A hydrogen sulphide producing Gram-negative rod from water.

The biochemical properties of a hydrogen sulphide-producing Gram-negative rod, provisionally designated HG group, were compared with those of the known H2S-producing and H2S-negative Enterobacteriaceae and related organisms. Sixty-four tests were used as a basis for numerical identification. All these tests demonstrated a distinctness of the HG group from other members of Enterobacteriaceae and related organisms. Results of numerical identification are discussed. According to the guanine-plus-cytosine molar content in DNA the bacterium could belong to the tribe Escherichiae of the family Enterobacteriaceae. Plasmids of different molecular size or linear fragments of DNA were found in 17 of 19 strains which indicates that the H2S production is not in correlation with the occurrence of a plasmid of definite size. So far, the only habitat of the HG group had been water, and it seems to be no rarity. Among 28 HG strains a single isolate HG16 was found which differs from HG group in biochemical properties. The distinctness of this single isolate has been confirmed also by numerical identification. Note: On the basis of DNA-DNA hybridization performed by Dr. P.A.D. Grimont and coworkers the HG group has been established as a new genus and a single species. The authors accordingly propose for the group the generic name Budvicia and the specific epithet aquatica.