Microbacterium xylanilyticum sp. nov. a xylanolitic bacterium able to solubilize phosphate isolated from sawdust of Ulmus nigra.

Raúl Rivas, Martha E. Trujillo, Manuel Sánchez, P.F. Mateos, E. Martínez-Molina and Encarna Velázquez

Departamento de Microbiología y Genética. Edificio Departamental. Campus Miguel de Unamuno. Universidad de Salamanca. SPAIN.

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A bacterial strain designated XIL02^T, isolated from sawdust of Ulmus nigra in Spain produced abundant xylanases. The microorganism is Gram positive, aerobic, rod-shaped and non-motile. Growth was observed with xylan or starch as the only carbon source. The strain did not present catalase or oxidase activity. Colonies on YED are circular convex, white, opaque and usually 1 to 3 mm in diameter within 7 days of growth at 28°C. Strain XIL02^T utilizes mannose, L-arabinose, rhamnose, maltose, xylan, carboxymethylcellulose and starch as carbon sources. By contrast, it does not grow in acetate or citrate as carbon sources. This strain actively produces xylanases, cellulases, caseinase, gelatinase, amylases, b-galactosidase. Aesculin is hydrolysed, reduces nitrate and produces acetoin (Voges-Proskauer medium). It does not produce arginine dehydrolase, ornitine decarboxilase, lysine decarboxilase, tryptophan deaminase, urease or indol. The complete 16S rDNA sequence of this microorganism was obtained and phylogenetic analysis based on the neighbour-joining method indicated that this bacterium belongs to the high G+C content Gram positive bacteria and that the most closely related was genus Microbacterium. The G+C DNA content determined was 76 mol %. According to the data obtained in this work, this bacterium belongs to a new genus and the name Xylanomicrobium xylanilyticum gen. nov. sp. nov. is proposed for the strain XIL02^T (LMG 20991 and CECT 5976).