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Peoples LM, Isanta-Navarro J, Bras B, Hand BK, Rosenzweig F, Elser JJ, Church MJ. Physiology, fast and slow: bacterial response to variable resource stoichiometry and dilution rate. mSystems 2024; 9:e0077024. [PMID: 38980051 PMCID: PMC11334502 DOI: 10.1128/msystems.00770-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 06/19/2024] [Indexed: 07/10/2024] Open
Abstract
Microorganisms grow despite imbalances in the availability of nutrients and energy. The biochemical and elemental adjustments that bacteria employ to sustain growth when these resources are suboptimal are not well understood. We assessed how Pseudomonas putida KT2440 adjusts its physiology at differing dilution rates (to approximate growth rates) in response to carbon (C), nitrogen (N), and phosphorus (P) stress using chemostats. Cellular elemental and biomolecular pools were variable in response to different limiting resources at a slow dilution rate of 0.12 h-1, but these pools were more similar across treatments at a faster rate of 0.48 h-1. At slow dilution rates, limitation by P and C appeared to alter cell growth efficiencies as reflected by changes in cellular C quotas and rates of oxygen consumption, both of which were highest under P- and lowest under C- stress. Underlying these phenotypic changes was differential gene expression of terminal oxidases used for ATP generation that allows for increased energy generation efficiency. In all treatments under fast dilution rates, KT2440 formed aggregates and biofilms, a physiological response that hindered an accurate assessment of growth rate, but which could serve as a mechanism that allows cells to remain in conditions where growth is favorable. Our findings highlight the ways that microorganisms dynamically adjust their physiology under different resource supply conditions, with distinct mechanisms depending on the limiting resource at slow growth and convergence toward an aggregative phenotype with similar compositions under conditions that attempt to force fast growth. IMPORTANCE All organisms experience suboptimal growth conditions due to low nutrient and energy availability. Their ability to survive and reproduce under such conditions determines their evolutionary fitness. By imposing suboptimal resource ratios under different dilution rates on the model organism Pseudomonas putida KT2440, we show that this bacterium dynamically adjusts its elemental composition, morphology, pools of biomolecules, and levels of gene expression. By examining the ability of bacteria to respond to C:N:P imbalance, we can begin to understand how stoichiometric flexibility manifests at the cellular level and impacts the flow of energy and elements through ecosystems.
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Affiliation(s)
- Logan M. Peoples
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Jana Isanta-Navarro
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Benedicta Bras
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Brian K. Hand
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Frank Rosenzweig
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - James J. Elser
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Matthew J. Church
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
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2
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Li T, Xu L, Li W, Wang C, Gin KYH, Chai X, Wu B. Dissolved organic carbon spurs bacterial-algal competition and phosphorus-paucity adaptation: Boosting Microcystis' phosphorus uptake capacity. WATER RESEARCH 2024; 255:121465. [PMID: 38569356 DOI: 10.1016/j.watres.2024.121465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 02/26/2024] [Accepted: 03/12/2024] [Indexed: 04/05/2024]
Abstract
Dissolved organic carbon (DOC) can alter the availability of background nutrients by affecting the proliferation of heterotrophic bacteria, which exerts a notable influence on algal growth and metabolism. However, the mechanism of how allochthonous DOC (aDOC) precipitates shifts in bacterial-algal interactions and modulates the occurrence of cyanobacteria blooms remains inadequately elucidated. Therefore, this study investigated the relationship between bacteria and algae under aDOC stimulation. We found that excess aDOC triggered the breakdown and reestablishment of the equilibrium between Microcystis and heterotrophic bacteria. The rapid proliferation of heterotrophic bacteria led to a dramatic decrease in soluble phosphorus and thereby resulted in the inhibition of the Microcystis growth. When the available DOC was depleted, the rapid death of heterotrophic bacteria released large amounts of dissolved phosphorus, which provided sufficient nutrients for the recovery of Microcystis. Notably, Microcystis rejuvenated and showed higher cell density compared to the carbon-absent group. This phenomenon can be ascribed that Microcystis regulated the compositions of extracellular polymeric substances (EPS) and the expression of relevant proteins to adapt to a nutrient-limited environment. Using time of flight secondary ion mass spectrometry (TOF-SIM) and proteomic analysis, we observed an enhancement of the signal of organic matter and metal ions associated with P complexation in EPS. Moreover, Microcystis upregulated proteins related to organic phosphorus transformation to increase the availability of phosphorus in various forms. In summary, this study emphasized the role of DOC in algal blooms, revealing the underestimated enhancement of Microcystis nutrient utilization through DOC-induced heterotrophic competition and providing valuable insights into eutrophication management and control.
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Affiliation(s)
- Tingting Li
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Longqian Xu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Wenxuan Li
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; State Environmental Protection Key Laboratory of Ecological Effect and Risk Assessment of Chemicals, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Chengxian Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Karina Yew-Hoong Gin
- NUS Environmental Research Institute, National University of Singapore, 1 Create Way, #15-02, Singapore, 138602, Singapore
| | - Xiaoli Chai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Boran Wu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
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3
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Brison A, Rossi P, Derlon N. Influent carbon to phosphorus ratio drives the selection of PHA-storing organisms in a single CSTR. WATER RESEARCH X 2022; 16:100150. [PMID: 35965889 PMCID: PMC9364015 DOI: 10.1016/j.wroa.2022.100150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/29/2022] [Accepted: 07/29/2022] [Indexed: 06/01/2023]
Abstract
Enriching a biomass with a high fraction of polyhydroxyalkanoate-storing organisms (PHA-storers) represents an essential step in the production of PHAs (bioplastics) from municipal wastewater using mixed microbial cultures. A major challenge is however to create selective growth conditions that are favourable to PHA-storers. Our study thus investigates to what extent the influent COD to phosphorus (COD:P) ratio can be used as a tool for the robust selection of PHA-storers in a single continuous-flow stirred-tank reactor (CSTR). Therefore, we operated five CSTRs in parallel, fed with synthetic wastewater (50% acetate - 50% propionate) with different COD:P ratios (200-1000 gCOD gP-1), and performed a detailed analysis of the microbial communities over long-term (30-70 solid retention times). Our study demonstrates that efficient and robust selection of PHA-storers can be achieved in a single CSTR at high influent COD:P ratios. The selective advantage for PHA-storers increases with the influent COD:P ratio, but only if growth conditions remain limited by both C-substrate and P. In contrast, selection performance deteriorates when COD:P ratios are too high and growth conditions are limited by P only. At an optimal COD:P ratio of 800 gCOD gP-1, a stable microbial community consisting of >90% PHA-storers and dominated by Pannonibacter sp. was selected in the long-term. Finally, our results suggest that high COD:P ratios provide a selective advantage to microorganisms with low cellular P requirements, explaining why different PHA-storers (i.e., Xanthobacter sp. vs. Pannonibacter sp.) were selected depending on the influent COD:P ratio (i.e., 200 vs. 800 gCOD gP-1). Overall, our results provide relevant insights for the development of a new approach for selecting PHA-storers, based on the use of a single CSTR and control of the influent COD:P ratio.
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Affiliation(s)
- Antoine Brison
- ETH Zürich, Institute of Environmental Engineering, Zürich 8093, Switzerland
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf 8600, Switzerland
| | - Pierre Rossi
- Central Environmental Laboratory, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne Lausanne, Switzerland
| | - Nicolas Derlon
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf 8600, Switzerland
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4
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Microbial storage and its implications for soil ecology. THE ISME JOURNAL 2022; 16:617-629. [PMID: 34593996 PMCID: PMC8857262 DOI: 10.1038/s41396-021-01110-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 08/31/2021] [Accepted: 09/07/2021] [Indexed: 02/08/2023]
Abstract
Organisms throughout the tree of life accumulate chemical resources, in particular forms or compartments, to secure their availability for future use. Here we review microbial storage and its ecological significance by assembling several rich but disconnected lines of research in microbiology, biogeochemistry, and the ecology of macroscopic organisms. Evidence is drawn from various systems, but we pay particular attention to soils, where microorganisms play crucial roles in global element cycles. An assembly of genus-level data demonstrates the likely prevalence of storage traits in soil. We provide a theoretical basis for microbial storage ecology by distinguishing a spectrum of storage strategies ranging from surplus storage (storage of abundant resources that are not immediately required) to reserve storage (storage of limited resources at the cost of other metabolic functions). This distinction highlights that microorganisms can invest in storage at times of surplus and under conditions of scarcity. We then align storage with trait-based microbial life-history strategies, leading to the hypothesis that ruderal species, which are adapted to disturbance, rely less on storage than microorganisms adapted to stress or high competition. We explore the implications of storage for soil biogeochemistry, microbial biomass, and element transformations and present a process-based model of intracellular carbon storage. Our model indicates that storage can mitigate against stoichiometric imbalances, thereby enhancing biomass growth and resource-use efficiency in the face of unbalanced resources. Given the central roles of microbes in biogeochemical cycles, we propose that microbial storage may be influential on macroscopic scales, from carbon cycling to ecosystem stability.
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5
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Osburn FS, Wagner ND, Scott JT. Biological stoichiometry and growth dynamics of a diazotrophic cyanobacteria in nitrogen sufficient and deficient conditions. HARMFUL ALGAE 2021; 103:102011. [PMID: 33980450 PMCID: PMC8119935 DOI: 10.1016/j.hal.2021.102011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
The role of nitrogen (N) fixation in determining the frequency, magnitude, and extent of harmful algal blooms (HABs) has not been well studied. Dolichospermum is a common HAB species that is diazotrophic (capable of N fixation) and thus growth is often considered never to be limited by low combined N sources. However, N fixation is energetically expensive and its cost during bloom formation has not been quantified. Additionally, it is unknown how acclimation to differing nutrient ratios affects growth and cellular carbon (C):N stoichiometry. Here, we test the hypotheses that diazotrophic cyanobacteria are homeostatic for N because of their ability to fix atmospheric N2 and that previous acclimation to low N environments will result in more fixed N and lower C:N stoichiometry. Briefly, cultures that varied in resource N:phosphorus (P) ranging from 0.01 to 100 (atom), were seeded with Dolichospermum which were previously acclimated to low and high N:P conditions and then sampled temporally for growth and C:N stoichiometry. We found that Dolichospermum was not homeostatic for N and displayed classic signs of N limitation and elevated C:N stoichiometry, highlighting the necessary growth trade-off within cells when expending energy to fix N. Acclimation to N limited conditions caused differences in both C:N and fixed N at various time points in the experiment. These results highlight the importance of environmentally available N to a diazotrophic bloom, as well as how previous growth conditions can influence population growth during blooms experiencing variable N:P.
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Affiliation(s)
- Felicia S Osburn
- Department of Biology, Baylor University, One Bear Place 97388, Waco, TX 76798, USA; Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA.
| | - Nicole D Wagner
- Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA
| | - J Thad Scott
- Department of Biology, Baylor University, One Bear Place 97388, Waco, TX 76798, USA; Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA
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6
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Available Dissolved Organic Carbon Alters Uptake and Recycling of Phosphorus and Nitrogen from River Sediments. WATER 2020. [DOI: 10.3390/w12123321] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Concurrent with nutrient pollution, agriculture has significantly impacted the quantity, composition, and bioavailability of catchment-derived dissolved organic carbon (DOC) in stream ecosystems. Based on the stoichiometric theory, we tested the hypothesis that bioavailable DOC will stimulate the heterotrophic uptake of soluble reactive P (SRP) and inorganic nitrogen in stream sediments. In a simplified laboratory column flow-through study, we exposed stream sediments to additions of glucose, nitrate, and phosphate alone and in combination (+C, +NP, +CNP), and calculated gross and net changes in DOC and nutrients via a mass balance approach. Our results show that glucose-C increased nutrient uptake, but also that NP additions resulted in the enhanced consumption of both native and added organic C. The effects of C addition were stronger on N than P uptake, presumably because labile C stimulated both assimilation and denitrification, while part of the P uptake was due to adsorption. Internal cycling affected net nutrient uptake due to losses of dissolved organically-complexed P and N (DOP and DON). Overall, our study shows that increases in the stoichiometric availability of organic carbon can stimulate N and P sequestration in nutrient-polluted stream sediments. Future studies are required to assess the effects of complex organic carbon sources on nutrient uptake in stream sediments under different environmental conditions, and whether these stoichiometric relations are relevant for ecosystem management.
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7
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Roberts WM, George TS, Stutter MI, Louro A, Ali M, Haygarth PM. Phosphorus leaching from riparian soils with differing management histories under three grass species. JOURNAL OF ENVIRONMENTAL QUALITY 2020; 49:74-84. [PMID: 33016354 DOI: 10.1002/jeq2.20037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/15/2019] [Indexed: 06/11/2023]
Abstract
Plants release carbon-based exudates from their roots into the rhizosphere to increase phosphorus (P) supply to the soil solution. However, if more P than required is brought into solution, additional P could be available for leaching from riparian soils. To investigate this further, soil columns containing a riparian arable and buffer strip soil, which differed in organic matter contents, were sown with three common agricultural and riparian grass species. The P loads in leachate were measured and compared with those from unplanted columns, which were 0.17 ± 0.01 and 0.89 ± 0.04 mg kg-1 for the arable and buffer strip soil, respectively. A mixture of ryegrass and red fescue significantly (p ≤ .05) increased dissolved inorganic P loads in leachate from the arable (0.23 ± 0.01 mg kg-1 ) and buffer strip soil (1.06 ± 0.05 mg kg-1 ), whereas barley significantly reduced P leaching from the buffer strip soil (0.53 ± 0.08 mg kg-1 ). This was dependent on the dissolved organic C released under different plant species and on interactions with soil management history and biogeochemical conditions, rather than on plant uptake of P and accumulation into biomass. This suggested that the amount and forms of P present in the soil and the ability of the plants to mobilize them could be key factors in determining how plants affect leaching of soil P. Selecting grass species for different stages of buffer strip development, basing species selection on root physiological traits, and correcting soil nutrient stoichiometry in riparian soils through vegetative mining could help to lower this contribution.
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Affiliation(s)
- William M Roberts
- Lancaster Environment Centre, Lancaster Univ., Lancaster, LA1 4YQ, UK
- The James Hutton Institute, Aberdeen, AB15 8QH, UK
- Univ. of Chichester Business School, Bognor Regis Campus, Upper Bognor Rd., Bognor Regis, West Sussex, PO21 1HR, UK
| | | | - Marc I Stutter
- Lancaster Environment Centre, Lancaster Univ., Lancaster, LA1 4YQ, UK
- The James Hutton Institute, Aberdeen, AB15 8QH, UK
| | - Aránzazu Louro
- Rothamsted Research, North Wyke, Okehampton, Devon, EX20 2SB, UK
| | - Mustafa Ali
- Lancaster Environment Centre, Lancaster Univ., Lancaster, LA1 4YQ, UK
| | - Philip M Haygarth
- Lancaster Environment Centre, Lancaster Univ., Lancaster, LA1 4YQ, UK
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8
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Ren Z, Martyniuk N, Oleksy IA, Swain A, Hotaling S. Ecological Stoichiometry of the Mountain Cryosphere. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00360] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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9
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Manzella M, Geiss R, Hall EK. Evaluating the stoichiometric trait distributions of cultured bacterial populations and uncultured microbial communities. Environ Microbiol 2019; 21:3613-3626. [PMID: 31090973 DOI: 10.1111/1462-2920.14684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 10/26/2022]
Abstract
We measured the stoichiometric trait distribution of cultured freshwater bacterial populations under different resource conditions and compared them to natural microbial communities sampled from three lakes. Trait distributions showed population differences among growth phases and community differences among lakes that would have been masked by only reporting the mean biomass value. The stoichiometric trait distribution of the environmental isolates changed with P availability, growth phase and genotype, with P availability having the strongest effect. The distribution of biomass ratios within each isolate growth experiment were the most constrained during the stages of rapid growth and commonly had unimodal distributions. In contrast to the population distributions, the distribution of N:P and C:P for a similar number of cells from each of the lake communities had narrower stoichiometric distributions and more commonly exhibited multiple modes. © 2019 Society for Applied Microbiology and John Wiley & Sons Ltd.
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Affiliation(s)
- Michael Manzella
- Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO, 80523, USA.,Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - Roy Geiss
- Central Instrument Facility, Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA
| | - Ed K Hall
- Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO, 80523, USA.,Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80523, USA
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10
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Godwin CM, Whitaker EA, Cotner JB. Growth rate and resource imbalance interactively control biomass stoichiometry and elemental quotas of aquatic bacteria. Ecology 2018; 98:820-829. [PMID: 27995610 DOI: 10.1002/ecy.1705] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/01/2016] [Accepted: 11/29/2016] [Indexed: 11/09/2022]
Abstract
The effects of resource stoichiometry and growth rate on the elemental composition of biomass have been examined in a wide variety of organisms, but the interaction among these effects is often overlooked. To determine how growth rate and resource imbalance affect bacterial carbon (C): nitrogen (N): phosphorus (P) stoichiometry and elemental content, we cultured two strains of aquatic heterotrophic bacteria in chemostats at a range of dilution rates and P supply levels (C:P of 100:1 to 10,000:1). When growing below 50% of their maximum growth rate, P availability and dilution rate had strong interactive effects on biomass C:N:P, elemental quotas, cell size, respiration rate, and growth efficiency. In contrast, at faster growth rates, biomass stoichiometry was strongly homeostatic in both strains (C:N:P of 70:13:1 and 73:14:1) and elemental quotas of C, N, and P were tightly coupled (but not constant). Respiration and cell size increased with both growth rate and P limitation, and P limitation induced C accumulation and excess respiration. These results show that bacterial biomass stoichiometry is relatively constrained when all resources are abundant and growth rates are high, but at low growth rates resource imbalance is relatively more important than growth rate in controlling bacterial biomass composition.
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Affiliation(s)
- Casey M Godwin
- Department of Ecology, Evolution, and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, Minnesota, 55108, USA
| | - Emily A Whitaker
- Department of Ecology, Evolution, and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, Minnesota, 55108, USA
| | - James B Cotner
- Department of Ecology, Evolution, and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, Minnesota, 55108, USA
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11
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Stutter MI, Graeber D, Evans CD, Wade AJ, Withers PJA. Balancing macronutrient stoichiometry to alleviate eutrophication. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 634:439-447. [PMID: 29631134 DOI: 10.1016/j.scitotenv.2018.03.298] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 06/08/2023]
Abstract
Reactive nitrogen (N) and phosphorus (P) inputs to surface waters modify aquatic environments, affect public health and recreation. Source controls dominate eutrophication management, whilst biological regulation of nutrients is largely neglected, although aquatic microbial organisms have huge potential to process nutrients. The stoichiometric ratio of organic carbon (OC) to N to P atoms should modulate heterotrophic pathways of aquatic nutrient processing, as high OC availability favours aquatic microbial processing. Heterotrophic microbial processing removes N by denitrification and captures N and P as organically-complexed, less eutrophying forms. With a global data synthesis, we show that the atomic ratios of bioavailable dissolved OC to either N or P in rivers with urban and agricultural land use are often distant from a "microbial optimum". This OC-deficiency relative to high availabilities of N and P likely overwhelms within-river heterotrophic processing. We propose that the capability of streams and rivers to retain N and P may be improved by active stoichiometric rebalancing. Although autotrophic OC production contributes to heterotrophic rates substantial control on nutrient processing from allochthonous OC is documented for N and an emerging field for P. Hence, rebalancing should be done by reconnecting appropriate OC sources such as wetlands and riparian forests that have become disconnected from rivers concurrent with agriculture and urbanisation. However, key knowledge gaps require research prior to the safe implementation of this approach in management: (i) to evaluate system responses to catchment inputs of dissolved OC forms and amounts relative to internal production of autotrophic dissolved OC and aquatic and terrestrial particulate OC and (ii) evaluate risk factors in anoxia-mediated P desorption with elevated OC scenarios. Still, we find stoichiometric rebalancing through reconnecting landscape beneficial OC sources has considerable potential for river management to alleviate eutrophication, improve water quality and aquatic ecosystem health, if augmenting nutrient source control.
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Affiliation(s)
- M I Stutter
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
| | - D Graeber
- Aquatic Ecosystem Analysis, Helmholtz Centre for Environmental Research, Magdeburg, Germany
| | - C D Evans
- Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK
| | - A J Wade
- Dept. of Archaeology, Geography and Environmental Science, University of Reading, Reading RG6 6AB, UK
| | - P J A Withers
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
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12
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Malerba ME, Palacios MM, Marshall DJ. Do larger individuals cope with resource fluctuations better? An artificial selection approach. Proc Biol Sci 2018; 285:rspb.2018.1347. [PMID: 30068687 DOI: 10.1098/rspb.2018.1347] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 07/11/2018] [Indexed: 11/12/2022] Open
Abstract
Size determines the rate at which organisms acquire and use resources but it is unclear what size should be favoured under unpredictable resource regimes. Some theories claim smaller organisms can grow faster following a resource pulse, whereas others argue larger species can accumulate more resources and maintain growth for longer periods between resource pulses. Testing these theories has relied on interspecific comparisons, which tend to confound body size with other life-history traits. As a more direct approach, we used 280 generations of artificial selection to evolve a 10-fold difference in mean body size between small- and large-selected phytoplankton lineages of Dunaliella tertiolecta, while controlling for biotic and abiotic variables. We then quantified how body size affected the ability of this species to grow at nutrient-replete conditions and following periods of nitrogen or phosphorous deprivation. Overall, smaller cells showed slower growth, lower storage capacity and poorer recovery from phosphorous depletion, as predicted by the 'fasting endurance hypothesis'. However, recovery from nitrogen limitation was independent of size-a finding unanticipated by current theories. Phytoplankton species are responsible for much of the global carbon fixation and projected trends of cell size decline could reduce primary productivity by lowering the ability of a cell to store resources.
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Affiliation(s)
- Martino E Malerba
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia .,School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| | - Maria M Palacios
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.,School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| | - Dustin J Marshall
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.,School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
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13
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Godwin CM, Cotner JB. What intrinsic and extrinsic factors explain the stoichiometric diversity of aquatic heterotrophic bacteria? THE ISME JOURNAL 2018; 12:598-609. [PMID: 29171840 PMCID: PMC5776474 DOI: 10.1038/ismej.2017.195] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 09/07/2017] [Accepted: 10/09/2017] [Indexed: 11/08/2022]
Abstract
The elemental content of microbial communities is dependent upon the physiology of constituent populations, yet ecological stoichiometry has made slow progress toward identifying predictors of how species and strains change the elemental content of their biomass in response to the stoichiometry of elements in resources. We asked whether the elemental content of aquatic bacteria, especially flexibility in elemental content, could be predicted by their phylogeny, maximum growth rate or lake productivity. We examined 137 isolates using chemostats and found that strains differed substantially in how the carbon:nitrogen:phosphorus ratios (C:N:P) in their biomass responded to P-sufficient and P-limiting conditions. The median strain increased its biomass C:N:P from 68:14:1 to 164:25:1 under P limitation. Patterns in elemental content and ratios were partly explained by phylogeny, yet flexibility in elemental content showed no phylogenetic signal. The growth rate hypothesis predicts that P content is positively related to growth rate, but we found weak correlation between maximum growth rate and P content among the strains. Overall, isolates from highly productive lakes had higher maximum growth rates and less flexible biomass N:P than isolates from unproductive lakes. These results show that bacteria present within lake communities exhibit diverse strategies for responding to elemental imbalance.
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Affiliation(s)
- Casey M Godwin
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, USA
| | - James B Cotner
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN, USA
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14
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Phillips KN, Godwin CM, Cotner JB. The Effects of Nutrient Imbalances and Temperature on the Biomass Stoichiometry of Freshwater Bacteria. Front Microbiol 2017; 8:1692. [PMID: 28943865 PMCID: PMC5596061 DOI: 10.3389/fmicb.2017.01692] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 08/22/2017] [Indexed: 11/21/2022] Open
Abstract
Two contemporary effects of humans on aquatic ecosystems are increasing temperatures and increasing nutrient concentrations from fertilizers. The response of organisms to these perturbations has important implications for ecosystem processes. We examined the effects of phosphorus (P) supply and temperature on organismal carbon, nitrogen and phosphorus (C, N, and P) content, cell size and allocation into internal P pools in three strains of recently isolated bacteria (Agrobacterium sp., Flavobacterium sp., and Arthrobacter sp.). We manipulated resource C:P in chemostats and also manipulated temperatures from 10 to 30°C. Dilution rates were maintained for all the strains at ~25% of their temperature-specific maximum growth rate to simulate low growth rates in natural systems. Under these conditions, there were large effects of resource stoichiometry and temperature on biomass stoichiometry, element quotas, and cell size. Each strain was smaller when C-limited and larger when P-limited. Temperature had weak effects on morphology, little effect on C quotas, no effect on N quotas and biomass C:N, but had strong effects on P quotas, biomass N:P and C:P, and RNA. RNA content per cell increased with increasing temperature at most C:P supply ratios, but was more strongly affected by resource stoichiometry than temperature. Because we used a uniform relative growth rate across temperatures, these findings mean that there are important nutrient and temperature affects on biomass composition and stoichiometry that are independent of growth rate. Changes in biomass stoichiometry with temperature were greatest at low P availability, suggesting tighter coupling between temperature and biomass stoichiometry in oligotrophic ecosystems than in eutrophic systems. Because the C:P stoichiometry of biomass affects how bacteria assimilate and remineralize C, increased P availability could disrupt a negative feedback between biomass stoichiometry and C availability.
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Affiliation(s)
- Katherine N Phillips
- Department of Ecology, Evolution and Behavior, University of MinnesotaSt. Paul, MN, United States.,Science Department, Saint Paul CollegeSaint Paul, MN, United States
| | - Casey M Godwin
- Department of Ecology, Evolution and Behavior, University of MinnesotaSt. Paul, MN, United States.,School of Natural Resources and Environment, University of MichiganAnn Arbor, MI, United States
| | - James B Cotner
- Department of Ecology, Evolution and Behavior, University of MinnesotaSt. Paul, MN, United States
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15
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Manzoni S, Čapek P, Mooshammer M, Lindahl BD, Richter A, Šantrůčková H. Optimal metabolic regulation along resource stoichiometry gradients. Ecol Lett 2017; 20:1182-1191. [DOI: 10.1111/ele.12815] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 05/07/2017] [Accepted: 06/30/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Stefano Manzoni
- Department of Physical Geography and Bolin Centre for Climate Research; Stockholm University; Stockholm Sweden
| | - Petr Čapek
- Department of Ecosystem Biology; University of South Bohemia; České Budějovice Czech Republic
| | - Maria Mooshammer
- Department of Microbiology and Ecosystem Science; University of Vienna; Vienna Austria
| | - Björn D. Lindahl
- Department of Soil and Environment; Swedish University of Agricultural Sciences; Uppsala Sweden
| | - Andreas Richter
- Department of Microbiology and Ecosystem Science; University of Vienna; Vienna Austria
| | - Hana Šantrůčková
- Department of Ecosystem Biology; University of South Bohemia; České Budějovice Czech Republic
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16
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Stenzel B, Rofner C, Pérez MT, Sommaruga R. Stoichiometry of natural bacterial assemblages from lakes located across an elevational gradient. Sci Rep 2017; 7:5875. [PMID: 28725017 PMCID: PMC5517659 DOI: 10.1038/s41598-017-06282-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 06/09/2017] [Indexed: 11/16/2022] Open
Abstract
Heterotrophic bacteria are thought to be phosphorus-rich organisms with relatively homeostatic stoichiometry, but the elemental composition of natural bacterial communities has rarely been assessed. Here we tested whether bacterial stoichiometry changes with the trophic status of lakes by assessing the elemental composition of the bacterial-dominated (hereafter microbial) fraction together with that of the dissolved and seston fractions in 11 lakes situated along an elevational gradient. The stoichiometry of these three size-fractions was analyzed during the thermal stratification and mixing periods in composite water samples and in the water layer of the deep chlorophyll-a maximum. In addition, we analyzed the relative abundance of the most common bacterial groups in the lakes. Our results show that the microbial fraction was always enriched in phosphorus compared to the dissolved fraction, irrespectively of the lake trophic status. Further, they indicate that the elemental composition of bacteria in mountain lakes is at least seasonally very dynamic, resulting not only from changes in the nutrient ratios of the resource itself, but probably from changes in the composition of the dominant bacterial taxa too, though at the taxonomic level analyzed, we did not find evidence for this.
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Affiliation(s)
- Birgit Stenzel
- University of Innsbruck, Institute of Ecology, Technikerstraße 25, 6020, Innsbruck, Austria
| | - Carina Rofner
- University of Innsbruck, Institute of Ecology, Technikerstraße 25, 6020, Innsbruck, Austria
| | - Maria Teresa Pérez
- University of Innsbruck, Institute of Ecology, Technikerstraße 25, 6020, Innsbruck, Austria
| | - Ruben Sommaruga
- University of Innsbruck, Institute of Ecology, Technikerstraße 25, 6020, Innsbruck, Austria.
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17
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Zaarur S, Wang DT, Ono S, Bosak T. Influence of Phosphorus and Cell Geometry on the Fractionation of Sulfur Isotopes by Several Species of Desulfovibrio during Microbial Sulfate Reduction. Front Microbiol 2017; 8:890. [PMID: 28611734 PMCID: PMC5447228 DOI: 10.3389/fmicb.2017.00890] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 05/02/2017] [Indexed: 12/02/2022] Open
Abstract
We investigated the influence of organic substrates and phosphate concentration on the rates of dissimilatory microbial sulfate reduction and the 34S/32S isotopic fractionation produced by several Desulfovibrio species. Our experiments corroborate the previously reported species-specific correlation between sulfur isotope fractionation and cell-specific sulfate reduction rates. We also identify cell size as a key factor that contributes to the species-effect of this correlation. Phosphate limitation results in larger cells and contributes to a small decrease in sulfur isotope fractionation concomitant with an apparent increase in cell-specific sulfate reduction rates. Sulfur isotope fractionation in phosphate-limited cultures asymptotically approaches a lower limit of approximately 5‰ as cell-specific sulfate reduction rates increase to >100 fmol cell−1 day−1. These experimental results test models that link the reversibilities of enzymatic steps in dissimilatory sulfate reduction to sulfur isotope fractionation and show that these models can provide consistent predictions across large variations in physiological states experienced by sulfate reducing bacteria.
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Affiliation(s)
- Shikma Zaarur
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of TechnologyCambridge, MA, United States
| | - David T Wang
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of TechnologyCambridge, MA, United States
| | - Shuhei Ono
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of TechnologyCambridge, MA, United States
| | - Tanja Bosak
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of TechnologyCambridge, MA, United States
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18
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Trautwein K, Feenders C, Hulsch R, Ruppersberg HS, Strijkstra A, Kant M, Vagts J, Wünsch D, Michalke B, Maczka M, Schulz S, Hillebrand H, Blasius B, Rabus R. Non-Redfield, nutrient synergy and flexible internal elemental stoichiometry in a marine bacterium. FEMS Microbiol Ecol 2017; 93:3806670. [PMID: 28486660 PMCID: PMC5458051 DOI: 10.1093/femsec/fix059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 05/04/2017] [Indexed: 01/01/2023] Open
Abstract
The stoichiometric constraints of algal growth are well understood, whereas there is less knowledge for heterotrophic bacterioplankton. Growth of the marine bacterium Phaeobacter inhibens DSM 17395, belonging to the globally distributed Roseobacter group, was studied across a wide concentration range of NH4+ and PO43-. The unique dataset covers 415 different concentration pairs, corresponding to 207 different molar N:P ratios (from 10-2 to 105). Maximal growth (by growth rate and biomass yield) was observed within a restricted concentration range at N:P ratios (∼50-120) markedly above Redfield. Experimentally determined growth parameters deviated to a large part from model predictions based on Liebig's law of the minimum, thus implicating synergistic co-limitation due to biochemical dependence of resources. Internal elemental ratios of P. inhibens varied with external nutrient supply within physiological constraints, thus adding to the growing evidence that aquatic bacteria can be flexible in their internal elemental composition. Taken together, the findings reported here revealed that P. inhibens is well adapted to fluctuating availability of inorganic N and P, expected to occur in its natural habitat (e.g. colonized algae, coastal areas). Moreover, this study suggests that elemental variability in bacterioplankton needs to be considered in the ecological stoichiometry of the oceans.
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Affiliation(s)
- Kathleen Trautwein
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Christoph Feenders
- Mathematical Modelling, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Reiner Hulsch
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Hanna S. Ruppersberg
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Annemieke Strijkstra
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Mirjam Kant
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Jannes Vagts
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Daniel Wünsch
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Bernhard Michalke
- Research Unit Analytical Biogeochemistry, HelmholtzZentrum München, Neuherberg 85764, Germany
| | - Michael Maczka
- Institute for Organic Chemistry, Technische Universität Carolo-Wilhelmina, Braunschweig 38106, Germany
| | - Stefan Schulz
- Institute for Organic Chemistry, Technische Universität Carolo-Wilhelmina, Braunschweig 38106, Germany
| | - Helmut Hillebrand
- Department of Planktology, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, Oldenburg 26111, Germany
| | - Bernd Blasius
- Mathematical Modelling, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
| | - Ralf Rabus
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment (ICBM), University Oldenburg, Oldenburg 26111, Germany
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19
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Manzoni S. Flexible Carbon-Use Efficiency across Litter Types and during Decomposition Partly Compensates Nutrient Imbalances-Results from Analytical Stoichiometric Models. Front Microbiol 2017; 8:661. [PMID: 28491054 PMCID: PMC5405148 DOI: 10.3389/fmicb.2017.00661] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/31/2017] [Indexed: 11/13/2022] Open
Abstract
Mathematical models involving explicit representations of microbial processes have been developed to infer microbial community properties from laboratory and field measurements. While this approach has been used to estimate the kinetic constants related to microbial activity, it has not been fully exploited for inference of stoichiometric traits, such as carbon-use efficiency (CUE). Here, a hierarchy of analytically-solvable mass-balance models of litter carbon (C) and nitrogen (N) dynamics is developed, to infer decomposer CUE from measured C and N contents during litter decomposition. The models are solved in the phase space—expressing litter remaining N as a function of remaining C—rather than in time, thus focusing on the stoichiometric relations during decomposition rather than the kinetics of degradation. This approach leads to explicit formulas that depend on CUE and other microbial properties, which can then be treated as model parameters and retrieved via nonlinear regression. CUE is either assumed time-invariant or as a function of the fraction of remaining litter C as a substitute for time. In all models, CUE tends to increase with increasing litter N availability across a range of litter types. When temporal trends in CUE are considered, CUE increases during decomposition of N-poor litter cohorts, in which decomposers are initially N-limited, but decreases in N-rich litter possibly due to C-limitation. These patterns of flexible CUE that partly compensate stoichiometric imbalances are robust to moderate shifts in decomposer C:N ratio and hold across wide climatic gradients.
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Affiliation(s)
- Stefano Manzoni
- Department of Physical Geography, Stockholm UniversityStockholm, Sweden.,Bolin Centre for Climate Research, Stockholm UniversityStockholm, Sweden
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20
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Jeyasingh PD, Goos JM, Thompson SK, Godwin CM, Cotner JB. Ecological Stoichiometry beyond Redfield: An Ionomic Perspective on Elemental Homeostasis. Front Microbiol 2017; 8:722. [PMID: 28487686 PMCID: PMC5403914 DOI: 10.3389/fmicb.2017.00722] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/07/2017] [Indexed: 11/13/2022] Open
Abstract
Elemental homeostasis has been largely characterized using three important elements that were part of the Redfield ratio (i.e., carbon: nitrogen: phosphorus). These efforts have revealed substantial diversity in homeostasis among taxonomic groups and even within populations. Understanding the evolutionary basis, and ecological consequences of such diversity is a central challenge. Here, we propose that a more complete understanding of homeostasis necessitates the consideration of other elements beyond C, N, and P. Specifically, we posit that physiological complexity underlying maintenance of elemental homeostasis along a single elemental axis impacts processing of other elements, thus altering elemental homeostasis along other axes. Indeed, transcriptomic studies in a wide variety of organisms have found that individuals differentially express significant proportions of the genome in response to variability in supply stoichiometry in order to maintain varying levels of homeostasis. We review the literature from the emergent field of ionomics that has established the consequences of such physiological trade-offs on the content of the entire suite of elements in an individual. Further, we present experimental data on bacteria exhibiting divergent phosphorus homeostasis phenotypes demonstrating the fundamental interconnectedness among elemental quotas. These observations suggest that physiological adjustments can lead to unexpected patterns in biomass stoichiometry, such as correlated changes among suites of non-limiting microelements in response to limitation by macroelements. Including the entire suite of elements that comprise biomass will foster improved quantitative understanding of the links between chemical cycles and the physiology of organisms.
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Affiliation(s)
- Punidan D Jeyasingh
- Department of Integrative Biology, Oklahoma State UniversityStillwater, OK, USA
| | - Jared M Goos
- Department of Biology, University of Texas at ArlingtonArlington, TX, USA
| | - Seth K Thompson
- Water Resources Science Program, University of MinnesotaSt. Paul, MN, USA
| | - Casey M Godwin
- School of Natural Resources and Environment, University of MichiganAnn Arbor, MI, USA
| | - James B Cotner
- Department of Ecology, Evolution, and Behavior, University of MinnesotaSt. Paul, MN, USA
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21
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Bosak T, Schubotz F, de Santiago-Torio A, Kuehl JV, Carlson HK, Watson N, Daye M, Summons RE, Arkin AP, Deutschbauer AM. System-Wide Adaptations of Desulfovibrio alaskensis G20 to Phosphate-Limited Conditions. PLoS One 2016; 11:e0168719. [PMID: 28030630 PMCID: PMC5193443 DOI: 10.1371/journal.pone.0168719] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 12/04/2016] [Indexed: 12/13/2022] Open
Abstract
The prevalence of lipids devoid of phosphorus suggests that the availability of phosphorus limits microbial growth and activity in many anoxic, stratified environments. To better understand the response of anaerobic bacteria to phosphate limitation and starvation, this study combines microscopic and lipid analyses with the measurements of fitness of pooled barcoded transposon mutants of the model sulfate reducing bacterium Desulfovibrio alaskensis G20. Phosphate-limited G20 has lower growth rates and replaces more than 90% of its membrane phospholipids by a mixture of monoglycosyl diacylglycerol (MGDG), glycuronic acid diacylglycerol (GADG) and ornithine lipids, lacks polyphosphate granules, and synthesizes other cellular inclusions. Analyses of pooled and individual mutants reveal the importance of the high-affinity phosphate transport system (the Pst system), PhoR, and glycolipid and ornithine lipid synthases during phosphate limitation. The phosphate-dependent synthesis of MGDG in G20 and the widespread occurrence of the MGDG/GADG synthase among sulfate reducing ∂-Proteobacteria implicate these microbes in the production of abundant MGDG in anaerobic environments where the concentrations of phosphate are lower than 10 μM. Numerous predicted changes in the composition of the cell envelope and systems involved in transport, maintenance of cytoplasmic redox potential, central metabolism and regulatory pathways also suggest an impact of phosphate limitation on the susceptibility of sulfate reducing bacteria to other anthropogenic or environmental stresses.
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Affiliation(s)
- Tanja Bosak
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | | | - Ana de Santiago-Torio
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Jennifer V Kuehl
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Hans K Carlson
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Nicki Watson
- W.M. Keck Microscopy Facility, The Whitehead Institute, Cambridge, Massachusetts, United States of America
| | - Mirna Daye
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Roger E Summons
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Adam P Arkin
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.,Department of Bioengineering, University of California, Berkeley, Berkeley, California, United States of America
| | - Adam M Deutschbauer
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
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22
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Kohler TJ, Van Horn DJ, Darling JP, Takacs-Vesbach CD, McKnight DM. Nutrient treatments alter microbial mat colonization in two glacial meltwater streams from the McMurdo Dry Valleys, Antarctica. FEMS Microbiol Ecol 2016; 92:fiw049. [PMID: 26940086 DOI: 10.1093/femsec/fiw049] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2016] [Indexed: 01/06/2023] Open
Abstract
Microbial mats are abundant in many alpine and polar aquatic ecosystems. With warmer temperatures, new hydrologic pathways are developing in these regions and increasing dissolved nutrient fluxes. In the McMurdo Dry Valleys, thermokarsting may release both nutrients and sediment, and has the potential to influence mats in glacial meltwater streams. To test the role of nutrient inputs on community structure, we created nutrient diffusing substrata (NDS) with agar enriched in N, P and N + P, with controls, and deployed them into two Dry Valley streams. We found N amendments (N and N + P) to have greater chlorophyll-a concentrations, total algal biovolume, more fine filamentous cyanobacteria and a higher proportion of live diatoms than other treatments. Furthermore, N treatments were substantially elevated in Bacteroidetes and the small diatom, Fistulifera pelliculosa. On the other hand, species richness was almost double in P and N + P treatments over others, and coccoid green algae and Proteobacteria were more abundant in both streams. Collectively, these data suggest that nutrients have the potential to stimulate growth and alter community structure in glacial meltwater stream microbial mats, and the recent erosion of permafrost and accelerated glacial melt will likely impact resident biota in polar lotic systems here and elsewhere.
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Affiliation(s)
- Tyler J Kohler
- Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Boulder, CO 80303, USA Faculty of Science, Department of Ecology, Charles University in Prague, Viničná 7, 12844 Prague 2, Prague, Czech Republic
| | - David J Van Horn
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Joshua P Darling
- Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Boulder, CO 80303, USA
| | | | - Diane M McKnight
- Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Boulder, CO 80303, USA
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23
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24
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Yao M, Elling FJ, Jones C, Nomosatryo S, Long CP, Crowe SA, Antoniewicz MR, Hinrichs KU, Maresca JA. Heterotrophic bacteria from an extremely phosphate-poor lake have conditionally reduced phosphorus demand and utilize diverse sources of phosphorus. Environ Microbiol 2016; 18:656-67. [PMID: 26415900 PMCID: PMC5872838 DOI: 10.1111/1462-2920.13063] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/17/2015] [Accepted: 09/20/2015] [Indexed: 11/29/2022]
Abstract
Heterotrophic Proteobacteria and Actinobacteria were isolated from Lake Matano, Indonesia, a stratified, ferruginous (iron-rich), ultra-oligotrophic lake with phosphate concentrations below 50 nM. Here, we describe the growth of eight strains of heterotrophic bacteria on a variety of soluble and insoluble sources of phosphorus. When transferred to medium without added phosphorus (P), the isolates grow slowly, their RNA content falls to as low as 1% of cellular dry weight, and 86-100% of the membrane lipids are replaced with amino- or glycolipids. Similar changes in lipid composition have been observed in marine photoautotrophs and soil heterotrophs, and similar flexibility in phosphorus sources has been demonstrated in marine and soil-dwelling heterotrophs. Our results demonstrate that heterotrophs isolated from this unusual environment alter their macromolecular composition, which allows the organisms to grow efficiently even in their extremely phosphorus-limited environment.
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Affiliation(s)
- Mengyin Yao
- Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716
| | - Felix J. Elling
- Organic Geochemistry Group, MARUM-Center for Marine Environmental Sciences, University of Bremen, 28334 Bremen, Germany
| | - CarriAyne Jones
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Sulung Nomosatryo
- Research Center for Limnology, Indonesian Institute of Sciences (LIPI), Cibinong, West Java, Indonesia 16911
| | - Christopher P. Long
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark DE 19716
| | - Sean A. Crowe
- Departments of Microbiology & Immunology and Earth, Ocean, and Atmosphere Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Maciek R. Antoniewicz
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark DE 19716
| | - Kai-Uwe Hinrichs
- Organic Geochemistry Group, MARUM-Center for Marine Environmental Sciences, University of Bremen, 28334 Bremen, Germany
| | - Julia A. Maresca
- Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716
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25
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Logue JB, Findlay SEG, Comte J. Editorial: Microbial Responses to Environmental Changes. Front Microbiol 2015; 6:1364. [PMID: 26696977 PMCID: PMC4667068 DOI: 10.3389/fmicb.2015.01364] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 11/17/2015] [Indexed: 12/03/2022] Open
Affiliation(s)
- Jürg B Logue
- Aquatic Ecology, Department of Biology, Lund University Lund, Sweden ; Science for Life Laboratory Stockholm, Sweden
| | | | - Jérôme Comte
- Département de Biologie, Centre d'études Nordiques - Takuvik and Institut de Biologie Intégrative et des Systèmes, Université Laval Québec, QC, Canada
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