Thermobacillus xylanilyticus gen. nov., sp nov., a new aerobic thermophilic xylan-degrading bacterium isolated from farm soil

An aerobic, thermophilic, xylanolytic, spore-forming bacterium, XETP (T = t ype strain; P = patent strain), has been isolated from farm soil situated u nderneath a manure heap in northern France. Strain XETP, which Stained nega tive in the Cram test, occurs as short rods which sometimes form chains. It s spores are ellipsoidal, central to subterminal and occur in swollen spora ngia. It grows at temperatures up to 63 degrees C and in the ph range 6.5-8 .5. When grown on glucose in optimal conditions, its doubling time! was fou nd to be 33 min. CO2 was observed to have a growth-stimulating effect at th e start of the culture. In addition to glucose, the isolate utilizes xylose , arabinose, mannose, cellobiose, galactose, maltose, sucrose, xylan and st arch. Growth is inhibited by 5% NaCl. The G+C content of strain XETP is 57. 5 mol%. The 16S rDNA sequence analysis indicated that strain XETP falls int o the radiation of the Bacillus-Lactobacillus-Streptococcus subdivision of the Cram-positive phylum. Its three closest phylogenetic relatives are 'Bac illus viscosus', Paenibacillus curdlanolyticus and Bacillus popilliae with identity values of 91.15, 90.94 and 90.92 %, respectively. The major cellul ar fatty acids are 14-methyl pentadecanoic acid (16:0 iso), hexadecanoic ac id (16:0) and 14-methyl hexadecanoic acid (17:0 anteiso). On the basis of 1 6S rRNA sequence and chemotaxonomic characteristics, the isolate is differe nt enough for it to be considered as a member of a new genus. It is therefo re proposed that this isolate represents a new genus and species: Thermobac illus xylanilyticus. Strain XETP, the type strain of Thermobacillus xylanil yticus, has been deposited in the CollectionNationale de Cultures Microbien nes (CNCM 1-1017) as a patent strain. An aerobic, thermophilic, xylanolytic . spore-forming bacterium, XETP (7 = type strain; P = patent strain.