Microbispora Cellulosiformans Sp. Nov., a Novel Actinomycete with Cellulase Activity Isolated from Soil in the Cold Region

A novel cellulase-producing actinomycete strain Gxj-6, isolated from soil in the cold region (Heihe city, Heilongjiang province, the northernmost part of China), subjected to a taxonomic study using a polyphasic approach. In the neighbour-joining phylogenetic tree based on 16S rRNA gene sequences, strain Gxj-6 fell within the clade comprising the type strains of species of the genus Microbispora. 16S rRNA gene sequence similarity studies exhibited that species Gxj-6 was most closely related to Microbispora bryophytorum NEAU-TX2-2 (99.45%), Microbispora fusca NEAU-HEGS1-5 (99.41%), Microbispora camponoti 2C-HV3 (99.31%) and Microbispora rosea subsp. rosea JCM 3006 (98.68%). Organism Gxj-6 contained MK-9(H) as the predominant ubiquinone and C 10-methyl as the major fatty acid. The major polar lipids of culture Gxj-6 were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol mannoside, three unidentified phospholipids, two unidentified glycolipids and two unidentified lipids. The DNA G+C content of strain Gxj-6 was 71.25 mol%. The morphological and chemotaxonomic properties of the strain are also consistent with those members of the genus Microbispora. Combinated with the lower DNA-DNA relatedness values, phenotypic properties, physiology and biochemistry distinctiveness with other recognized species strains, revealed that strain Gxj-6 is separated from other phylogenetically closely species of the genus Microbispora. Therefore, strain Gxj-6 is considered to represent a novel species of the genus Microbispora, for which the name Microbispora cellulosiformans sp. nov. is proposed. The type strain is Gxj-6 (= CGMCC 4.7605 = DSM 109712).