Identification and enumeration of oleic acid and linoleic acid hydrating bacteria in the rumen of sheep and cows

The diversity and population densities of facultative anaerobic bacteria wi th the capacity to hydrate oleic acid and linoleic acid in the rumen of she ep and dairy cows were determined. The screening of representative colonies , from rumen fluid plated aerobically on a range of agar media, revealed th at sheep rumen fluid contained hydration-positive strains of Streptococcus, Staphylococcus, Enterococcus, Lactobacillus and Pediococcus, whereas cow r umen fluid contained hydration-positive strains of Streptococcus, Lactobaci llus and Staphylococcus. Mean counts of facultative anaerobic bacteria in s heep and cattle rumen were log(10) 7.29 and log(10) 6.40, respectively, and were independent of diet. Approximately 56% of facultative anaerobic bacte ria were able to hydrate oleic and/or linoleic acid in anaerobic broth cult ure. For both sheep and cows, the most numerous hydration-positive isolates were strains of Strep. bovis. The results, which are the first to show tha t pediococci have the capacity to hydrate unsaturated fatty acids, suggest that lactic acid bacteria are the major unsaturated fatty acid hydrating ba cteria in the rumen.