The Amino Acid-fermenting Clostridia

Abstract

Summary: Representative strains of 30 named species of clostridia were tested for their ability to grow in a semidefined medium containing either 1 % (w/v) glucose or 3 % (w/v) acid-hydrolysed casein as an energy source. Strains from 15 species were selected empirically as amino acid-fermenting types by comparing growth in the two media. After growth in 3 % casein hydrolysate medium the organisms were removed and their amino acid utilization determined by examining the culture supernatants. The organisms were then divided into four main groups. The characteristic features of each group are as follows: group I, the utilization of proline with the production of δ-amino valeric acid; group II, mainly arginine and/or glycine utilized; group III, the utilization of glutamic acid, serine and histidine; group IV, serine and threonine utilized. Possible implications of these findings for the taxonomy of clostridia are discussed.