Lactate dehydrogenase gene variability among predominant lactate utilizing ruminal bacteria

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Lactate dehydrogenase (LDH) is crucial for lactate metabolism in ruminal bacteria.
• Understanding LDH gene variability is key to characterizing these microorganisms.
• Megasphaera elsdenii and Selenomonas ruminantium are predominant lactate-utilizing bacteria in the rumen.

Purpose of the Study:

• To determine the inter- and intraspecies variability of the lactate dehydrogenase (ldh) gene.
• To compare ldh gene sequences among different strains of M. elsdenii and S. ruminantium.
• To investigate the evolutionary history and potential gene transfer of the ldh gene.

Main Methods:

• Obtained nearly complete nucleotide sequences of the ldh gene from three M. elsdenii and six S. ruminantium strains.
• Performed phylogenetic analyses to compare ldh gene sequences.
• Analyzed sequence differences, focusing on mutations at the codon's 3rd position.

Main Results:

• Limited variability was observed in the ldh gene sequences between M. elsdenii and S. ruminantium.
• Most observed differences were silent mutations in the 3rd position of codons.
• Intraspecies diversity of the ldh gene in S. ruminantium was higher than interspecies diversity between S. ruminantium and M. elsdenii.

Conclusions:

• The ldh gene exhibits low variability among the studied ruminal bacteria.
• The higher intraspecies diversity in S. ruminantium strongly suggests horizontal gene transfer as a mechanism for ldh gene acquisition.
• This finding provides insights into the genetic adaptability of ruminal bacteria.