Xylanimonas cellulosilytica gen. nov., sp. nov., a xylanolytic bacterium isolated from a decayed tree (Ulmus nigra).

Abstract

A bacterial strain, designated XIL07T, isolated from a decayed tree, Ulmus nigra, in Salamanca (Spain) produced abundant cellulases and xylanases. The micro-organism was Gram-positive, aerobic, coccoid and non-motile. Growth was observed on many carbohydrates, including cellulose and xylan as the sole carbon sources. No growth was observed with acetate, citrate, gluconate, inositol, malate or mannitol as carbon sources. The strain showed very weak catalase activity. HPLC analysis of menaquinones revealed two peaks: the main peak corresponded with MK-9(H4) and the smaller one with MK-8(H4). The major fatty acid found was anteiso-C15:0 (12-methyl tetradecanoic acid). Mycolic acids were absent. The polar lipids detected were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. Peptidoglycan type was A4alpha, L-Lys-D-Asp. The cell-wall sugars detected were galactose and rhamnose. The complete 16S rDNA sequence of strain XIL07T 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 closest related genera are Promicromonospora and Cellulosimicrobium. The DNA G + C content was 73 mol%. According to the data obtained in this work, this bacterium belongs to a new genus in the family Promicromonosporaceae and the name Xylanimonas cellulosilytica gen. nov., sp. nov. is proposed; the type strain is strain XIL07T (=LMG 20990T =CECT 5975T).