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McNichol SM, Sanchez-Quete F, Loeb SK, Teske AP, Shah Walter SR, Mahmoudi N. Dynamics of carbon substrate competition among heterotrophic microorganisms. THE ISME JOURNAL 2024; 18:wrae018. [PMID: 38366177 PMCID: PMC10942773 DOI: 10.1093/ismejo/wrae018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 01/06/2024] [Accepted: 01/26/2024] [Indexed: 02/18/2024]
Abstract
Growing evidence suggests that interactions among heterotrophic microorganisms influence the efficiency and rate of organic matter turnover. These interactions are dynamic and shaped by the composition and availability of resources in their surrounding environment. Heterotrophic microorganisms inhabiting marine environments often encounter fluctuations in the quality and quantity of carbon inputs, ranging from simple sugars to large, complex compounds. Here, we experimentally tested how the chemical complexity of carbon substrates affects competition and growth dynamics between two heterotrophic marine isolates. We tracked cell density using species-specific polymerase chain reaction (PCR) assays and measured rates of microbial CO2 production along with associated isotopic signatures (13C and 14C) to quantify the impact of these interactions on organic matter remineralization. The observed cell densities revealed substrate-driven interactions: one species exhibited a competitive advantage and quickly outgrew the other when incubated with a labile compound whereas both species seemed to coexist harmoniously in the presence of more complex organic matter. Rates of CO2 respiration revealed that coincubation of these isolates enhanced organic matter turnover, sometimes by nearly 2-fold, compared to their incubation as mono-cultures. Isotopic signatures of respired CO2 indicated that coincubation resulted in a greater remineralization of macromolecular organic matter. These results demonstrate that simple substrates promote competition whereas high substrate complexity reduces competitiveness and promotes the partitioning of degradative activities into distinct niches, facilitating coordinated utilization of the carbon pool. Taken together, this study yields new insight into how the quality of organic matter plays a pivotal role in determining microbial interactions within marine environments.
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Affiliation(s)
- Samuel M McNichol
- Department of Earth and Planetary Sciences, McGill University, 3450 University St, Montréal, Quebec H3A 0E8, Canada
| | - Fernando Sanchez-Quete
- Department of Civil Engineering, McGill University, 817 Rue Sherbrooke Ouest, Montréal, Quebec H3A 0C3, Canada
| | - Stephanie K Loeb
- Department of Civil Engineering, McGill University, 817 Rue Sherbrooke Ouest, Montréal, Quebec H3A 0C3, Canada
| | - Andreas P Teske
- Department of Earth, Marine and Environmental Sciences, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Sunita R Shah Walter
- School of Marine Science and Policy, University of Delaware, 700 Pilottown Rd, Lewes, DE 19958, United States
| | - Nagissa Mahmoudi
- Department of Earth and Planetary Sciences, McGill University, 3450 University St, Montréal, Quebec H3A 0E8, Canada
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Mahmoudi N, Wilhelm RC. Can we manage microbial systems to enhance carbon storage? Environ Microbiol 2023; 25:3011-3018. [PMID: 37431673 DOI: 10.1111/1462-2920.16462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 06/26/2023] [Indexed: 07/12/2023]
Abstract
Climate change is an urgent environmental issue with wide-ranging impacts on ecosystems and society. Microbes are instrumental in maintaining the balance between carbon (C) accumulation and loss in the biosphere, actively regulating greenhouse gas fluxes from vast reservoirs of organic C stored in soils, sediments and oceans. Heterotrophic microbes exhibit varying capacities to access, degrade and metabolise organic C-leading to variations in remineralisation and turnover rates. The present challenge lies in effectively translating this accumulated knowledge into strategies that effectively steer the fate of organic C towards prolonged sequestration. In this article, we discuss three ecological scenarios that offer potential avenues for shaping C turnover rates in the environment. Specifically, we explore the promotion of slow-cycling microbial byproducts, the facilitation of higher carbon use efficiency, and the influence of biotic interactions. The ability to harness and control these processes relies on the integration of ecological principles and management practices, combined with advances in economically viable technologies to effectively manage microbial systems in the environment.
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Affiliation(s)
- Nagissa Mahmoudi
- Department of Earth and Planetary Sciences, McGill University, Montréal, Quebec, Canada
| | - Roland C Wilhelm
- Department of Agronomy, Lilly Hall of Life Sciences, Purdue University, West Lafayette, Indiana, USA
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Sutherland KM, Johnston DT, Hemingway JD, Wankel SD, Ward CP. Revised microbial and photochemical triple-oxygen isotope effects improve marine gross oxygen production estimates. PNAS NEXUS 2022; 1:pgac233. [PMID: 36712381 PMCID: PMC9802178 DOI: 10.1093/pnasnexus/pgac233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 10/08/2022] [Indexed: 11/05/2022]
Abstract
The biogeochemical fluxes that cycle oxygen (O2) play a critical role in regulating Earth's climate and habitability. Triple-oxygen isotope (TOI) compositions of marine dissolved O2 are considered a robust tool for tracing oxygen cycling and quantifying gross photosynthetic O2 production. This method assumes that photosynthesis, microbial respiration, and gas exchange with the atmosphere are the primary influences on dissolved O2 content, and that they have predictable, fixed isotope effects. Despite its widespread use, there are major elements of this approach that remain uncharacterized, including the TOI dynamics of respiration by marine heterotrophic bacteria and abiotic O2 sinks such as the photochemical oxidation of dissolved organic carbon (DOC). Here, we report the TOI fractionation for O2 utilization by two model marine heterotrophs and by abiotic photo-oxidation of representative terrestrial and coastal marine DOC. We demonstrate that TOI slopes associated with these processes span a significant range of the mass-dependent domain (λ = 0.499 to 0.521). A sensitivity analysis reveals that even under moderate productivity and photo-oxidation scenarios, true gross oxygen production may deviate from previous estimates by more than 20% in either direction. By considering a broader suite of oxygen cycle reactions, our findings challenge current gross oxygen production estimates and highlight several paths forward to better understanding the marine oxygen and carbon cycles.
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Affiliation(s)
| | - David T Johnston
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Jordon D Hemingway
- ETH Zürich, Geological Institute, Department of Earth Sciences, Zürich 8092, Switzerland
| | - Scott D Wankel
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
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Li B, Feng M, Chen X, Wang Y, Shen Y, Wu QL. Abundant sediment organic matter potentially facilitates chemical iron reduction and surface water blackness in a Chinese deep lake. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 272:116002. [PMID: 33246758 DOI: 10.1016/j.envpol.2020.116002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/21/2020] [Accepted: 11/03/2020] [Indexed: 06/12/2023]
Abstract
Black bloom has become an increasingly severe environmental and ecological problem in lots of lakes. Ferrous monosulfide (FeS), which is closely related to chemical iron reduction (CIR), is considered the major cause for black water in shallow lakes, but few studies focus on the effect of organic matters (OM) content on iron and sulfate reduction and its contribution to the black bloom in deep lakes. Here, in Lake Fuxian, a Chinese deep lake which has also suffered from black bloom, FeS was identified responsible for the surface water blackness by using multiple microscopy and element analyses. Dissolved oxygen (DO) penetrated 1.6-4.2 mm in all sediment sites, further indicating FeS formed in the sediments instead of the permanently oxic water column. Geochemical characteristics revealed by diffusive gradients in thin films (DGT) showed that DGT-Fe2+ concentration was 57.6-1919.4 times higher than the DGT-S2- concentration and both were positively correlated with DGT-PO43-. Combining DGT profiles and anaerobic OM remineralization rate according to bag incubation, iron reduction is more effective than sulfate reduction although the two processes coexisted. Moreover, correlation of DGT-Fe2+ and DGT-PO43- was better than that of DGT-PO43- and DGT-S2- at OM-depleted sites but opposite at OM-rich sites. In addition, total organic carbon (TOC) was significantly positively related to acid volatile sulfide (AVS). We therefore conclude that abundant OM potentially exacerbate chemical iron reduction and further lead to surface water blackness. Our study revealed the mechanisms behind the black bloom and gives credence to the management strategy of reducing OM loading to protect water quality in deep lakes.
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Affiliation(s)
- Biao Li
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Muhua Feng
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
| | - Xiangchao Chen
- Shanghai Tingying Environmental Technology Co., Ltd, Shanghai, 201707, China
| | - Yarui Wang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Yue Shen
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Qinglong L Wu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China; Sino-Danish Centre for Education and Research, University of Chinese Academy of Sciences, Beijing, 100039, China
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