The inter- and intraspecies variability of lactate dehydrogenase (ldh) gene was determined among the predominant ruminal lactate utilizing bacteria. Nearly complete nucleotide sequences of ldh gene, encoding NAD-dependent lactate dehydrogenase of three Megasphaera elsdenii and six Selenomonas ruminantium strains, were obtained and compared. Phylogenetic analyses revealed a limited variability between the ldh sequences studied. The majority of differences observed were silent mutations at the 3rd position of codons. Surprisingly, the intraspecies diversity of the ldh gene among S. ruminantium isolates was higher than the interspecies level between S. ruminantium and M. elsdenii, which strongly suggests the possibility of acquisition of this gene by horizontal gene transfer.

• MeSH
• Rumen microbiology   MeSH
• Bacterial Proteins genetics   MeSH
• Point Mutation MeSH
• DNA, Bacterial chemistry   genetics   MeSH
• Phylogeny MeSH
• Genetic Variation * MeSH
• Lactic Acid metabolism   MeSH
• L-Lactate Dehydrogenase genetics   MeSH
• Megasphaera enzymology   genetics   isolation & purification   metabolism   MeSH
• Molecular Sequence Data MeSH
• Sequence Analysis, DNA MeSH
• Sequence Homology MeSH
• Selenomonas enzymology   genetics   isolation & purification   metabolism   MeSH
• Cluster Analysis MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Bacterial Proteins MeSH
• DNA, Bacterial MeSH
• Lactic Acid MeSH
• L-Lactate Dehydrogenase MeSH

Inhibition of methanogenesis in ruminal cultures was attempted by hindering thiamine availability through its degradation by 'polyphenols' and competition for active sites on enzymes and transporters using thiamine structural analogs. Effects on fermentation were small and not consistently reversed by adding thiamine. Lack of major effects of the compounds evaluated could be due to intracellular synthesis of thiamine covering most requirements.

• MeSH
• Rumen metabolism   microbiology   MeSH
• Fermentation MeSH
• Methane antagonists & inhibitors   MeSH
• Cattle MeSH
• Thiamine antagonists & inhibitors   MeSH
• Animals MeSH
• Check Tag
• Cattle MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Methane MeSH
• Thiamine MeSH