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Analysis of microbial communities in the oil reservoir subjected to CO2-flooding by using functional genes as molecular biomarkers for microbial CO2 sequestration.

Liu JF, Sun XB, Yang GC, Mbadinga SM, Gu JD, Mu BZ - Front Microbiol (2015)

Bottom Line: As a comparison, these functional genes in the production water samples from oil reservoir only experienced water-flooding in areas of the same oil bearing bed were also analyzed.It showed that these functional genes were all of rich diversity in these samples, and the functional microbial communities and their diversity were strongly affected by a long-term exposure to injected CO2.More interestingly, microorganisms affiliated with members of the genera Methanothemobacter, Acetobacterium, and Halothiobacillus as well as hydrogen producers in CO2 injected area either increased or remained unchanged in relative abundance compared to that in water-flooded area, which implied that these microorganisms could adapt to CO2 injection and, if so, demonstrated the potential for microbial fixation and conversion of CO2 into methane in subsurface oil reservoirs.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology Shanghai, China.

ABSTRACT
Sequestration of CO2 in oil reservoirs is considered to be one of the feasible options for mitigating atmospheric CO2 building up and also for the in situ potential bioconversion of stored CO2 to methane. However, the information on these functional microbial communities and the impact of CO2 storage on them is hardly available. In this paper a comprehensive molecular survey was performed on microbial communities in production water samples from oil reservoirs experienced CO2-flooding by analysis of functional genes involved in the process, including cbbM, cbbL, fthfs, [FeFe]-hydrogenase, and mcrA. As a comparison, these functional genes in the production water samples from oil reservoir only experienced water-flooding in areas of the same oil bearing bed were also analyzed. It showed that these functional genes were all of rich diversity in these samples, and the functional microbial communities and their diversity were strongly affected by a long-term exposure to injected CO2. More interestingly, microorganisms affiliated with members of the genera Methanothemobacter, Acetobacterium, and Halothiobacillus as well as hydrogen producers in CO2 injected area either increased or remained unchanged in relative abundance compared to that in water-flooded area, which implied that these microorganisms could adapt to CO2 injection and, if so, demonstrated the potential for microbial fixation and conversion of CO2 into methane in subsurface oil reservoirs.

No MeSH data available.


Related in: MedlinePlus

Genes and pathways for CO2 fixation and bioconversion into CH4.
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Figure 1: Genes and pathways for CO2 fixation and bioconversion into CH4.

Mentions: Petroleum reservoirs are known to harbor diverse microorganisms including bacteria such as Proteobacteria, Firmicutes, Actinobacteria, and Chloroflexi and archaea such as methanogens and Archaeoglobales mentioned above (Magot et al., 2000; Li et al., 2010, 2011; Wang et al., 2011; Mbadinga et al., 2012) and they are expected to fix and/or convert CO2 into CH4 more effectively. To investigate whether oil reservoirs have the potential of CO2 biofixation and bioconversion of CO2 into CH4, and to have a better knowledge on microorganisms involved in this process and the impact of long-term CO2 exposure on them, studies from a viewpoint of functional genes are necessary. Functional genes involved in CO2 fixation and conversion into CH4 have been shown to be valuable functional biomarkers for detecting the microbial communities both in environments and enrichment cultures. The genes cbbL and cbbM respectively encoding the key enzymes ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) form I and II of the CBB cycle for CO2 fixation have been used to study microbial communities from hydrothermal vents of the Logatchev field (Hugler et al., 2010). The gene fthfs encoding formyltetrahydrofolate synthetase, a key enzyme in the reductive acetyl-CoA pathway, has been used to investigate the diversity of homoacetogenic bacteria in thermophilic and mesophilic anaerobic sludge (Ryan et al., 2008). Methyl-Coenzyme M reductase (mcr) is vital for CH4 formation, and the α-subunit of MCR (mcrA gene) is commonly used in the detection of specific groups of methanogenic communities (Juottonen et al., 2006). In addition, H2 should be supplied in the process of CO2 conversion into CH4. H2 can be produced by H2-producing prokaryotes which are polyphyletic. [Fe-Fe]-hydrogenases are known to catalyze H2 production in fermentative microorganisms, and thus gene encoding for [Fe-Fe]-hydrogenases represent a good marker gene for the detection of H2-producing anaerobes (Schmidt et al., 2010). These valuable functional biomarkers involved in CO2 fixation and conversion into CH4 are shown in Figure 1.


Analysis of microbial communities in the oil reservoir subjected to CO2-flooding by using functional genes as molecular biomarkers for microbial CO2 sequestration.

Liu JF, Sun XB, Yang GC, Mbadinga SM, Gu JD, Mu BZ - Front Microbiol (2015)

Genes and pathways for CO2 fixation and bioconversion into CH4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4379918&req=5

Figure 1: Genes and pathways for CO2 fixation and bioconversion into CH4.
Mentions: Petroleum reservoirs are known to harbor diverse microorganisms including bacteria such as Proteobacteria, Firmicutes, Actinobacteria, and Chloroflexi and archaea such as methanogens and Archaeoglobales mentioned above (Magot et al., 2000; Li et al., 2010, 2011; Wang et al., 2011; Mbadinga et al., 2012) and they are expected to fix and/or convert CO2 into CH4 more effectively. To investigate whether oil reservoirs have the potential of CO2 biofixation and bioconversion of CO2 into CH4, and to have a better knowledge on microorganisms involved in this process and the impact of long-term CO2 exposure on them, studies from a viewpoint of functional genes are necessary. Functional genes involved in CO2 fixation and conversion into CH4 have been shown to be valuable functional biomarkers for detecting the microbial communities both in environments and enrichment cultures. The genes cbbL and cbbM respectively encoding the key enzymes ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) form I and II of the CBB cycle for CO2 fixation have been used to study microbial communities from hydrothermal vents of the Logatchev field (Hugler et al., 2010). The gene fthfs encoding formyltetrahydrofolate synthetase, a key enzyme in the reductive acetyl-CoA pathway, has been used to investigate the diversity of homoacetogenic bacteria in thermophilic and mesophilic anaerobic sludge (Ryan et al., 2008). Methyl-Coenzyme M reductase (mcr) is vital for CH4 formation, and the α-subunit of MCR (mcrA gene) is commonly used in the detection of specific groups of methanogenic communities (Juottonen et al., 2006). In addition, H2 should be supplied in the process of CO2 conversion into CH4. H2 can be produced by H2-producing prokaryotes which are polyphyletic. [Fe-Fe]-hydrogenases are known to catalyze H2 production in fermentative microorganisms, and thus gene encoding for [Fe-Fe]-hydrogenases represent a good marker gene for the detection of H2-producing anaerobes (Schmidt et al., 2010). These valuable functional biomarkers involved in CO2 fixation and conversion into CH4 are shown in Figure 1.

Bottom Line: As a comparison, these functional genes in the production water samples from oil reservoir only experienced water-flooding in areas of the same oil bearing bed were also analyzed.It showed that these functional genes were all of rich diversity in these samples, and the functional microbial communities and their diversity were strongly affected by a long-term exposure to injected CO2.More interestingly, microorganisms affiliated with members of the genera Methanothemobacter, Acetobacterium, and Halothiobacillus as well as hydrogen producers in CO2 injected area either increased or remained unchanged in relative abundance compared to that in water-flooded area, which implied that these microorganisms could adapt to CO2 injection and, if so, demonstrated the potential for microbial fixation and conversion of CO2 into methane in subsurface oil reservoirs.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology Shanghai, China.

ABSTRACT
Sequestration of CO2 in oil reservoirs is considered to be one of the feasible options for mitigating atmospheric CO2 building up and also for the in situ potential bioconversion of stored CO2 to methane. However, the information on these functional microbial communities and the impact of CO2 storage on them is hardly available. In this paper a comprehensive molecular survey was performed on microbial communities in production water samples from oil reservoirs experienced CO2-flooding by analysis of functional genes involved in the process, including cbbM, cbbL, fthfs, [FeFe]-hydrogenase, and mcrA. As a comparison, these functional genes in the production water samples from oil reservoir only experienced water-flooding in areas of the same oil bearing bed were also analyzed. It showed that these functional genes were all of rich diversity in these samples, and the functional microbial communities and their diversity were strongly affected by a long-term exposure to injected CO2. More interestingly, microorganisms affiliated with members of the genera Methanothemobacter, Acetobacterium, and Halothiobacillus as well as hydrogen producers in CO2 injected area either increased or remained unchanged in relative abundance compared to that in water-flooded area, which implied that these microorganisms could adapt to CO2 injection and, if so, demonstrated the potential for microbial fixation and conversion of CO2 into methane in subsurface oil reservoirs.

No MeSH data available.


Related in: MedlinePlus