Cellulosimicrobium composti sp. nov., a thermophilic bacterium isolated from compost

A Gram-stain-positive, yellow-pigmented, non-motile actinobacterial strain, designated as BIT-GX5^T, was isolated from a sesame husks compost collected in Beijing, PR China. This bacterium was found to be able to grow in the temperature range from 16 to 50 °C and had an optimal growth temperature at 45 °C. Its taxonomic position was analysed using a polyphasic approach. The 16S rRNA gene sequence (1482 bp) of strain BIT-GX5^T was most similar to Cellulosimicrobium funkei ATCC BAA-886^T (99.45%), Cellulosimicrobium cellulans LMG 16121^T (99.17%) and Cellulosimicrobium marinum RS-7-4^T (98.75%). The results of phylogenetic analyses, based on the 16S rRNA gene, concatenated sequences of five housekeeping genes (gyrB, rpoB, recA, atpD and trpB) and genome sequences, placed strain BIT-GX5^T in a separate lineage among the genus Cellulosimicrobium within the family Promicromonosporaceae. The major polar lipids of strain BIT-GX5^T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, aminophospholipid and aminolipid. The major isoprenoid quinone was MK-9(H₄), while the cell-wall sugars were galactose, rhamnose, glucose and mannose. The peptidoglycan type was A4α l-Lys-d-Ser-d-Asp. The major fatty acids were anteiso-C_15:0 and iso-C_15: 0, which were similar to other members in the genus Cellulosimicrobium. Results of in silico DNA-DNA hybridization and average nucleotide identity calculations plus physiological and biochemical tests exhibited the genotypic and phenotypic differentiation of strain BIT-GX5^T from the other members of the genus Cellulosimicrobium. Therefore, strain BIT-GX5^T is considered to represent a novel species within the genus Cellulosimicrobium, for which the name Cellulosimicrobium composti sp. nov. is proposed. The type strain is BIT-GX5^T (= CGMCC 1.17687^T = KCTC 49391^T).