Cysteiniphilum marinum sp. nov., isolated from coastal seawater

Six aerobic Gram-negative bacteria were isolated from seawater in Guangdong Province, P.R. China. Cells were observed to be Gram-negative, aerobic, non-motile and non-spore forming. Growth of the designated type strain 19X3-30(T) occurred at a temperature range of 14-37 degrees C (optimum, 28 degrees C), a pH range of 6.0-8.0 (optimum, pH 7) and up to 7.5% NaCl (optimum, 1.5%; w/v), and was enhanced by CO2 and L-cysteine supplementation. The major polar lipids identified in strain 19X3-30(T) were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The principal cellular fatty acids profile showed the presence of anteiso-C-15:0, anteiso-C-17:0 and C-18:0 (> 8% of total fatty acids), and the respiratory quinone was ubiquinone 8 (UQ-8). According to the analysis of 16S rRNA gene sequences, these strains represented a novel species within the family Fastidiosibacteraceae, sharing maximum similarities with Cysteiniphilum litorale DSM 101832(T) (96.6%) and Cysteiniphilum halobium DSM 103992(T) (95.3%). Phylogenetic dendrograms based on 16S rRNA gene and protein marker genes from the genomic sequences both indicated that the strains formed a monophyletic lineage closely linked to the genus Cysteiniphilum, which was also supported by the UPGMA dendrogram based on the MALDI-TOF MS profile. The genomic DNA G + C contents of six strains ranged from 38.0% to 38.1%. Based on different taxonomic genomic metrics, phylogeny and phenotypic features, we propose that the strains warrant the assignment to a novel species, for which the name Cysteiniphilum marinum sp. nov. is proposed. The type strain is 19X3-30(T) (= KCTC 82154(T) = CGMCC 1.18585(T)).

Automated summary

This study isolated six aerobic Gram-negative bacteria from seawater in Guangdong Province, China and identified a novel species named Cysteiniphilum marinum. Various taxonomic genomic metrics, phylogeny and phenotypic features supported the assignment of these strains to a new species.