Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/1999
Publication Date: N/A
Interpretive Summary: A bacterium capable of metabolizing naturally occurring nitrotoxins that occur in plants was isolated from the bovine rumen. This bacterium's use of nitrotoxins allows ruminants to consume forage that would otherwise be toxic to the animal. This bacterium does not fit into any recognized genus, so a new name, Denitrobacterium detoxificans, has been proposed. Discovery of this microbe furthers our understanding of how the rumen and its microbes work. It also provides cattle and sheep producers information on how to adapt their animals to nitrotoxin-containing forages.
Technical Abstract: We describe a new group of anaerobic gram-positive bacteria isolated from the bovine rumen. Of 4 strains characterized, all obtained energy for growth via anaerobic respiration processes, oxidizing hydrogen, formate or lactate for the reduction of various oxidized nitrogen compounds. Trimethyl-amine oxide and dimethyl sulfoxide are also used as electron acceptors by all 4 strains. All 4 strains possess the capacity to metabolize nitropropanol and nitropropionic acid, toxins found in many forages consumed by ruminants, and thus may provide the host a measure of protection against intoxication. Only one strain, NPOH1, was found to reduce inorganic nitrate. None of the 4 strains were able to obtain energy for growth via fermentation of a variety of substrates. Genotypically, all 4 strains were closely related, sharing greater than 99% 16S rRNA gene sequence homology. The closest match found between the 16S rRNA gene sequence of all 4 strains to sequences available in GenBank was that of Coriobacterium glomerans (86% sequence homology), an anaerobe within the Actinomyces line of descent, but the latter was phenotypically dissimilar. To accommodate these ruminal bacteria we propose the creation of a new genus and species, Denitrobacterium detoxificans.