE BV, Perspectives for ecosystem management based on ecosystem resilience and ecological thresholds against multiple and stochastic disturbances, Takehiro Sasaki; Takuya Furukawa; Yuichi Iwasaki; Mayumi Seto; Akira S. Mori, Ecosystem resilience is the inherent ability to absorb various disturbances and reorganize while undergoing state changes to maintain critical functions. When ecosystem resilience is sufficiently degraded by disturbances, ecosystem is exposed at high risk of shifting from a desirable state to an undesirable state. Ecological thresholds represent the points where even small changes in environmental conditions associated with disturbances lead to switch between ecosystem states. There is a growing body of empirical evidence for such state transitions caused by anthropogenic disturbances in a variety of ecosystems. However, fewer studies addressed the interaction of anthropogenic and natural disturbances that often force an ecosystem to cross a threshold which an anthropogenic disturbance or a natural disturbance alone would not have achieved. This fact highlights how little is known about ecosystem dynamics under uncertainties around multiple and stochastic disturbances. Here, we present two perspectives for providing a predictive scientific basis to the management and conservation of ecosystems against multiple and stochastic disturbances. The first is management of predictable anthropogenic disturbances to maintain a sufficient level of biodiversity for ensuring ecosystem resilience (i.e., resilience-based management). Several biological diversity elements appear to confer ecosystem resilience, such as functional redundancy, response diversity, a dominant species, a foundation species, or a keystone species. The greatest research challenge is to identify key elements of biodiversity conferring ecosystem resilience for each context and to examine how we can manage and conserve them. The second is the identification of ecological thresholds along existing or experimental disturbance gradients. This will facilitate the development of indicators of proximity to thresholds as well as the understanding of threshold mechanisms. The implementation of forewarning indicators will be critical particularly when resilience-based management fails. The ability to detect an ecological threshold along disturbance gradients should therefore be essential to establish a backstop for preventing the threshold from being crossed. These perspectives can take us beyond simply invoking the precautionary principle of conserving biodiversity to a predictive science that informs practical solutions to cope with uncertainties and ecological surprises in a changing world. (C) 2015 Elsevier Ltd. All rights reserved., Oct. 2015, 57, 395, 408, 10.1016/j.ecolind.2015.05.019

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• Refereed, RISK ANALYSIS, WILEY-BLACKWELL, Sample Size Allocation for Food Item Radiation Monitoring and Safety Inspection, Mayumi Seto; Koichiro Uriu, The objective of this study is to identify a procedure for determining sample size allocation for food radiation inspections of more than one food item to minimize the potential risk to consumers of internal radiation exposure. We consider a simplified case of food radiation monitoring and safety inspection in which a risk manager is required to monitor two food items, milk and spinach, in a contaminated area. Three protocols for food radiation monitoring with different sample size allocations were assessed by simulating random sampling and inspections of milk and spinach in a conceptual monitoring site. Distributions of I-131 and radiocesium concentrations were determined in reference to I-131 and radiocesium concentrations detected in Fukushima prefecture, Japan, for March and April 2011. The results of the simulations suggested that a protocol that allocates sample size to milk and spinach based on the estimation of I-131 and radiocesium concentrations using the apparent decay rate constants sequentially calculated from past monitoring data can most effectively minimize the potential risks of internal radiation exposure., Mar. 2015, 35, 3, 409, 422, Scientific journal, 10.1111/risa.12276

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• Refereed, GEOMICROBIOLOGY JOURNAL, TAYLOR & FRANCIS INC, The Gibbs Free Energy Threshold for the Invasion of a Microbial Population Under Kinetic Constraints, Mayumi Seto, Possible chemotrophic metabolism at a site of interest is controlled not only by the catabolic energy expressed as the Gibbs energy of reaction (Delta(r)G) but also by the kinetic constraints due to the availability of electron acceptors and donors. We introduced graphical and stochastic approaches for determining the Delta(r)G threshold required to support a microbial population with a specific catabolic strategy under kinetic constraints. Invasibility as an indicator of the present reproductive ability of a microbial population was evaluated by simultaneously calculating Delta(r)G for the catabolic reaction and the microbial catalytic rate. For example, the neutrophilic iron-oxidizing bacteria's invasibility was calculated by randomly choosing the Fe2+ and O-2 concentrations between 10(-8) and 10(-2) mol L-1, and pH between 4 and 8, to determine the Delta(r)G threshold for invasion. Parameters were estimated from batch experiments of neutrophilic iron-oxidizing bacteria reported in previous studies. Under the given conditions, the stochastic approach predicted that the neutrophilic iron-oxidizing bacteria can always invade a system in which the Delta(r)G for Fe oxidation is below -90 kJ mol Fe-1, can occasionally invade if Delta(r)G is between -45 and -90 kJ mol Fe-1, and can never invade if Delta(r)G is above -45 kJ mol Fe-1. The Delta(r)G threshold for invasion is sifted by the growth yield coefficient, the loss rate of cells, the maximum cell-specific Fe oxidation rate constant, and the temperature. The Delta(r)G threshold for invasion may be unable to rigorously predict the stable dominance of microbial metabolism, but can provide a rough indication for the possible microbial metabolism under current conditions., 2014, 31, 8, 645, 653, Scientific journal, 10.1080/01490451.2013.861703

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• Refereed, CHEMOSPHERE, PERGAMON-ELSEVIER SCIENCE LTD, The effect of zinc on aquatic microbial ecosystems and the degradation of dissolved organic matter, Mayumi Seto; Shigeki Wada; Satoru Suzuki, We developed a simple aquatic microbial ecosystem model in order to examine potential effects of zinc on microorganisms and the related degradation of dissolved organic matter (DOM). The model is a combination of both a traditional food chain and a microbial loop. The traditional food chain is mainly composed of phytoplankton and zooplankton, whilst the microbial loop is composed of DOM, bacteria and bacterivorous protozoa. We incorporated the suppressive effect of zinc on the bacterial uptake of DOM and assessed the steady state responses of the model for various zinc concentrations. The analytical and numerical results of the model implied that either zooplankton or bacterivorous protozoa might be the most vulnerable group to excessive zinc load than bacteria, depending on the grazing preference of zooplankton between phytoplankton and bacterivorous protozoa. The sensitivity analyses supported that the microbial loop solely is more sensitive to zinc than the coupled system combining both the traditional food chain and the microbial loop. (C) 2012 Elsevier Ltd. All rights reserved., Jan. 2013, 90, 3, 1091, 1102, Scientific journal, 10.1016/j.chemosphere.2012.09.014

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• Refereed, JOURNAL OF THEORETICAL BIOLOGY, ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, Regime shift and robustness of organism-created environments: A model for microbial ecosystems, Mayumi Seto; Yoh Iwasa, Organism-environment interactions are different from organism-resource interactions in two respects: (1) resources can only be consumed by organisms whereas environmental conditions can be increased or decreased depending on the species; (2) high resource conditions generally stimulate the growth of organisms, whereas extreme environmental conditions are not necessarily favored because each species usually has an optimum range for growth. To investigate the properties of an organism-environment feedback system, we analyze a model for microbial ecosystems in which a single microorganism species can modify the environmental pH. We demonstrate that the equilibrium level of the environmental pH can be partially regulated at a relatively constant value even if the pH in the influx to the ecosystem changes over a wide range. For species that acidify the medium, the equilibrium pH is somewhat lower than the pH optimal for the species. The pH-stabilizing effect of microorganisms is stronger if their growth is self-limited by the environmental pH. When the influx becomes sufficiently alkaline, the population of the organism suddenly disappears and the environmental pH changes abruptly. The system shows bi-stability and hysteresis and therefore differs from a standard resource competition model composed of a single species that consumes resources. (C) 2010 Elsevier Ltd. All rights reserved., Jan. 2011, 269, 1, 297, 306, Scientific journal, 10.1016/j.jtbi.2010.10.035

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• Refereed, CHEMOSPHERE, PERGAMON-ELSEVIER SCIENCE LTD, Mathematical explanation for the non-linear hydrophobicity-dependent bioconcentration processes of persistent organic pollutants in phytoplankton, Mayumi Seto; Itsuki C. Handoh, Phytoplankton play a vital role in determining the fate and transport of persistent organic pollutants (POPS) in aquatic ecosystems. Lipids in phytoplankton cells can accumulate POPS, and equilibrium partitioning of the chemicals between lipids and water can be deduced from the octanol/water partition coefficient (K(ow)). However, there is much uncertainty in the response of the bioconcentration factor (BCF) to K(ow). While distinct level-off and bell-shaped responses of BCF to Kow have been confirmed by laboratory experiments, a mathematical basis for the non-linear processes has been lacking. Using two differential equation models (Water-Phytoplankton and Water-Phytoplankton-Dissolved Organic Carbon) we here examine previously reported non-linearity between BCF and K(ow). Our modelling studies suggest that a level-off response of the true BCF (BCF estimated at equilibrium) to Kow could be attributed to the presence of dissolved organic carbon (DOC). The alternative bell-shaped response appears to be a consequence of the apparent BCF (BCF estimated at non-equilibrium) for which the slow uptake rate of chemical compounds of relatively large molecular mass by phytoplankton is responsible. (C) 2009 Elsevier Ltd. All rights reserved., Oct. 2009, 77, 5, 679, 686, Scientific journal, 10.1016/j.chemosphere.2009.07.048

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• Not Refereed, Interdisciplinary Studies on Environmental Chemistry Vol. 2 Environmental Research in Asia for Establishing a Scientist’s Network, Teasing out the non-linearity in the POPs-phytoplankton bioconcentration processes, Seto, M; Handoh, I.C, 2009, 11, 19
• Refereed, GEOCHEMICAL JOURNAL, GEOCHEMICAL SOC JAPAN, Chemical condition for the appearance of a negative Ce anomaly in stream waters and groundwaters, Mayumi Seto; Tasuku Akagi, Nine publications showing REE data in groundwaters and river water were examined to understand the general condition of terrestrial water where a negative Ce anomaly develops. It was found that the negative Ce anomaly only appeared when Fe, Mn and dissolved organic carbon (DOC) concentrations were low (Fe and Mn < 5 x 10(-5) mol/L and DOC < 10 mg/L). Assuming that Ce3+ and Fe2+ concentrations were limited by the formation of cerianite and ferrihydrite, respective redox potential (Eh) was calculated from each of Ce3+ and Fe2+ concentrations. For data sets displaying Ce anomalies, the calculated Ehs (cEhs) showed a 1:1 relationship between Ce and Fe. This relationship indicates that the absolute concentration of Ce in natural water may be thermodynamically determined in situ by Eh and pH when concentrations of Fe, Mn and DOC are poor., 2008, 42, 4, 371, 380, Scientific journal, 10.2343/geochemj.42.371

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• Refereed, JOURNAL OF THEORETICAL BIOLOGY, ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, Coexistence introducing regulation of environmental conditions, Mayumi Seto; Tasuku Akag, Interactions between environmental conditions and environment-affecting species have not been investigated extensively. In this study, the population dynamics of species yielding regulative feedback between temperature (a representative of environmental condition) and species with a temperature-altering trait was examined. We considered a simple closed model that described the population of two species (at least one of them had a temperature-altering trait) competing for one resource. The long-term outcomes of the competition and changes of temperature were explored against increasing background temperature. As a result of simulations, the regulation of temperature was accompanied by the coexistence of two species, which was contrary to the 'Gause's exclusion principle'. The steady-state analysis showed that (i) the temperature-altering trait allowed species to coexist and (ii) the coexistence of species with the trait could introduce the regulation of temperature. A 'trade-off' in their ability to utilize a resource plays a key role in this coexistence and homeostasis of temperature. This may imply that actual environmental conditions can be automatically stabilized by resource competition among species in natural ecosystems. (c) 2007 Elsevier Ltd. All rights reserved., Sep. 2007, 248, 2, 267, 274, Scientific journal, 10.1016/j.jtbi.2007.05.013

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• Refereed, JOURNAL OF THEORETICAL BIOLOGY, ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, Daisyworld inhabited with daisies incorporating a seed size/number trade-off: the mechanism of negative feedback on selection from a standpoint of the competition theory, M Seto; T Akagi, We reexamined a Daisyworld model from the traditional view of competition theory. Unlike the original model, white and black daisies in our model incorporate a seeding/germination trade-off against bare ground area without assuming the local temperature reward. As a result, the planetary temperature is automatically regulated by two species if the following conditions are met: (i) the species react equally to an environmental condition, but one can alter the environmental condition in the opposite direction to the other. (ii) that one of the two cannot have both a higher maximal growth rate and lower half-saturation constant (K) than those of the other. In other words, a pair of phenotypes incorporates a trade-off between quality and number of seeds. We found that the homeostatic regulation can also be reconciled with the adaptive evolution of optimal temperature. The results of simulation imply that biotic environmental feedback can also be maintained when the emergence of polymorphisms (black and white daisies) is closely linked to such a trade-off. (c) 2005 Elsevier Ltd. All rights reserved., May 2005, 234, 2, 167, 172, Scientific journal, 10.1016/j.jtbi.2004.11.029

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• Refereed, GEOCHEMICAL JOURNAL, GEOCHEMICAL SOC JAPAN, Influence of snow on iron release from soil, M Seto; T Akagi, The concentration of Fe in stream water and groundwater was measured monthly during a whole year. The study fields were Ozenuma lake and Senjougahara peatland, which snow covers for more than 5 months in winter. Iron concentration in water increased during snow-covered and thaw seasons with the synchronized decrease in Eh and pH for both stream water and groundwater. In snow-covered seasons, it is hypothesized that supply of melt water and/or coverage with ice layers during this period could cause the development of an anaerobic zone in underlying soil. This study suggests that change in the amount of snowfall or in the length of snow season may influence the geochemical cycle of iron., 2005, 39, 2, 173, 183, Scientific journal, 10.2343/geochemj.39.173

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• Not Refereed, CHEMISTRY & EDUCATION, The Chemical Society of Japan, Simple Method to Understand Redox Potential of Solution, SETO Mayumi; AKAGI Tasuku, 2003, 51, 12, 786, 787, 10.20665/kakyoshi.51.12_786

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• Refereed, Frontiers in Ecology and Evolution, Frontiers Media SA, How Thermodynamics Illuminates Population Interactions in Microbial Communities, Mayumi Seto; Yoh Iwasa, In traditional population models of microbial ecology, there are two central players: producers and consumers (including decomposers that depend on organic carbon). Producers support surface ecosystems by generating adenosine triphosphate (ATP) from sunlight, part of which is used to build new biomass from carbon dioxide. In contrast, the productivity of subsurface ecosystems with a limited supply of sunlight must rely on bacteria and archaea that are able generate ATP solely from chemical or electric energy to fix inorganic carbon. These “light-independent producers” are frequently not included in traditional food webs, even though they are ubiquitous in nature and interact with one another through the utilization of the by-products of others. In this review, we introduce theoretical approaches based on population dynamics that incorporate thermodynamics to highlight characteristic interactions in the microbial community of subsurface ecosystems, which may link community structures and ecosystem expansion under conditions of a limited supply of sunlight. In comparison with light-dependent producers, which compete with one another for light, the use of Gibbs free energy (chemical energy) can lead cooperative interactions among light-independent producers through the effects of the relative quantities of products and reactants on the available chemical energy, which is termed abundant resource premium. The development of a population theory that incorporates thermodynamics offers fundamental ecological insights into subsurface microbial ecosystems, which may be applied to fields of study such as environmental science/engineering, astrobiology, or the microbial ecosystems of the early earth., 30 Nov. 2020, 8, 10.3389/fevo.2020.602809

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• Refereed, Theoretical Ecology, Potential ecosystem regime shift resulting from elevated CO2 and inhibition of macroalgal recruitment by turf algae, Mayumi Seto; Ben P. Harvey; Shigeki Wada; Sylvain Agostini, Rising carbon dioxide (CO2) concentrations are predicted to cause an undesirable transition from macroalgae-dominant to turf algae-dominant ecosystems due to its effect on community structuring processes. As turf algae are more likely to proliferate due to the CO2 fertilization effect than macroalgae and often inhibit macroalgal recruitment, increased CO2 beyond certain levels may produce novel positive feedback loops that promote turf algae growth and thus can stabilize turf algae-dominant ecosystems. In this study, we built a simple competition model between macroalgae and turf algae in a homogeneous space to investigate the steady-state response of the ecosystem to changes in the partial pressure of CO2 (pCO2). We found that discontinuous regime shifts in response to pCO2 change can occur once turf algae coverage reaches a critical level capable of inhibiting macroalgal recruitment. The effect of localized turf algae density on the success rate of macroalgae recruitment was also investigated using a patch model that simulated a two-dimensional heterogeneous space. This suggested that in addition to the inhibitory effect by turf algae, a self-enhancing effect by macroalgae could also be important in predicting the potential discontinuous regime shifts in response to future pCO2 changes., Mar. 2023, 16, 1, 1, 12, Scientific journal, 10.1007/s12080-022-00550-0

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• Refereed, ARPHA Conference Abstracts, Microbial community ecosystem network model for chemical energy transport, Mayumi Seto; Michio Kondoh, 17 Oct. 2023, International conference proceedings, 10.3897/aca.6.e108960

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• Refereed, Ecology Letters, Microbial redox cycling enhances ecosystem thermodynamic efficiency and productivity, Mayumi Seto; Michio Kondoh, Microbial life in low-energy ecosystems relies on individual energy conservation, optimizing energy use in response to interspecific competition and mutualistic interspecific syntrophy. Our study proposes a novel community-level strategy for increasing energy use efficiency. By utilizing an oxidation–reduction (redox) reaction network model that represents microbial redox metabolic interactions, we investigated multiple species-level competition and cooperation within the network. Our results suggest that microbial functional diversity allows for metabolic handoffs, which in turn leads to increased energy use efficiency. Furthermore, the mutualistic division of labour and the resulting complexity of redox pathways actively drive material cycling, further promoting energy exploitation. Our findings reveal the potential of self-organized ecological interactions to develop efficient energy utilization strategies, with important implications for microbial ecosystem functioning and the co-evolution of life and Earth., Oct. 2023, 26, 10, 1714, 1725, Scientific journal, 10.1111/ele.14287

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• Refereed, Frontiers in Marine Science, Cohesive bond strength of marine aggregates and its role in fragmentation, Yasuhito Hayashi; Shigeki Wada; Mayumi Seto; Yasuhisa Adachi, Marine aggregates are one of the main contributors to carbon sequestration in the deep sea through the gravitational settling of biogenic particles formed from the photosynthetic products of phytoplankton. The formation of large particles due to aggregation processes has been the focus of studies in the past, but recent findings on the spatio-temporal distribution of particles suggests that the fragmentation of aggregates plays an important role in aggregate dynamics. Here, we assessed the yield strength of aggregates derived from natural planktonic communities in order to analyze the cohesive bond strength and further understand fragmentation. The experimental approach was designed around the use of a Couette device, which produces a constant laminar shear flow of water. Aggregates were found to have a higher yield strength (~289 ± 64 nN) during phases of nutrient depletion than those of mineral particles such as montmorillonite. Based on an estimated cohesive bond strength of 96 nN a numerical model to predict the temporal variation of aggregate size was created. The output of this model indicates that cohesive bond strength is a major determinant of the size of aggregates in motion. Our findings suggest that the dynamics of marine aggregates are greatly influenced by cohesive bond strength and the role in fragmentation., 2023, 10, Scientific journal, 10.3389/fmars.2023.1167169

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• Refereed, JOURNAL OF THEORETICAL BIOLOGY, ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, Individual and combined suppressive effects of submerged and floating-leaved macrophytes on algal blooms, Mayumi Seto; Noriko Takamura; Yoh Iwasa, Shallow lakes and ponds are often characterised either by clear water with abundant submerged macrophytes or by turbid water with abundant phytoplankton. Blooms of toxic filamentous blue-green algae (cyanobacteria) often dominate the phytoplankton community in eutrophic lakes, which threatens ecological functions and biodiversity of freshwater ecosystems. We studied a simple lake model in order to evaluate individual and combined suppressive effects of rooted submerged and rooted floating-leaved macrophytes on algal blooms. Floating-leaved plants are superior competitors for light, whereas submerged plants absorb and reduce available phosphorus in a water column that rooted floating-leaved plants exploit to a lesser extent. We found that mixed vegetation that includes both submerged and floating-leaved plants is more resistant than vegetation comprised by a single plant type to algal invasion triggered by phosphorus loading. In addition, competitive exclusion of submerged plants by floating-leaved plants may promote an algal bloom. These predictions were confirmed by the decision tree analysis of field data from 35 irrigation ponds in Hyogo Prefecture, Japan. (C) 2012 Elsevier Ltd. All rights reserved., Feb. 2013, 319, 122, 133, Scientific journal, 10.1016/j.jtbi.2012.11.016

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MISC

• Not Refereed, 地球化学, 「生物地球化学」特集に寄せて, 瀨戸 繭美; 瀬戸 繭美; 板井 啓明, 2017, 51, 4, 157, 158, 10.14934/chikyukagaku.51.157

  DOI URL
• Not Refereed, Abstracts of Annual Meeting of the Geochemical Society of Japan, GEOCHEMICAL SOCIETY OF JAPAN, The effect of zinc on marine microbial food web and biodegradation of dissolved organic matter, Seto Mayumi; Wada Shigeki, 亜鉛は生物の必須元素である一方で過剰摂取によって毒性を発現することが知られている。現在水生生物の個体群レベルでの保全に留意した亜鉛の環境基準として、海水域では生物A類型で0.02mg L-1、 生物特A類型で0.01mg L-1が設定されているが、沿岸域ではこれを上回る亜鉛濃度がしばしば観測されており、水圏生態系の環境リスクが懸念されている。更に近年、亜鉛の添加によって海水中のバクテリアによる溶存有機炭素(DOM)の利用が阻害され、DOMの分解速度が低下することが室内実験によって明らかにされた。これは海水への亜鉛の負荷が海洋微生物食物網と海水中のDOM動態の両方に影響を及ぼしうることを示唆する。 本研究では、 (1)DOM・バクテリア・ナノ繊毛虫から成る微生物ループ、並びに(2) (1)に植物プランクトン・動物プランクトンを加えた微生物食物網の2つのモデルを構築し、亜鉛の負荷が海洋の微生物生態系並びにDOM分解に及ぼす影響をモデルの数理解析とシミュレーションを通して検証した(図1)。本モデルでは対象空間を均一な系であると仮定し、連立常微分方程式によって微生物間の相互作用やDOMフローのプロセスについて記述した。(1), (2)の2つのモデルの時間動態並びに定常状態を解析・数値計算し、亜鉛の負荷量に対する海水中の全炭素量、DOM量、各生物の炭素量の割合の応答について調べた。 亜鉛による微生物ループへの影響を検証した結果、亜鉛の負荷量が大きくなるにつれてバクテリアの捕食者であるナノ鞭毛虫の減少が予測された。また、その減少率はDOMの少ない貧栄養の環境下において高くなる傾向が示された。亜鉛濃度がある閾値を上回った場合には、ナノ繊毛虫が存続を維持することができなくなり、微生物ループが崩壊する可能性が示唆された。植物プランクトン・動物プランクトンを加えた微生物食物網の場合、植物プランクトンの生産量が高くDOC供給が多い場合には亜鉛によるナノ鞭毛虫の減少を緩和する傾向が示されたが、一方で動物プランクトンによるナノ繊毛虫への捕食圧が高い場合には再びナノ繊毛虫の存続が維持できなくなることが予測された。また、ナノ繊毛虫が減少するにつれて海水中の全炭素量に占めるDOMの割合が上昇することが予測された。, 2011, 58, 0, 275, 275, 10.14862/geochemproc.58.0.275.0

  DOI URL
• Not Refereed, GEOCHIMICA ET COSMOCHIMICA ACTA, PERGAMON-ELSEVIER SCIENCE LTD, Seasonal change in Eh-pH condition of natural water and consistency between Fe and Ce concentrations, M Seto; T Akagi, Sep. 2003, 67, 18, A423, A423, Summary international conference
• Not Refereed, 教育システム研究, 高等学校生物教育における直接体験型生態学教育の重要性, 矢野幸洋; 瀬戸 繭美, 2018, 14, 99, 102
• Not Refereed, 化学と工業, 積雪が形成する還元的環境における土壌有機物の分解挙動, 瀬戸 繭美; 赤木 右, 2003, 56, 7, 817
• 日本地球化学会年会講演要旨集, 植物プランクトンにおける残留性有機汚染物質の濃縮過程の数理モデル, 瀬戸繭美; 半藤逸樹, 2010, 57th
• Research Square Platform LLC, Microbial redox interplay enhances biodiversity and ecosystem productivity, Mayumi Seto; Michio Kondoh, Abstract A significant portion of the Earth’s biodiversity and biomass is from the subsurface biosphere, where chemotrophic microbial species harness diverse inorganic oxidation-reduction reactions (redox reactions) as a major source of metabolic energy while driving biogeochemical cycles. Given the limited availability of energy in the anaerobic environment, a fundamental question concerns what interplay between the chemical environment and chemotrophic community enables the persistence of whole biogeochemical systems. Here, using a thermodynamics-based mechanistic model that maps the interplay between diverse chemotrophic species and chemical compounds onto a redox network, we show that cycles of redox reactions mediate chemotrophic interactions in a way that increases the complexity of both redox reaction networks and microbial communities and enhances the community-level efficiency of energy metabolism. The high efficiency and complexity of biogeochemical systems arises from the self-organised ecological niche segmentation of microbes. More specifically, a consortium of chemotrophic species that subdivide a long-reaction pathway into shorter-reaction segments enhance each other’s population growth, replaces the species that monopolises the long-reaction pathway, and increases ecosystem productivity. An ecologically driven ‘division of metabolic labour’ in the chemotrophic community provides a novel mechanism through which an intimate life-environment interplay concurrently enhances biodiversity and ecosystem productivity., 19 Oct. 2021, 10.21203/rs.3.rs-959776/v1

  PermalinkURLDOI URL

Books etc

• 遺伝子・多様性・循環の科学 : 生態学の領域融合へ, 京都大学学術出版会, 門脇, 浩明; 立木, 佑弥, 呼吸の多様性が駆動する元素循環, Feb. 2019, v, 432p, 図版 [8] p, 9784814001903

  CiNii Books URL

Presentations

• Poster presentation, 16 Mar. 2024, 21 Mar. 2024
• Oral presentation, 16 Mar. 2024, 21 Mar. 2024
• Poster presentation
• Oral presentation, 17 Mar. 2023, 21 Mar. 2023
• Nominated symposium
• Nominated symposium, 09 Mar. 2023, 10 Mar. 2023
• Nominated symposium, 06 Mar. 2023, 08 Mar. 2023
• Nominated symposium
• Public discourse
• Oral presentation, 07 Sep. 2022, 09 Sep. 2022
• Oral presentation, 05 Sep. 2022, 07 Sep. 2022
• Oral presentation, 14 Mar. 2022, 19 Mar. 2022
• 瀬戸 繭美, 日本生態学会第66回全国大会, 化学合成の代謝エネルギー獲得量に律速された微生物個体群動態についての新しい洞察, Oral presentation, Mar. 2019, False
• SETO Mayumi, 24th International Symposium on Environmental Biogeochemistry, Potsdam, Germany, Catabolic mutualistic interactions can lead ecosystem expansion, Poster presentation, 20 Sep. 2019, 22 Sep. 2019, 27 Sep. 2019, True

  共同研究・競争的資金等URL
• 瀬戸繭美, 第16回生物数学の理論とその応用〜生命現象の定量的理解に向けて〜, 微生物代謝ネットワークと生態系の共進化 : 化学エネルギー観点からの進化的制約とは?, Nominated symposium, 28 Jan. 2020
• 瀬戸繭美, 生態研セミナー, エネルギーで読み解く 微生物相互作用と微生物代謝の進化, Oral presentation, 21 Feb. 2020
• 瀬戸 繭美, 第29回日本数理生物学会, エネルギー獲得を巡る微生物相互作用: ニッチ構築と物質フローの拡大, Oral presentation, Sep. 2019, False
• 瀬戸繭美, ソフトマターの未来材料シンポジウム, 酸化還元反応と生命 - 微生物代謝の進化と生態系の発展 -, Nominated symposium, 10 Jan. 2020
• SETO Mayumi, Ecohydrology Research Symposium, Waterloo, Canada, Application of bioenergetics in Astrobiology and Ecology, Nominated symposium, Dec. 2019, True
• Mayumi Seto, ELSI Seminar, Microbial growth, interactions, and evolution at the energetic edge : Theoretical perspectives based on thermodynamics and population dynamics, Public discourse, 18 Feb. 2020
• Mayumi Seto, The 31st Annual Meeting of Japanese Society for Mathematical Biology (JSMB2021), Competition and cooperation in microbial nitrification metabolism, Oral presentation, 15 Sep. 2021, 13 Sep. 2021, 15 Sep. 2021

  共同研究・競争的資金等URL
• Mayumi Seto, 京都大学生態学研究センター共同利用ワークショップ 微生物を軸とした群集構造研究の統合とさらなる展開, Exploring microbial community from the perspective of metabolic energy, Nominated symposium, 24 Sep. 2021

  共同研究・競争的資金等URL
• Mayumi Seto, iTHEMS Biology Seminar, Application of bioenergetics to microbial modeling, Public discourse, 29 Jul. 2021

  共同研究・競争的資金等URL
• 瀬戸繭美, ダーウィンセミナー, 化学合成微生物群集における代謝の協力, Oral presentation, 17 May 2021

  共同研究・競争的資金等URL
• 瀬戸繭美, 第69回日本生態学会, 化学合成微生物群集と酸化還元ネットワークの共発展, Oral presentation, 15 Mar. 2022, 14 Mar. 2022, 19 Mar. 2022

  共同研究・競争的資金等URL
• 瀬戸繭美, 日本生態学会第68回全国大会, Mutualistic interspecific interactions through energy production reactions, Oral presentation, 19 Mar. 2021, 17 Mar. 2021, 21 Mar. 2021

  共同研究・競争的資金等URL
• 瀬戸繭美, 2020年度日本数理生物学会年会, 光非依存生産者の種間相互作用と生物地球化学サイクルの数理モデル, 22 Sep. 2020

  共同研究・競争的資金等URL
• 瀬戸繭美, 2020年度日本数理生物学会年会, 高校生ワークショップ「高校生のための数理生物学」/生物増殖のモデリング・シミュレーションを体験してみよう, 21 Sep. 2020
• 瀬戸繭美, 2020年度日本数理生物学会年会, 高校生ワークショップ「高校生のための数理生物学」/「微生物 + エネルギー」を「理科 + 数理モデル」で理解する, 21 Sep. 2020
• 環境科学国際ワークショップ, Assessment of instructions on protection against food contaminated with radiocesium in Japan in 2011, 2018
• The Society for Risk Analysis, Asia Conference 2018, Assessment of instructions on protection against food contaminated with radiocesium in Japan in 2011, 2018
• 日本生態学会第65回全国大会, 呼吸反応に着目した微生物群集の多様性と生態系機能の関係, 2018
• 環境科学国際ワークショップ, Assessment of instructions on protection against food contaminated with radiocesium in Japan in 2011, 2018
• The Society for Risk Analysis, Asia Conference 2018, Assessment of instructions on protection against food contaminated with radiocesium in Japan in 2011, 2018
• 2017年度 数学・物理学・情報科学シンポジウム, 微生物呼吸が駆動する元素循環: 呼吸を介して読み解く栄養共生と物質フロー, 2017
• 第5回JAMBIOフォーラム, 個体群動態モデルを用いた環境変動に対する生物応答の予測, 2016
• 日本生態学会第６２回全国大会, 化学合成細菌の群集間相互作用と共存のメカニズム, 2015
• 2015 AGC-CGU Joint Assembly, Metabolic energy-based habitability of methanotrophic life on Mars, 2015
• 2015 Joint Meeting of JSMB and CJK Colloquium on Mathematical Biology, Chemotrophic bacteria and material cycles: How they increase fluxes?, 2015
• 進化群集生態学シンポジウム2015, 生物は本当に物質流を増やすのか？: 化学合成細菌群集を例として, 2015
• 2015 AGC-CGU Joint Assembly, Metabolic energy-based habitability of methanotrophic life on Mars, 2015
• 2015 Joint Meeting of JSMB and CJK Colloquium on Mathematical Biology, Chemotrophic bacteria and material cycles: How they increase fluxes?, 2015
• JSMB/SMB 2014 Osaka, Invasibility of chemotrophic microorganisms, 2014
• JSMB/SMB 2014 Osaka, The effect of foraging of honeybees on distributions of two competing annual flowers, 2014
• The symposium on recent developments in evolutionary community ecology, Chemotrophic bacterial roles in biogeochemical material cycles, 2014
• 日本地球化学会年会2014年度, ボックスモデル計算による化学合成細菌群集の地球化学的ニッチの検証, 2014
• The 2014 ISEB short course, Ecological and evolutionary perspectives of syntrophic communities, 2014
• JSMB/SMB 2014 Osaka, Invasibility of chemotrophic microorganisms, 2014
• JSMB/SMB 2014 Osaka, The effect of foraging of honeybees on distributions of two competing annual flowers, 2014
• The symposium on recent developments in evolutionary community ecology, Chemotrophic bacterial roles in biogeochemical material cycles, 2014
• The 2014 ISEB short course, Ecological and evolutionary perspectives of syntrophic communities, 2014
• One Health Summit 2012, The validity of safety measures for food contaminated with radioactive materials, 2012
• China-Japan-Korea International Conference on Mathematical Biology, Possible effects of ocean acidification on a phytoplankton-pH feedback, 2012
• 2012 International Mathematica Symposium, Probabilistic risk assessment for food contamination, 2012
• 日本地球化学会2012年会, 生物は環境の「ノイズ」でしかないのか？ー地球化学的問題に対する数理生物学的アプローチ, 2012
• 日本地球化学若手シンポジウム2012, 数理モデルで探る微生物生態系の法則性, 2012
• Third International Symposium on the Ocean in a High CO2 world, Potential biological pH buffering effect and regime shift, 2012
• International Society for Environmental Biogeochemistry Short Course, Mathematical model for the dynamics of chemolithotrophic bacteria, 2012
• One Health Summit 2012, The validity of safety measures for food contaminated with radioactive materials, 2012
• China-Japan-Korea International Conference on Mathematical Biology, Possible effects of ocean acidification on a phytoplankton-pH feedback, 2012
• 2012 International Mathematica Symposium, Probabilistic risk assessment for food contamination, 2012
• Third International Symposium on the Ocean in a High CO2 world, Potential biological pH buffering effect and regime shift, 2012
• International Society for Environmental Biogeochemistry Short Course, Mathematical model for the dynamics of chemolithotrophic bacteria, 2012
• 日本生態学会第58回全国大会, 水圏で閾値な話：数理モデルによる生態学的閾値の導出, 2011
• 第34回生命数理セミナー, 食品に対する放射性物質検査と出荷制限解除条件の妥当性, 2011
• 第21回数理生物学会大会, 食品に対する放射性物質検査と出荷制限解除条件の妥当性, 2011
• 地球化学会年会2011, 亜鉛負荷による海洋微生物食物網並びに溶存有機炭素分解に対する影響予測, 2011
• 下田臨海研究センター合同セミナー, 亜鉛負荷による海洋微生物食物網並びに溶存有機炭素分解に対する影響予測, 2011
• JSMB Annual Meeting 2011, The validity of safety measures for food contaminated with radioactive materials, 2011
• Annual Meeting of GSJ 2011, The effect of zinc on aquatic microbial ecosystems and the degradation of dissolved organic matter, 2011
• The effect of zinc on aquatic microbial ecosystems and the degradation of dissolved organic matter, 2011
• 日本生態学会第57回全国大会, ため池管理のための数理モデル: 水生植物がアオコの発生に及ぼす影響, 2010
• 2010年度日本地球化学会年会, 植物プランクトンにおける残留性有機汚染物質の濃縮過程の数理モデル, 2010
• 第20回日本数理生物学会札幌大会, 被食-捕食者系における微生物-pH相互作用 Microorganism-pH interactions in a prey-predator system, 2010
• 第２回水環境セミナー, 数理モデルを用いた水圏生態系における生態学的閾値の導出 -アオコ発生と微生物ループ崩壊の予防を目標として-, 2010
• Advanced Course and Conference on the Mathematical Biology: Modelling and Differential Equations, Teasing out the non-linearity in the POPs-phytoplankton bioconcentration processes, 2009
• 第19回日本数理生物学会, Non-linearities in bioconcentration of persistent organic pollutants in phytoplankton, 2009
• 第36回生態リスクCOE公開講演会, 淡水生態系における生物の環境構築による生態系の安定化とレジームシフト, 2009
• Advanced Course and Conference on the Mathematical Biology: Modelling and Differential Equations, Teasing out the non-linearity in the POPs-phytoplankton bioconcentration processes, 2009
• 第55回日本生態学会, A mathematical model for biotic regulation of physicochemical conditions, 2008
• 第18回日本数理生物学会, Does a life-environment feedback increase the probability of coexistence?, 2008
• 第18回日本数理生物学会, The effect of biological activity on environmental stability, 2008
• Interdisciplinary Symposium on Environmental Sciences: To Establish an Asian Network of Environmental Researchers, Puzzling out the non-linearity in the POPs-phytoplankton bioconcentration processes, 2008
• Interdisciplinary Symposium on Environmental Sciences: To Establish an Asian Network of Environmental Researchers, Puzzling out the non-linearity in the POPs-phytoplankton bioconcentration processes, 2008
• 日本地球惑星科学連合2007年大会, 陸域窒素サイクルにおける草食動物の役割, 2007
• Joint Annual Meetings of The Society for Mathematical Biology and The Japanese Society for Mathematical Biology - 2007, Coexistence introducing regulation of environmental conditions, 2007
• 日本地球惑星科学連合2007年大会, 地下水と渓流水におけるCe anomalyの出現に関する考察, 2007
• ECEM’07 The 6th European Conference on Ecological Modelling, The enhancement of nitrification in the presence of herbivores, 2007
• Joint Annual Meetings of The Society for Mathematical Biology and The Japanese Society for Mathematical Biology - 2007, Coexistence introducing regulation of environmental conditions, 2007
• ECEM’07 The 6th European Conference on Ecological Modelling, The enhancement of nitrification in the presence of herbivores, 2007
• International Workshop on Ecological Informatics of Chaos and Complex Systems, The mechanism of negative feedback on selection for environment-altering species from a standpoint of the competition theory, 2006
• 日本地球惑星科学連合2006年大会, 栄養塩獲得競争から生じる環境-生物-栄養塩間自己調節フィードバック, 2006
• Japanese-Korean Joint Meeting for Mathematical Biology, Stabilization of environmental conditions introduced by environmental- altering traits of competing species, 2006
• International Workshop on Ecological Informatics of Chaos and Complex Systems, The mechanism of negative feedback on selection for environment-altering species from a standpoint of the competition theory, 2006
• Japanese-Korean Joint Meeting for Mathematical Biology, Stabilization of environmental conditions introduced by environmental- altering traits of competing species, 2006
• 地球惑星科学関連学会2005年合同大会, 種まき競争デイジーワールドモデル, 2005
• 第7回日本進化学会, 資源獲得競争から生じる生物-環境間フィードバック調節モデル(種まき競争デイジーワールドモデル), 2005
• 日本数理生物学会第15回大会, 資源獲得競争から生じる生物-環境間フィードバック調節モデル, 2005
• 2005年度日本地球化学会第52回年会, 資源獲得競争を巡る種間競走から生じる環境調節フィードバックモデル, 2005
• 地球惑星科学関連学会2003年合同大会, 地球表層における鉄循環への雪による影響, 2003
• Goldschmidt Conference, Seasonal change in Eh & pH condition of natural water and consistency between Fe and Ce concentrations, 2003
• Goldschmidt Conference, Seasonal change in Eh & pH condition of natural water and consistency between Fe and Ce concentrations, 2003
• 日本陸水学会第67回大会, 融雪期における表面水および地下水の酸化還元電位, pHの変化, 2002
• 瀬戸繭美, 第70回 日本生態学会大会, 微生物レドックスネットワークの トポロジーに依存した熱力学的効率, 17 Mar. 2023, 17 Mar. 2023, 21 Mar. 2023

  共同研究・競争的資金等URL
• Mayumi Seto, Research meeting: Principle of Microbial Ecosystems, Thermodynamics-based microbial network modeling: Efficient energy-use strategy at community level, 14 Mar. 2023

  共同研究・競争的資金等URL
• 瀬戸繭美, 触媒・酵素・エコシステムの統合理解に向けた数理実験融合, 微生物反応ネットワークと理論研究の展望, 09 Mar. 2023, 09 Mar. 2023, 10 Mar. 2023

  共同研究・競争的資金等URL
• Mayumi Seto, 11th ELSI symposium: The Living Universe, Eco-redox network model: Efficient energy-use strategy at microbial community level, 08 Mar. 2023, 06 Mar. 2023, 08 Mar. 2023

  共同研究・競争的資金等URL
• 瀬戸繭美, 数理生物学のフロンティア2022, 化学合成微生物群集の熱力学的理解: 群集レベルのエネルギー利用最適化戦略, 13 Dec. 2022
• Mayumi Seto, RIKEN seminar, Eco-redox model: Towards a fundamental understanding of ecological metabolism, 06 Dec. 2022

  共同研究・競争的資金等URL
• 瀬戸繭美, 2022年 日本数理生物学会年会, Q*則: 生命とギブスエネルギーのフィードバック, 05 Sep. 2022, 05 Sep. 2022, 07 Sep. 2022

  共同研究・競争的資金等URL
• 瀬戸繭美, 2022年度日本地球化学会年会, Eco-redox network model を用いた化学合成微生物群集 の発展とエネルギー転換効率に関する熱力学的考察, 07 Sep. 2022, 07 Sep. 2022, 09 Sep. 2022

  共同研究・競争的資金等URL
• 瀬戸繭美, 理論生物学スプリングスクール2024, 第一原理計算に立脚した微生物群集ダイナミクスの理解, Public discourse, 20 Feb. 2024

  共同研究・競争的資金等URL
• 瀬戸繭美, 東京工業大学地球生命研究所一般講演会2024, How does life connect cell and Earth energy?, Invited oral presentation, 01 Feb. 2024

  共同研究・競争的資金等URL
• Mayumi Seto, "Major Microbial Transitions: From the origin of life to the origin of the domains"in The 36th JSME& The 13th ASME, Adaptive Metabolic Evolution: Converging on Ecological Redox Niches, Invited oral presentation, 28 Nov. 2023, 28 Nov. 2023, 30 Nov. 2023

  共同研究・競争的資金等URL
• Mayumi Seto, Research Workshop on Microbial Ecological Theory: "Selfishness? interdependency? in Microbial Ecosystems", Unveiling cooperative division of labor: Exploring thermodynamic considerations and network configurations, Nominated symposium, 27 Nov. 2023

  共同研究・競争的資金等URL
• Mayumi Seto, The 2nd Joint Symposium of the international Societies for Environmental Biogeochemistry and Subsurface Microbiology, Microbial community ecosystem network model for chemical energy transport, Oral presentation, 23 Oct. 2023, 22 Oct. 2023, 28 Oct. 2023

  共同研究・競争的資金等URL
• Mayumi Seto, University of Nebraska-Lincoln with Pacific Northwest National Laboratory (PNNL)'s River Corridor SFA, Microbial ecology's impact on redox network architecture, Public discourse, 18 Oct. 2023

  共同研究・競争的資金等URL
• 瀬戸繭美, 日本地球化学会第70回年会, 微生物による酸化還元反応の選択性における速度論と熱力学の寄与, 21 Sep. 2023, 21 Sep. 2023, 23 Sep. 2023

  共同研究・競争的資金等URL
• 瀬戸繭美, 2023年度数理生物学会年会, 微生物の酸化還元ネットワーク理解のための数理「化学」アプローチ, Invited oral presentation, 06 Sep. 2023, 04 Sep. 2023, 06 Sep. 2023

  共同研究・競争的資金等URL
• Mayumi Seto, Feasible but Undiscovered Metabolisms Ⅱ: Thermodynamics, Evolution, and the Origin of life, Feasible microbial redox network at a community scale, Nominated symposium, 24 Aug. 2023, 23 Aug. 2023, 25 Aug. 2023

  共同研究・競争的資金等URL
• Mayumi Seto, The 8th CIJK International Conference on Mathematical and Theoretical Biology, An integrated theoretical approach towards ecological understanding of microbial communities and reaction networks, Nominated symposium, 29 Jun. 2023, 27 Jun. 2023, 01 Jul. 2023

  共同研究・競争的資金等URL
• 瀬戸繭美, 第37回数学カフェ, 生態系・多様性の数理生物学 生態系は巨大な電気回路？電子で繋がる微生物ネットワークとそのエネルギー利用戦略, Public discourse, 14 May 2023

  共同研究・競争的資金等URL

Research Projects

• Grant-in-Aid for Transformative Research Areas (A), 01 Apr. 2023, 31 Mar. 2025, 23H04652, Exploration of theoretical planetary ecology in the CO world., 瀬戸 繭美, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Nara Women's University, 6500000, 5000000, 1500000, kaken;rm:published_papers;rm:published_papers;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations

  対象リソースIRI
• Apr. 2023, Mar. 2024, Principal investigator, 太陽光動力ビオトープの設置とカーボンニュートラル・生態学の教育・研究への活用, 遊佐陽一; 篠原隆一郎; 吉田和弘; 片野泉, 公益財団法人岩谷直治記念財団, 第49回 (2022年度) 岩谷科学技術研究助成
• Apr. 2022, Mar. 2025, 22K06390, Principal investigator
• 基盤研究(B), 01 Apr. 2019, 31 Mar. 2023, 19H04234, 海洋酸性化に対する海藻藻場生態系のエネルギーフローの応答, 和田 茂樹; 瀬戸 繭美; AGOSTINI SYLVAIN; 今 孝悦; 佐藤 雄飛; BENJAMIN HARVEY; 大森 裕子, 日本学術振興会, 科学研究費助成事業 基盤研究(B), 筑波大学, 17290000, 13300000, 3990000, 本プロジェクトでは式根島CO2シープを利用し、光合成・生食連鎖・腐食連鎖のそれぞれの過程を解析した。 光合成：海中に付着基板を設置して自然の付着藻類群集を得た上でその光合成速度を測定したところ、藻類群集の光合成速度は海洋酸性化の進行に伴い増大した。一方で、藻類バイオマスには大きな変化が認められない。光合成とバイオマスの不一致には、高CO2海域で優占する単細胞の藻類が関与している。通常海域は仮根で強く付着する大型藻類が優占するが、高CO2海域は粘液で緩く付着する単細胞藻類が優占するため、藻体バイオマスが容易に脱離し、エネルギーが藻場外に輸送される。 生食連鎖と腐食連鎖：藻類の葉上に生息する動物と脱離して海底を漂流する藻体上の動物群集を解析した。その結果、量的パラメーター(総個体数)に関しては、全ての試料においてCO2濃度の違いに対応する有意な差は認められなかった。葉上の動物の種数は高CO2環境下で有意に減少したが、脱離した藻体上の動物相の種数に有意な変化は認められない。すなわち、生食連鎖の起点となる葉上の動物群集においてのみ、生物多様性が低下する。さらに、PERMANOVAを用いて群集組成を比較したところ、春～夏(高バイオマス季)・秋～冬(低バイオマス季)の両シーズンでCO2濃度に対する群集組成の有意な変化が認められたが、脱離藻体上においては春～夏シーズンのみで有意な変化が認められた。これらの結果は、海洋酸性化が生食連鎖と腐食連鎖に異なる影響を及ぼすことを意味する。しかし、量的パラメーターに影響が見られないことは、高次栄養段階のエネルギーフローへの影響は限定的であることを示唆している。 さらに、生態系の変化を説明するため、数理モデルを構築した解析を行った。海藻、微細藻、サンゴの3つのプレーヤーからなる生態系モデルにより、生物群間の競争関係が生態系のレジームシフトを引き起こすことが示された。, Competitive research funding, kaken;rm:published_papers

  対象リソースIRI
• Grant-in-Aid for Scientific Research (C), 01 Apr. 2019, 31 Mar. 2022, 19K06853, Principal investigator, Theoretical understanding of the population dynamics and evolution of chemotrophs under the limitation of metabolic energy acquisition per redox reaction., Seto Mayumi, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Nara Women's University, 2340000, 1800000, 540000, The fundamental ecological theories have been developed based on observations of the Earth's surface ecosystems (e.g., terrestrial and coastal ecosystems). meanwhile, the deep subsurface environments also harbor enormous biomass, in which bacteria and archaea support primary production. The amount of energy available in the deep sea is far less than that available in surface ecosystems. In this study, we conducted a theoretical study using a population dynamics model to understand microbial communities and ecosystems that are independent of light as an energy source. The results revealed that microorganisms increase not only the reaction rate but also the energy conversion efficiency by passing metabolites to other microorganisms., Competitive research funding, kaken;rm:published_papers;rm:published_papers;rm:published_papers;rm:published_papers;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations

  対象リソースIRI
• Apr. 2020, Mar. 2021, Principal investigator, 環境トークバトルゲーム「がちかん」を用いた対話型環境教育・コミュニケーションプログラムの開発と実践, 瀬戸 繭美, 公益財団法人 科学技術融合振興財団, 公益財団法人 科学技術融合振興財団 平成30年度（2018年度） 調査研究助成, 0, 0, 0, Competitive research funding, rm:social_contribution;rm:social_contribution

  対象リソースIRI
• Apr. 2019, Mar. 2020, Principal investigator, 環境教育ディベートゲーム「がちかん」を用いた環境コミュニケーションの実践, 瀬戸 繭美, 公益財団法人日本環境教育機構, 公益財団法人 日本環境教育機構 平成 30 年度助成金, 0, 0, 0, Competitive research funding, rm:social_contribution

  対象リソースIRI
• Grant-in-Aid for Young Scientists (B), 2011, 2013, 23770024, Theoretical explanations for the microbial effects on physicochemical environmental conditions from the stand point of Ecology, Geochemistry, and Evolution., SETO Mayumi, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Nara Women's University, 4550000, 3500000, 1050000, The objective of this study was to theoretically explore the biological effects on physicochemical environmental conditions from the stand point of ecology, evolution, and geochemistry. Mathematical models describing microbial ecosystems were analytically and numerically examined to compare the behavior of the models with and without microbial effects on environmental conditions (pH, concentrations of nutrients and heavy metals, and Gibbs free energy etc.) . The results indicated that microbial effects on environmental conditions affect ecosystem stability and population extinction risk. Furthermore, microbial activities may control fluxes and speciation of redox species, and consequently the Gibbs energy of ecosystems., kaken_url;kaken

  対象リソースIRI
• 特別研究員奨励費, 2006, 2007, 06J01285, 環境状態-生物選択-資源の3要素の相互作用から生じる自己調節フィードバックモデル, 瀬戸 繭美, 日本学術振興会, 科学研究費助成事業 特別研究員奨励費, 九州大学, 1900000, 1900000, 本年度の研究概要 本研究では、生態系に生物が存在することによって環境状態の変動が外的撹乱から予測されるよりも小さくなることに着目し、その機序を解き明かすことを目的として数理モデルを用いた解析を行ってきた。生態学の分野において生物が物理化学的環境状態に寄与することでその状態に安定性をもたらしうることに着目したモデル研究はほとんどない。申請者は申請当初、モデル研究の拡張に際して、生物や資源の数を増やすことや生物のパラメタに進化を導入することを考えていたが、系の本質的な理解のために数学的解析が重要であることを認識し、まず2種1資源1環境系の解析を試みた。 その結果、生物が環境に影響を及ぼすことで安定な共存点が現れ、共存が生じることで環境(気温やpH)が外部の撹乱に全く依存せず一定に制御されることが数学的に示された。この結果は2007年にJournal of Theoretical Biologyに掲載された。その後、微生物培養槽モデル(ケモスタットモデル)においてシアノバクテリアとpHが相互作用関係にある系を数理モデルで検証した結果、いくつかの条件が満たされれば1種の微生物でさえもpHの安定制御効果をもたらしうることが示された(これは現在投稿準備中である)。またこの研究からは環境制御効果は外的撹乱が大きくなりすぎると一気に失われてしまい、生態系の崩壊を招く危険性をはらんでいることがわかった。人間活動による外的な環境撹乱(e.x.温暖化、酸性降下物の上昇)が大きくなる昨今、生物がどのようにこれに応答し制御しうるかを知ることは非常に重要な課題であると考えられる。, kaken

  対象リソースIRI
• Grant-in-Aid for Scientific Research (C), 01 Apr. 2022, 31 Mar. 2025, 22K06390, Toward an integrated theory of the relationship between chemotrophic microbial communities and free energy, 瀬戸 繭美, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Nara Women's University, 4160000, 3200000, 960000, kaken;rm:published_papers;rm:published_papers;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations;rm:presentations

  対象リソースIRI

Ⅲ．社会連携活動実績

１．公的団体の委員等（審議会、国家試験委員、他大学評価委員，科研費審査委員等）

• Sep. 2022, Dec. 2022
• Apr. 2016, 9999
• Apr. 2020, Mar. 2022, Society
• Apr. 2018, Mar. 2021, Society
• Apr. 2018, Mar. 2021, Autonomy
• Sep. 2021, Aug. 2023, Society
• Apr. 2021, 9999, Society
• Apr. 2022, 9999, Autonomy
• Jan. 2023, 9999, Society