Isolation and characterization of methanogens from rumen of Murrah buffalo

摘要

Methanogens were isolated from the rumen of Murrah buffaloes (Bubalus bubalis). These isolates (BRM-1, -2 and -3) were found to utilize CO₂ + H₂ mixture, formate and acetate as substrate, but failed to grow on ethanol and methanol. Their physiological analysis showed that they could tolerate NaCl and bile salts up to 1.0% but 2.0% bile salt inhibited their growth. Based on 16S rRNA/mcrA gene sequence analysis, the isolates showed their phylogenetic relation with genus Methanobrevibacter and Methanomicrobium. BRM-1 and -3 showed 100% similarity with Methanobrevibacter smithii, while BRM-2 showed 100% similarity with Methanomicrobium mobile. The mcrA protein-based phylogeny also showed similar results to the mcrA gene, suggesting no apparent difference in the phylogeny between DNA and amino acid sequences of these isolates.