Isolation and Characterization of an Anaerobic, Cellulolytic Microorganism, Acetivibrio cellulolyticus gen. nov., sp. nov.

Abstract

A new genus of cellulolytic, gram-negative, nonsporeforming, anaerobic bacteria is described. The colonies produced by these bacteria on cellulose agar were round, clear, translucent, and cream-colored and had an undulate margin. Single cells of the bacterium were straight to slightly curved rods 0.5-0.8 .mu.m wide by 4-10 .mu.m long and were motile by means of a single flagellum located 1/3 of the distance from the end of the cell. Among the various substrates tested, only cellulose, cellobiose and salicin were able to support growth. The major fermentation products of cellobiose or cellulose degradation were acetic acid, H2 and CO2. The DNA base composition of the type species was 38 mol% guanine plus cytosine. The name ACETIVIBRIO is proposed for this new genus, which is placed in the family Bacteroidaceae. The type species, A. cellulolyticus sp. nov., is named on the basis of its cellulolytic activity. The type strain of A. cellulolyticus is CD2 (= NRC 2248).