ISOLATION AND CHARACTERIZATION OF A NEW HYDROGEN-UTILIZING BACTERIUM FROM THE RUMEN

A new H-2/CO2-utilizing acetogenic bacterium was isolated from the rum en of a mature deer. This is the first report of a spore-forming Gram- negative bacterial species from the rumen. The organism was a strictly anaerobic, motile rod and was able to grow autotrophically on hydroge n and carbon dioxide. Acetate was the major product detected. Glucose, fructose and lactate were also fermented heterotrophically. The optim um pH for growth was 7.0-7.5, and the optimum temperature was 37-42 de grees C. Yeast extract was required for growth and rumen fluid was hig hly stimulatory. The DNA base ratio was 52.9 +/- 0.5 mol% G + C. On th e basis of these characteristics and fermentation products, the isolat e was considered to be different from acetogenic bacteria described pr eviously.