Papers by Author: Yoo Kyung Lee

Abstract: In the marine environment, biofilms cover most of the subtidal and intertidal solid surfaces. Culturable bacteria forming marine biofilms were isolated on artificial substrate called acrylic coupons. The bacterial isolates were identified through a comparison of 16S rDNA sequences. A total of 115 strains were cultured and identified, 45 of which showed the same sequences with other strains. Therefore, 70 strains were finally identified. The bacterial isolates belonged to a–Proteobacteria (32 isolates), g–Proteobacteria (12 isolates), CFB group bacteria (4 isolates), high GC Gram-positive bacteria (9 isolates), and low GC Gram-positive bacteria (13 isolates). The bacterial isolates may be used as standard bacteria to test new antifouling agent. They may also be utilized as useful bacteria to enhance the settlement of commercial algae and invertebrate larvae for aquaculture.

Abstract: To find a novel exopolysaccharide, marine bacterial strains were isolated from coastal regions of Korea. Strain 00SS11568 was then selected as it produced a mucous exopolysaccharide during the stationary phase in a batch culture. The isolate was identified as Alteromonas sp. based on its 16S rDNA sequence, morphological, and biochemical properties. The exopolysaccharide, designated as p-11568, exhibited an emulsifying ability. The Emulsification Index (E24) of 0.1% p- 11568 was 77.4% with an emulsified kerosene content, and was higher than those of commercial polysaccharides, such as xanthan gum (26.1%), gellan gum (1.3%), and sodium alginate (2.0%). p- 11568 was found to be composed of glucose and galactose as the main natural sugars in a molar ratio of 1.3:1, along with uronic acid (18.9%, w/w) and sulfate groups (1.2% w/w). The average molecular mass was 4.4 x 105 daltons by gel filtration chromatography. The effects of pH, temperature, inorganic compounds, and C and N sources were tested to obtain the optimal medium composition for the production of p-11568. Under optimal growth conditions with the M-11568 medium, 14.9 g of crude p-11568 per liter was obtained.