Using Maximum Entropy Production to Describe Microbial Biogeochemistry Over Time and Space in a Meromictic Pond

Vallino, Joseph J.; Huber, J. A.

doi:10.3389/fenvs.2018.00100

Cited by 21 publications

(21 citation statements)

References 89 publications

(100 reference statements)

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“…In some cases of oligotrophic waters dark, particle associated ROS production matches that of photoproduction . The notable difference in this case is that Sider's pond can exceed 2.5 mM dissolved sulfide (Vallino and Huber 2018). One potential pathway of ROS production under these conditions is through sulfide oxidation (Tapley et al 1999;Murphy et al 2016).…”

Section: Discussionmentioning

confidence: 92%

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New insights into the marine oxygen cycle from manganese oxide minerals and reactive oxygen species

Sutherland¹

2020

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The redox cycling of oxygen between O2, water, and intermediate redox states including hydrogen peroxide and superoxide, has profound impact on the availability and distribution of dissolved O2, the habitability of the marine biosphere, and cellular metabolic and physiological reactions that utilize O2. The sum total of processes that produce, consume, and exchange atoms with O2 in the atmosphere, oceans, and subsurface leave their isotopic fingerprints on the abundance of the three stable isotopes of O2 in the environment. In this thesis, I explore two aspects of the oxygen cycle in the past and present. First, I investigate the ability of manganese (Mn) oxide minerals to capture and retain the oxygen isotopic signature of dissolved O2 during the oxidation of aqueous Mn(II) to Mn-oxide minerals. I determine that approximately half of the oxygen atoms in Mn(III,IV) oxides I would like thank my committee, Colleen Hansel, Scott Wankel, and Kristin Bergmann for your academic guidance, feedback, and support in planning and executing my research. Thank you to Collin Ward for chairing my defense.Thanks to WHOI academic programs office for the many ways you've supported my work at WHOI and facilitated classes, research, and living between MIT and WHOI. Thank you to the wonderful team of admins in MC&G who have provided incredible help and assistance the last five years.Scott and Colleen, thank you for your mentorship, encouragement, and guidance in matters academic and otherwise over my time at WHOI. You have served as role models in and out of the lab, you gave me the freedom to pursue my own ideas, you have provided me with so many incredible research opportunities on land and at sea, and you have always been fierce advocates. Thank you for not giving up on me in year one when I almost destroyed both of your labs. Thank you for taking meetings at your dining room table and for blurring the lines between your lab children and your real children.

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Section: Discussionmentioning

confidence: 92%

“…In this study, we examine the production, fate, and abundance of dark superoxide and light and dark hydrogen peroxide in Sider's Pond, a meromictic brackish pond in Falmouth, MA (Vallino and Huber 2018). The pond transitions form oxic to sulfidic within several meters of the surface.…”

Section: Introductionmentioning

confidence: 99%

New insights into the marine oxygen cycle from manganese oxide minerals and reactive oxygen species

Sutherland¹

2020

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“…Protein synthesis rate is thus dependent on ATP concentration, but sufficient free-energy is dissipated for it to be considered an irreversible process. (5) The proteome is partitioned into three compartments: a ribosome compartment R, a metabolic protein compartment P, and a compartment for all other proteins required by the cell Q (termed "housekeeping"). As the housekeeping compartment is assumed to be constant, a direct trade-off between the fraction of the proteome dedicated to ribosomes and the fraction dedicated to metabolic proteins arises.…”

Section: Proteome Partitioningmentioning

confidence: 99%

“…Most notable of these is the maximum entropy production principle, that ecosystems tend towards states that produce entropy at the maximum achievable rate [ 3 ]. This principle has been applied to some degree of success to predicting ecosystem characteristics such as spatial distribution of vegetation [ 4 ] and biogeochemical cycling in ponds [ 5 ]. Though consideration of ecosystem wide entropy production has led to insights in areas such as the conditions for ecosystem stability [ 6 ], without detailed consideration of the underlying mechanisms, its explanatory potential remains limited.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic constraints on the assembly and diversity of microbial ecosystems are different near to and far from equilibrium

2021

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Non-equilibrium thermodynamics has long been an area of substantial interest to ecologists because most fundamental biological processes, such as protein synthesis and respiration, are inherently energy-consuming. However, most of this interest has focused on developing coarse ecosystem-level maximisation principles, providing little insight into underlying mechanisms that lead to such emergent constraints. Microbial communities are a natural system to decipher this mechanistic basis because their interactions in the form of substrate consumption, metabolite production, and cross-feeding can be described explicitly in thermodynamic terms. Previous work has considered how thermodynamic constraints impact competition between pairs of species, but restrained from analysing how this manifests in complex dynamical systems. To address this gap, we develop a thermodynamic microbial community model with fully reversible reaction kinetics, which allows direct consideration of free-energy dissipation. This also allows species to interact via products rather than just substrates, increasing the dynamical complexity, and allowing a more nuanced classification of interaction types to emerge. Using this model, we find that community diversity increases with substrate lability, because greater free-energy availability allows for faster generation of niches. Thus, more niches are generated in the time frame of community establishment, leading to higher final species diversity. We also find that allowing species to make use of near-to-equilibrium reactions increases diversity in a low free-energy regime. In such a regime, two new thermodynamic interaction types that we identify here reach comparable strengths to the conventional (competition and facilitation) types, emphasising the key role that thermodynamics plays in community dynamics. Our results suggest that accounting for realistic thermodynamic constraints is vital for understanding the dynamics of real-world microbial communities.

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“…MEP applications can be traced back to at least Paltridge [4], and perhaps to even Lotka [5], and MEP theory appears to have multiple origins [4,[6][7][8], but over the last decade and a half there has been increasing interest in extending MEP theory as well as its applications [9,10]. Since MEP makes no distinction between abiotic or biotic systems, MEP research has been wide ranging, from crystal growth [11], Rayleigh-Benard convection [12], phase transitions [13] to Earth's hydrologic cycle [14], ocean circulation [15], ecology [16], biogeochemistry [17] and evolution [18] to name just a few. The MEP approach has garnered interest in systems where classical reductionist modeling is difficult to implement due insufficient information or understanding, such as turbulent flow and living systems that are governed by selforganization.…”

Section: Introductionmentioning

confidence: 99%

Phytoplankton Temporal Strategies Increase Entropy Production in a Marine Food Web Model

Vallino

Tsakalakis

2020

Entropy

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We develop a trait-based model founded on the hypothesis that biological systems evolve and organize to maximize entropy production by dissipating chemical and electromagnetic free energy over longer time scales than abiotic processes by implementing temporal strategies. A marine food web consisting of phytoplankton, bacteria, and consumer functional groups is used to explore how temporal strategies, or the lack thereof, change entropy production in a shallow pond that receives a continuous flow of reduced organic carbon plus inorganic nitrogen and illumination from solar radiation with diel and seasonal dynamics. Results show that a temporal strategy that employs an explicit circadian clock produces more entropy than a passive strategy that uses internal carbon storage or a balanced growth strategy that requires phytoplankton to grow with fixed stoichiometry. When the community is forced to operate at high specific growth rates near 2 d−1, the optimization-guided model selects for phytoplankton ecotypes that exhibit complementary for winter versus summer environmental conditions to increase entropy production. We also present a new type of trait-based modeling where trait values are determined by maximizing entropy production rather than by random selection.

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Using Maximum Entropy Production to Describe Microbial Biogeochemistry Over Time and Space in a Meromictic Pond

Cited by 21 publications

References 89 publications

New insights into the marine oxygen cycle from manganese oxide minerals and reactive oxygen species

New insights into the marine oxygen cycle from manganese oxide minerals and reactive oxygen species

Thermodynamic constraints on the assembly and diversity of microbial ecosystems are different near to and far from equilibrium

Phytoplankton Temporal Strategies Increase Entropy Production in a Marine Food Web Model

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