Pusillimonas caeni sp. nov., isolated from a sludge sample of a biofilm reactor.

A polyphasic taxonomic study was carried out on strain EBR-8-1(T) isolated from a biofilm reactor in Korea. The cells of the strain were Gram-stain negative, non-spore-forming, non-motile, and short rod-shaped. Comparative 16S rRNA gene sequence studies showed a clear affiliation of this strain with Betaproteobacteria, which showed high pairwise sequence similarities with Pusillimonas noertemannii BN9(T) (99.1 %), Pusillimonas soli MJ07(T) (97.3 %), Pusillimonas ginsengisoli DCY25(T) (97.2 %), and Pusillimonas harenae B201(T) (96.8 %). The phylogenetic analysis based on 16S rRNA gene sequences showed that the strain formed a clear phylogenetic lineage within the genus Pusillimonas. The major fatty acids were identified as C16:0, C17:0 cyclo and C19:0 cyclo ω8c. The major cellular polar lipids were identified as phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and an unidentified aminolipid. The respiratory quinone was identified as Q-8 and the genomic DNA G+C content was determined to be 63.3 mol%. On the basis of polyphasic evidence, it is proposed that strain EBR-8-1(T) should be placed in a new species, Pusillimonas caeni sp. nov. The type stain is EBR-8-1(T) (=KCTC 42353(T) = JCM 30463(T)).