Cultivable Bacterial Diversity Of The East China Sea Taxonomy Of Two Bacteriums

Bacterial diversity of 14 sites of the East China Sea was investigated by culture-dependent methods. The impact of human activities on marine bacteria was primarily studied and characteristics of bacteria communities in different areas were analyzed. Two strains, Za3-36-1T and Za3-19, were studied by polyphasic taxonomy analysis in order to determine their taxonomic status.A total of 396 strains were obtained. These strains belong to 4 phyla, 9 classes and 146 species according to 16S rDNA sequences alignment. For 32 strains, the 16S rDNA sequences similarities between isolated strains and their most closely related species were lower than 98%. The result indicated that there are abundant microbial diversity and a large number of unknown microbial resources in the East China Sea. Isolated strains were dominated byγ-proteobacteria (64%),α-proteobacteria (18%) and Firmicutes (15%). Actinobacteria and Bacteroidetes were less than 3%. Microbial community composition, diversity and abundance among areas with varies distances from land were different. The far the regions from the land, the lower the Shannon index (H') and the Margalef index (D_Mg) values were. Firmicutes richness in near shore areas was much higher than areas far from the land, this phenomenon probably because that this kind of bacteria have high resistance ability of hostile parameters. In near shore areas, many strains which have the ability to breakdown organic pollutants or absorb heavy metals were isolated. Some other kinds of bacteria intend to appear at areas far from the land. Maybe these kinds of bacteria have harsh requirement of water environment.Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain Za3-36-1^T and Za3-19 clustered with members of the genus Glaciecola, exhibiting high sequence similarity to the 16S rRNA gene sequences of the type strains of G. pallidula (95.997% and 95.726%, respectively). Cells are aerobic, Gram-negative, motile and short rod shaped. Growth occurs at NaCl concentrations of 0.5-7.0 % (w/v). The pH and temperature ranges for growth are pH 6.0-10.0 and 4-32℃. No growth occurs without NaCl or Sea Salt. According to the result of API ZYM and API 20E/NE test, activities for acid and alkaline phosphatases, esterase (C4), esterase lipase (C8), leucine arylamidase,β-glucosidase,α-chymotrypsin and naphthol -AS-β-1-phosphohydrolase are positive. Glucose, inositol, sorbitol, rhamnose, sucrose, melibiose, amygdalin, arabinose, maltose and adipic acid can be used as sole carbon source. H2S was not produced. Nitrate reduction is negative. Susceptible to streptomycin and tetracyline, but not susceptible to Vancomycin,erythrocin,rifampicin,polymyxin B and novobiocin. The major fatty acids are Sum In Feature 3 (C_{16 : 1}ω7c and/or iso- C_{15 : 0} 2OH) and C_{16 : 0}/iso- C_{16 : 0}. The DNA G+C content of Za3-36-1^T and Za3-19 were 42.8% and 41.7%, respectively. On the basis of phenotypic, chemotaxonomic and phylogenetic data that distinguish strain Za3-36-1^T and strain Za3-19 from the other Glaciecola species, we suggest that these two strains represents a novel species of the genus Glaciecola, for which the name Glaciecola donghaiensis sp. nov. is proposed.