Jump to content

User:Envmicro22/Syntrophy

From Wikipedia, the free encyclopedia

Introduction

[edit]

In biology, syntrophy, synthrophy, or cross-feeding (from Greek syn meaning together, trophe meaning nourishment) is the phenomenon of one species feeding on the metabolic products of another species to cope up with the energy limitations by electron transfer. In this type of biological interaction, metabolite transfer happens between two or more metabolically diverse microbial species that lives in close proximity to each other. The growth of one partner depends on the nutrients, growth factors, or substrates provided by the other partner. Thus, syntrophism can be considered as an obligatory interdependency and a mutualistic metabolism between two different bacterial species

Microbial syntrophy

[edit]

Syntrophy is often used synonymously for mutualistic symbiosis especially between at least two different bacterial species. Syntrophy differs from symbiosis in a way that syntrophic relationship is primarily based on closely linked metabolic interactions to maintain thermodynamically favorable lifestyle in a given environment[1][2][3]. Syntrophy plays an important role in a large number of microbial processes especially in oxygen limited environments, methanogenic environments and anaerobic systems[2][4]. In anoxic or methanogenic environments such as wetlands, swamps, paddy fields, landfills, digestive tract of ruminants, and anerobic digesters syntrophy is employed to overcome the energy constraints as the reactions in these environments proceed close to thermodynamic equilibrium[5][4][6].

Mechanism of microbial syntrophy

[edit]

The main mechanism of syntrophy is removing the metabolic end products of one species so as to create an energetically favorable environment for another species[6]. This obligate metabolic cooperation is required to facilitate the degradation of complex organic substrates under anaerobic conditions. Complex organic compounds such as ethanol, propionate, butyrate, and lactate cannot be directly used as substrates for methanogenesis by methanogens. On the other hand, fermentation of these organic compounds cannot occur in fermenting microorganisms unless the hydrogen concentration is reduced to a low level by the methanogens. The key mechanism that ensures the success of syntrophy is interspecies electron transfer[7]. The interspecies electron transfer can be carried out via three ways: interspecies hydrogen transfer, interspecies formate transfer and interspecies direct electron transfer[7][8]. Reverse electron transport is prominent in syntrophic metabolism.

The metabolic reactions and the energy involved for syntrophic degradation with H2 consumption[9]:

An example of syntrophic mechanism in a co-culture which has an Organism S and organism M.o.H which involves the oxidization od ethanol into acetate and methane mediated by interspecies hydrogen transfer. Individuals of organism S are observed as obligate anaerobic bacteria that use ethanol as an electron donor, whereas M.o.H (are methanogens that oxidize hydrogen gas to produce methane[9].

Organism S: 2 Ethanol + 2 H2O → 2 Acetate− + 2 H+ + 4 H2 (ΔG°' = +9.6 kJ per reaction)

Strain M.o.H.: 4 H2 + CO2 → Methane + 2 H2O (ΔG°' = -131 kJ per reaction)

Co-culture:2 Ethanol + CO2 → 2 Acetate− + 2 H+ + Methane (ΔG°' = -113 kJ per reaction)

The oxidation of ethanol by organism S was made possible by consuming the hydrogen produced by organism S by the methanogen M.o.H by turning the positive Gibbs free energy into negative Gibbs free energy. This situation favors growth of organism S and also provides energy for methanogens by consuming hydrogen. Down the line, acetate accumulation is also prevented by similar syntrophic relationship[9]. Syntrophic degradation of substrates like butyrate and benzoate can also happen without hydrogen consumption[6].

An example of propionate and butyrate degradation with interspecies formate transfer carried out by the mutual system of Syntrophomonas wolfei and Methanobacterium formicicum[7]:

Propionate＋2H2O＋2CO2 → Acetate- ＋3Formate- ＋3H+ (ΔG°'=＋65.3 kJ/mol)

Butyrate＋2H2O＋2CO2 → 2Acetate- ＋3Formate- ＋3H+ ΔG°'=＋38.5 kJ/mol)

Direct interspecies electron transfer (DIET) which involves electron transfer without any electron carrier such as H2 or formate was reported in the co-culture system of Geobacter mettalireducens and Methanosaeto or Methanosarcina[7][10]

Examples of microbial syntrophy

[edit]

Biodegradation of pollutants

[edit]

Syntrophic microbial food webs play an integral role in bioremediation especially in environments contaminated with crude oil and petrol. Environmental contamination with oil is of high ecological importance and can be effectively mediated through syntrophic degradation by complete mineralization of alkane, aliphatic and hydrocarbon chains[11][12]

Degradation of amino acids

Amino acid fermenting anaerobes such as Clostridium species, Peptostreptococcus asacchaarolyticus, Acidaminococcus fermentans were known to breakdown amino acids like glutamate with the help of hydrogen scavenging methanogenic partners without going through the usual Stickland fermentation pathway[4][13]

Anaerobic digestion

Effective syntrophic cooperation between propionate oxidizing bacteria, acetate oxidizing bacteria and H2/acetate consuming methanogens is necessary to successfully carryout anaerobic digestion to produce biomethane[14][15][9]

Examples of syntrophic organisms

[edit]


References

[edit]
  1. ^ Sieber, Jessica R.; McInerney, Michael J.; Gunsalus, Robert P. (2012). "Genomic insights into syntrophy: the paradigm for anaerobic metabolic cooperation". Annual Review of Microbiology. 66: 429–452. doi:10.1146/annurev-micro-090110-102844. ISSN 1545-3251. PMID 22803797.
  2. ^ a b "Syntrophy in anaerobic global carbon cycles". Current Opinion in Biotechnology. 20 (6): 623–632. 2009-12-01. doi:10.1016/j.copbio.2009.10.001. ISSN 0958-1669.
  3. ^ McInerney, Michael J (May 1, 2007). "The genome of Syntrophus aciditrophicus: Life at the thermodynamic limit of microbial growth". PNAS. 104 (18).
  4. ^ a b c d (Endo)symbiotic Methanogenic Archaea. doi:10.1007/978-3-642-13615-3.pdf.
  5. ^ E.L. Morris, Brandon; Henneberger, Ruth; Huber, Harald; Moissl-Eichinger, Christine. "Microbial syntrophy: interaction for the common good". FEMS Microbiology Reviews. 37 (3): 384–406.
  6. ^ a b c d Jackson, Bradley E; McInerney, Michael J (24 January 2002). "Anaerobic microbial metabolism can proceed close to thermodynamic limits". Nature.
  7. ^ a b c d Zhang, Mingyuan; Zang, Lihua (2019). "A review if interspecies electron transfer in anaerobic digestion". IOP conf. ser: Earth Environ.
  8. ^ Rotaru, Amelia-Elena (2012). "Interspecies Electron Transfer via Hydrogen and Formate Rather than Direct Electrical Connections in Cocultures of Pelobacter carbinolicus and Geobacter sulfurreducens". Applied and Environmental Microbiology.
  9. ^ a b c d Zhang, Yao; Li, Chunxing; Yuan, Zengwei; Wang, Ruming; Angelidaki, Irini; Zhu, Gefu (2023-01-15). "Syntrophy mechanism, microbial population, and process optimization for volatile fatty acids metabolism in anaerobic digestion". Chemical Engineering Journal. 452: 139137. doi:10.1016/j.cej.2022.139137. ISSN 1385-8947.
  10. ^ "Direct Interspecies Electron Transfer - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-11-09.
  11. ^ Callaghan, A V (January 2012). "The genome sequence of Desulfatibacillum alkenivorans AK-01: a blueprint for anaerobic alkane oxidation". Environmental Microbiology.
  12. ^ Ferry, J. G.; Wolfe, R. S. (1976-02-01). "Anaerobic degradation of benzoate to methane by a microbial consortium". Archives of Microbiology. 107 (1): 33–40. doi:10.1007/BF00427864. ISSN 1432-072X.
  13. ^ Zindel, U.; Freudenberg, W.; Rieth, M.; Andreesen, J. R.; Schnell, J.; Widdel, F. (1988-07-01). "Eubacterium acidaminophilum sp. nov., a versatile amino acid-degrading anaerobe producing or utilizing H2 or formate". Archives of Microbiology. 150 (3): 254–266. doi:10.1007/BF00407789. ISSN 1432-072X.
  14. ^ Kamagata, Yoichi (2015-03-15), "Syntrophy in Anaerobic Digestion", Anaerobic Biotechnology, IMPERIAL COLLEGE PRESS, pp. 13–30, doi:10.1142/9781783267910_0002, ISBN 978-1-78326-790-3, retrieved 2022-11-11
  15. ^ Yue, Yanan; Wang, Junyu; Wu, Xiayuan; Zhang, Jianfeng; Chen, Zhongbing; Kang, Xuejing; Lv, Zuopeng (2021-04-01). "The fate of anaerobic syntrophy in anaerobic digestion facing propionate and acetate accumulation". Waste Management. 124: 128–135. doi:10.1016/j.wasman.2021.01.038. ISSN 0956-053X.
  16. ^ McInerney, M J (April 1981). "Syntrophomonas wolfei gen. nov. sp. nov., an Anaerobic, Syntrophic, Fatty Acid-Oxidizing Bacterium". Applied and Environmental microbiology. 41 (4): 1029–1039.
  17. ^ a b Schink, Bernhard; Stams, Alfons J. M. (2013), Rosenberg, Eugene; DeLong, Edward F.; Lory, Stephen; Stackebrandt, Erko (eds.), "Syntrophism Among Prokaryotes", The Prokaryotes: Prokaryotic Communities and Ecophysiology, Berlin, Heidelberg: Springer, pp. 471–493, doi:10.1007/978-3-642-30123-0_59, ISBN 978-3-642-30123-0, retrieved 2022-10-26
Retrieved from "https://en.wikipedia.org/w/index.php?title=User:Envmicro22/Syntrophy&oldid=1121587636"