SYNERGISTES-JONESII, GEN-NOV, SP-NOV - A RUMEN BACTERIUM THAT DEGRADES TOXIC PYRIDINEDIOLS

This study was conducted to identify and characterize rumen bacteria that are able to degrade the toxic compound, 3-hydroxy-4(1H)-pyridone (3,4 DHP), that is produced in the rumen from mimosine. Mimosine is a non-protein amino acid that is found in leaves and seeds of Leucaena leucocephala, a leguminous tree used as a forage crop for ruminants in the tropics, and degradation of 3,4 DHP by ruminal microbes is critical for protection of animals from leucaena toxicity. Microbes with this capacity are, however, not ubiquitous and microbial populations in the rumens of animals in some parts of the world are unable to metabolize 3,4 DHP. Four strains of obligately anaerobic, gram-negative, rod-shaped bacteria that degrade 3,4 DHP were isolated from rumen contents from a goat in Hawaii. The isolates do not ferment carbohydrates, but are able to use both 3,4 DHP and its isomer, 3-hydroxy-2(1H)-pyridone (2,3 DHP), as well as arginine and histidine as substrates for growth. Comparisons of the 16S rRNA sequence from one of these isolates with sequences from a widely diverse group of bacteria agree with other information indicating that these isolates do not fit into any existing taxon. Thus, we are hereby proposing a new genus and species designation, Synergistes jonesii, for these organisms.