Limits...
Co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture.

Zheng S, Zhang H, Li Y, Zhang H, Wang O, Zhang J, Liu F - Front Microbiol (2015)

Bottom Line: First, iron (III) reducers including Geobacteraceae were successfully enriched by 3-months successive culture on amorphous Fe(III) oxides as electron acceptor and acetate as electron donor.Remarkably, aggregates were successively formed in the enrichments after three transfers.The results revealed by RNA-based analysis demonstrate that the co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences Yantai, China ; Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences Yantai, China.

ABSTRACT
Methanosaeta harundinacea and Methanosarcina barkeri, known as classic acetoclastic methanogens, are capable of directly accepting electrons from Geobacter metallireducens for the reduction of carbon dioxide to methane, having been revealed as direct interspecies electron transfer (DIET) in the laboratory co-cultures. However, whether their co-occurrences are ubiquitous in the iron (III)-reducing environments and the other species of acetoclastic methanogens such as Methanosarcina mazei are capable of DIET are still unknown. Instead of initiating the co-cultures with pure cultures, two-step cultivation was employed to selectively enrich iron (III)-reducing microorganisms in a coastal gold mining river, Jiehe River, with rich iron content in the sediments. First, iron (III) reducers including Geobacteraceae were successfully enriched by 3-months successive culture on amorphous Fe(III) oxides as electron acceptor and acetate as electron donor. High-throughput Illumina sequencing, terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis based on 16S rRNA genes revealed that the enrichment cultures actively contained the bacteria belong to Geobacteraceae and Bacilli, exclusively dominated by the archaea belong to Methanosarcinaceae. Second, the enrichment cultures including methanogens and Geobacteraceae were transferred with ethanol as alternative electron donor. Remarkably, aggregates were successively formed in the enrichments after three transfers. The results revealed by RNA-based analysis demonstrate that the co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture. Furthermore, the aggregates, as close physical contact, formed in the enrichment culture, indicate that DIET could be a possible option for interspecies electron transfer in the aggregates.

No MeSH data available.


Neighbor-joining phylogenetic tree of representative bacterial (A) and archaeal (B) 16S rRNA gene clones generated from DNA and RNA extracted from in situ sediments and enrichment cultures. Numbers of T-RF lengths are shown in base pairs. An association with the sequence of the highest similarity in the database and GenBank accession number of reference sequence as indicated. The scale bars represents 5% (A) and 10% (B) sequence divergence, respectively. Methanocella paludicola and Acidovorax ebreus were selected as outgroups of bacterial (A) and archaeal (B) phylogenetic tree, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4562271&req=5

Figure 5: Neighbor-joining phylogenetic tree of representative bacterial (A) and archaeal (B) 16S rRNA gene clones generated from DNA and RNA extracted from in situ sediments and enrichment cultures. Numbers of T-RF lengths are shown in base pairs. An association with the sequence of the highest similarity in the database and GenBank accession number of reference sequence as indicated. The scale bars represents 5% (A) and 10% (B) sequence divergence, respectively. Methanocella paludicola and Acidovorax ebreus were selected as outgroups of bacterial (A) and archaeal (B) phylogenetic tree, respectively.

Mentions: In order to affiliate the detected T-RFs to phylogenetic bacterial groups, four clone libraries were generated using the samples. The phylogenetic affiliations of all bacterial clones analyzed were summarized in Table 2. The phylogenetic placement of selected representative clones was shown in Figure 5A.


Co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture.

Zheng S, Zhang H, Li Y, Zhang H, Wang O, Zhang J, Liu F - Front Microbiol (2015)

Neighbor-joining phylogenetic tree of representative bacterial (A) and archaeal (B) 16S rRNA gene clones generated from DNA and RNA extracted from in situ sediments and enrichment cultures. Numbers of T-RF lengths are shown in base pairs. An association with the sequence of the highest similarity in the database and GenBank accession number of reference sequence as indicated. The scale bars represents 5% (A) and 10% (B) sequence divergence, respectively. Methanocella paludicola and Acidovorax ebreus were selected as outgroups of bacterial (A) and archaeal (B) phylogenetic tree, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562271&req=5

Figure 5: Neighbor-joining phylogenetic tree of representative bacterial (A) and archaeal (B) 16S rRNA gene clones generated from DNA and RNA extracted from in situ sediments and enrichment cultures. Numbers of T-RF lengths are shown in base pairs. An association with the sequence of the highest similarity in the database and GenBank accession number of reference sequence as indicated. The scale bars represents 5% (A) and 10% (B) sequence divergence, respectively. Methanocella paludicola and Acidovorax ebreus were selected as outgroups of bacterial (A) and archaeal (B) phylogenetic tree, respectively.
Mentions: In order to affiliate the detected T-RFs to phylogenetic bacterial groups, four clone libraries were generated using the samples. The phylogenetic affiliations of all bacterial clones analyzed were summarized in Table 2. The phylogenetic placement of selected representative clones was shown in Figure 5A.

Bottom Line: First, iron (III) reducers including Geobacteraceae were successfully enriched by 3-months successive culture on amorphous Fe(III) oxides as electron acceptor and acetate as electron donor.Remarkably, aggregates were successively formed in the enrichments after three transfers.The results revealed by RNA-based analysis demonstrate that the co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences Yantai, China ; Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences Yantai, China.

ABSTRACT
Methanosaeta harundinacea and Methanosarcina barkeri, known as classic acetoclastic methanogens, are capable of directly accepting electrons from Geobacter metallireducens for the reduction of carbon dioxide to methane, having been revealed as direct interspecies electron transfer (DIET) in the laboratory co-cultures. However, whether their co-occurrences are ubiquitous in the iron (III)-reducing environments and the other species of acetoclastic methanogens such as Methanosarcina mazei are capable of DIET are still unknown. Instead of initiating the co-cultures with pure cultures, two-step cultivation was employed to selectively enrich iron (III)-reducing microorganisms in a coastal gold mining river, Jiehe River, with rich iron content in the sediments. First, iron (III) reducers including Geobacteraceae were successfully enriched by 3-months successive culture on amorphous Fe(III) oxides as electron acceptor and acetate as electron donor. High-throughput Illumina sequencing, terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis based on 16S rRNA genes revealed that the enrichment cultures actively contained the bacteria belong to Geobacteraceae and Bacilli, exclusively dominated by the archaea belong to Methanosarcinaceae. Second, the enrichment cultures including methanogens and Geobacteraceae were transferred with ethanol as alternative electron donor. Remarkably, aggregates were successively formed in the enrichments after three transfers. The results revealed by RNA-based analysis demonstrate that the co-occurrence of Methanosarcina mazei and Geobacteraceae in an iron (III)-reducing enrichment culture. Furthermore, the aggregates, as close physical contact, formed in the enrichment culture, indicate that DIET could be a possible option for interspecies electron transfer in the aggregates.

No MeSH data available.