Identification and cultivation of anaerobic, syntrophic long-chain fatty acid-degrading microbes from mesophilic and thermophilic methanogenic sludges

Masashi Hatamoto, Hiroyuki Imachi, Akiyoshi Ohashi, Hideki Harada

Research output: Contribution to journalArticlepeer-review

77 Citations (Scopus)

Abstract

We investigated long-chain fatty acid (LCFA)-degrading anaerobic microbes by enrichment, isolation, and RNA-based stable isotope probing (SIP). Primary enrichment cultures were made with each of four LCFA substrates (palmitate, stearate, oleate, or linoleate, as the sole energy source) at 55°C or 37°C with two sources of anaerobic granular sludge as the inoculum. After several transfers, we obtained seven stable enrichment cultures in which LCFAs were converted to methane. The bacterial populations in these cultures were then subjected to 16S rRNA gene-based cloning, in situ hybridization, and RNA-SIP. In five of seven enrichment cultures, the predominant bacteria were affiliated with the family Syntrophomonadaceae. The other two enrichment cultures contained different bacterial populations in which the majority of members belonged to the phylum Firmicutes and the class Deltaproteobacteria. After several attempts to isolate these dominant bacteria, strain MPA, belonging to the family Syntrophomonadaceae, and strain TOL, affiliated with the phylum Firmicutes, were successfully isolated. Strain MPA converts palmitate to acetate and methane in syntrophic association with Methanospirillum hungatei. Even though strain TOL assimilated [13C] palmitate in the original enrichment culture, strain TOL has not shown the ability to degrade LCFAs after isolation. These results suggest that microbes involved in the degradation of LCFAs under methanogenic conditions might not belong only to the family Syntrophomonadaceae, as most anaerobic LCFA-degrading microbes do, but may also be found in phylogenetically diverse bacterial groups.

Original languageEnglish
Pages (from-to)1332-1340
Number of pages9
JournalApplied and environmental microbiology
Volume73
Issue number4
DOIs
Publication statusPublished - 2007 Feb

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Fingerprint Dive into the research topics of 'Identification and cultivation of anaerobic, syntrophic long-chain fatty acid-degrading microbes from mesophilic and thermophilic methanogenic sludges'. Together they form a unique fingerprint.

Cite this