Phylogenetic diversity of cultivable bacteria associated with a sea anemone from coast of the Naozhou island in Zhanjiang, China

Abstract:

[Objective] To understand the diversity of cultivable bacteria isolated from a sea anemone collected from the coastal water of the Naozhou island in the Leizhou Bay on South China Sea. [Methods] Bacteria were isolated from a sea anemone by using conventional culture-dependent method and investigated by using phylogenetic analysis based on 16S rRNA gene sequence comparisons. [Results] We isolated 126 bacteria strains from the sample on marine agar 2216 (Difco), International Streotomyces Project medium 2 agar, nutrient agar, sea water agar and humic acid agar supplemented with 0–2 mol/L NaCl. Based on partial morphological, physiological and biochemical characteristics, we selected 42 strains for molecular systematic study based on 16S rRNA gene sequences. Our results showed that 42 isolates were members of eighteen genera (Alteromonas, Bacillus, Brachybacterium, Brevibacterium, Halobacillus, Halomonas, Nocardiopsis, Oceanobacillus, Piscibacillus, Planococcus, Pontibacillus, Pseudoalteromonas, Pseudonocardia, Salinicoccus, Salinivibrio, Staphylococcus, Vibrio, Virgibacillus) of eleven families (Alteromonadaceae, Bacillaceae, Brevibacteriaceae, Dermabacteraceae, Halomonadaceae, Planococcaceae, Pseudoalteromonadaceae, Pseudonocardiaceae, Nocardiopsaceae, Staphylococcaceae, Vibrionaceae) in three major phylogenetic groups (Actinobacteria, Firmicutes, Gamma-Proteobacteria). The most abundant and diverse isolates were within the phylum Firmicutes (40.5 %) and the subphylum Gamma-Proteobacteria (33.3 %). The phylogenetic distance matrix results suggested that, out of 42 isolates, 37 were different strains of 19 known species, and that at least 6 strains represented 6 new species within 6 characterized genera. [Conclusion] The results presented above showed that there were abundant species diversity and phylogenetic diversity of bacteria isolated from the sea anemone.

Key words:sea anemone; cultivable bacteria; 16s rRNA gene; phylogenetic analysis; bacterial diversity