The Zhoushan Halophilic Bacteria Producing Extracellular Polysaccharide Strain

Totally 120 aerobic or facultative anaerobic halophilic isolates obtained from different solar salterns and coasts located in the Zhoushan Archipelago, China. Most of the isolates are moderately halophilic or halotorant, and thereinto, white colonies are dominant while red and yellow colonies are also plurality. Cells of the isolates are mainly cocci or rod-shaped, and approximately 81.6 % of the strains are Gram-negative. The optimum salt concentration for strains from saline and marine are 3-15% and 2% NaCl, respectively. Strains commonly grow well at the concentration of 0.01-0.02mol/L Mg²⁺, but it is unnecessary and high concentration could restrain strains growing . Metal sensitivity of 13 EPS (exoploysaccharide) -producing strains is tested , of which HS223, HS239, HS254 survive from 2mg / mL Mn²⁺ ,HS246 survive from 1mg / mL Mn²⁺ , and all tested strains grow well in 10 μ g /mL Cr⁶⁺. No surfactant activity tested in this study.Based on the morphological, physiological and biochemical investigation, thirty-five strains were selected for phylogenetic analysis using their 16S rRNA gene sequences. The results showed that the representative strains could be allocated into three clades, 15 strains of gammaproteobacteria (43%), 11 strains of low GC gram-positive bacteria (31%), and 9 strains of halophilic archaea (26%). Additionally, some new species candidates were found based on similarities of the 16S rDNA sequences to previously published species.lt was considered that YT236, ZJ203 , ZJ204 or ZJ206 is a novel species of the genus Haloferax , HS234 is a novel species of the genus Chromohalobacter.This study will provide basic data for halophiles in Zhoushan Islands. Although the results showed remarkable microbial diversity, the discovery of novel species and strains of Chromohalobacter and Haloferax, in the relatively small number of sites from the Zhoushan Archipelago, indicated that there is still much to be learned about the diversity of these halophilic microorganisms.