Isolation and genomics of ten novel Shewanella species from mangrove wetland.

Mangrove bacteria largely compose the microbial community of the coastal ecosystem and are directly associated with nutrient cycling. In the present study, 12 Gram-negative and motile strains were isolated from a mangrove wetland in Zhangzhou, China. Pairwise comparisons (based on 16S rRNA gene sequences) and phylogenetic analysis indicated that these 12 strains belong to the genus . The 16S rRNA gene sequence similarities among the 12 strains and their related type strains ranged from 98.8 to 99.8 %, but they still could not be considered as known species. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the 12 strains and their related type strains were below the cut-off values (ANI 95-96% and dDDH 70 %) for prokaryotic species delineation. The DNA G+C contents of the present study strains ranged from 44.4 to 53.8 %. The predominant menaquinone present in all strains was MK-7. The present study strains (except FJAT-53532) also contained ubiquinones (Q-8 and Q-7). The polar lipid phosphatidylglycerol and fatty acid iso-C was noticed in all strains. Based on phenotypic, chemotaxonomic, phylogenetic and genomic comparisons, we propose that these 12 strains represent 10 novel species within the genus , with the names sp. nov. (FJAT-53749=GDMCC 1.2398=KCTC 82649), sp. nov. (FJAT-52072=MCCC 1K05363=KCTC 82447), sp. nov. (FJAT-53764=GDMCC 1.2349=KCTC 82648), sp. nov. (FJAT-53870=GDMCC 1.2346= KCTC 82640), sp. nov. (FJAT-53555=GDMCC 1.2344=KCTC 82645), sp. nov. (FJAT-53532=GDMCC 1.2343=KCTC 82644), sp. nov. (FJAT-54031=GDMCC 1.2347=KCTC 82642), sp. nov. (FJAT-53681=GDMCC 1.2345=KCTC 82641), sp. nov. (FJAT-51860=GDMCC 1.2342=KCTC 82650) and sp. nov. (FJAT-51754=GDMCC 1.2341= KCTC 82647).