Sphingobacterium athyrii sp. nov., a cellulose- and xylan-degrading bacterium isolated from a decaying fern (Athyrium wallichianum Ching)

Assessment of the bacterial diversity associated with a decaying fern, Athyrium wallichianum Ching, revealed the presence of a novel bacterial strain named M46(T). It was Gram-stain-negative, rod-shaped, non-motile and aerobic with cellulose and xylan degradation abilities. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain M46(T) was affiliated to the genus Sphingobacterium, exhibiting the highest sequence similarity of 97.9 % to Sphingobacterium ginsenosidimutans THG 07(T). Sphingobacterium canadense CR11(T) and Sphingobacterium detergens 6.2 S-T. Multilocus sequence analysis (MLSA) based on concatenated sequences of the rpoB, cpn60 and 16S rRNA genes showed that strain M46(T) clustered together with S. canadense CR11(T). The genome of strain M46(T) had a G+C content of 40.6 mol% and chromosome of 6 853 865 bp. Average nucleotide identity (ANI) between strain M46(T) and S. detergens 6.2 S-T and S. siyangense SY1(T) was 85.1 and 78.1 %, respectively. DNA-DNA relatedness values among strain M46(T) and other closely related Sphingobacterium species were <70 %. ANI and DNA-DNA relatedness findings strongly supported M46(T) as a putative novel strain of Sphingobacterium. The predominant fatty acids of strain M46(T) were iso-C-15:0, summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c) and iso-C-17:0 3-OH, and MK-7 was the dominant isoprenoid quinone. The polar lipid profile of strain M46(T) contained phosphatidylethanolamine as the dominant component, while minor amounts of phosphoglycolipid, one unidentified aminophospholipid, two unidentified phospholipids and four unidentified lipids were also detected. Based on 16S rRNA gene sequence similarities, MLSA results, genomic characteristics, and phenotypic and biochemotaxonomic analyses, strain M46(T) is considered to represent a novel species in the genus Sphingobacterium, for which the name Sphingobacterium athyrii sp. nov. is proposed. The type strain is M46(T) (=CGMCC 1.13466(T)=JCM 32543(T)).