To get more comprehensive understandings about the microbial diversity near the seawater of Ulleung Island, East sea of Korea, the bacterial identification base on 16S rDNA and their carbon source utilization patterns were analysed through the six surface water samples collected at June 23 to 25, 2007. The results are as follows; the population densities of aerobic heterotrophic and oligotrophic bacteria were from 1.9±0.6×104~6.3±0.7 ×104 cfu ml−1 and from 1.7±0.4×103~2.5±0.4×103 cfu ml−1 during sampling periods, respectively. Among 121 isolated stains, the dominant taxa are Pseudoalteromonas spp. (30 colonies) and Alteromonas spp. (17 colonies). Thirty-senven species-level strains base on 16S rDNA sequencing data are identified, which comprised Gammaproteobacteria (14 strains), Alphaproteobacteria (6 strains), Flavobacteria (6 strains), Actinobacteridae (4 strains), Firmicutes (4 strains), Deinococci (2 strains), Betaproteobacteria (1 strains). The carbon utilization patterns by assay of Biolog-microplate, α-D-glucose are used by 88.9% of the 27 strains of Gram-negative bacteria and more than 80% of them also consumed L-arabinose, D-trehalose, L-alanine, and pyruvic acid methyl ester. On the other hand, all the 10 strains of Gram-positive bacteria used α-D-glucose, and more than 80% of them also exploited maltose, palatinose, D-trehalose, turanose, D-xylose, and pyruvic acid.

Samples were taken from the surface waters around Dokdo Island to measure the physico-chemical and microbiological water qualities from June 23 to 26, 2007. Water temperature and dissolved oxygen were in the range of 20.7~20.9oC and 7.01~7.74, respectively. Salinity and pH were in the range of 34.5~34.8‰ and 8.23~8.37, respectively. Population densities of aerobic oligotrophic bacteria and heterotrophic bacteria by plate counting method were in the range of 2.4±0.5×103~3.0±0.3×103 and 4.4±0.6×103~6.0±0.9×103 cfu ml−1, respectively. Among thirty-seven isolates isolated from surface waters around Dokdo island by using 16S rDNA analysis, dominant species were closely related to Actionobacteria (7 clones), α-proteobacteria group (6 clones), and γ-proteobacteria group (4 clones).