dentification of a new marine bacterium Ruegeria sp. 50C-3 isolated from seawater of Uljin in Korea and production of thermostable enzymes
2016
Chi, W.J., National Institute of Biological Resource, Incheon, Republic of Korea | Kim, J.H., Seoil University, Seoul, Republic of Korea | Park, J.S., Myongji University, Yongin, Republic of Korea | Hong, S.K., Myongji University, Yongin, Republic of Korea
A marine bacterium, designated as strain 50C-3, was isolated from a seawater sample collected from the East Sea of South Korea. The strain is a Gram-negative, aerobic, yellow colored polar-flagellated bacterium that grows at 20-50Celsius and pH 5.5-8.5. Optimal growth occurred at 40-50Celsius, at pH 6.5-7.5, and in the presence of 2% (w/v) NaCl. Based on 16S rRNA gene sequence similarity, the isolate was considered to represent a member of the genus Ruegeria. The result of this analysis showed that strain 50C-3 shared 99.4% and 96.98% sequence similarity with Ruegeria intermedia CC-GIMAT-2T and Ruegeria lacuscaerulensis ITI-1157T , respectively. Furthermore, strain 50C-3 showed clear differences from related strains in terms of several characteristics such as motility, carbon utilization, enzyme production, etc. The DNA G+C content was 66.7 mol%. Chemotaxonomic analysis indicated ubiquinone-10 (Q-10) as the predominant respiratory quinone. Based on phenotypic, chemotaxonomic, and phylogenetic characteristics, the isolate represents a novel variant of the Ruegeria intermedia CC-GIMAT-2T , for which we named Ruegeria sp. 50C-3 (KCTC23890=DSM25519). Strain 50C-3 did not produce cellulase and agarase, but produced alkaline phosphatase, alpha-galactosidase, and beta-galactosidase. The three enzymes showed stable activities even at 50Celsius and thus regarded as thermostable enzymes. Especially, the beta-galactosidase activity enhanced by 1.9 times at 50Celsius than that at 37Celsius, which may be very useful for industrial application.
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