The anaerobic monotrichous butyric acid-producing curved rod-shaped bacteria of the rumen.

During studies of bacteria isolated from rumen contents, several workers have encountered anaerobic, gram negative, butyric acid-producing curved rods (Hungate, 1950; Huhtanen and Gall, 1952; and Wilson, 1953). Bryant and Burkey (1953a) published brief descriptions of three groups of anaerobic, motile, curved rods. Further studies have shown that four fundamentally different kinds of bacteria were included in these groups. They include organisms producing large amounts of butyric acid from glucose; organisms producing large amounts of succinic acid from glucose; organisms that belong in the species Selenomonas ruminantium because of the characteristic morphology, arrangement of flagella, and habitat; and gram positive organisms that ferment glucose with the production of large amounts of ethanol and lactic, formic and acetic acids. The purpose of the present paper is to describe the characteristics and to name the butyric acidproducing organisms.