해수로부터 Urease 활성 Photobacterium sp. Strain HA-2 분리

Isolation of Urease-Positive Photobacterium sp. Strain HA-2 from Sea Water

Urease catalyzes the hydrolysis of urea into ammonia and carbamate. The latter spontaneously decomposes into another ammonia molecule and carbonic acid. We isolated a urease-positive bacterium from seawater on the western coast of Gomso bay in Korea. Using biochemical, morphological, and 16S rRNA gene analyses, we identified the bacterium as a Photobacterium sp. and named it Photobacterium sp. strain HA-2. We observed that the Photobacterium sp. strain HA-2 showed a 2.0-fold difference in urease activity, when cultured in an LB medium containing 3% NaCl with or without 0.1% urea (0.1620 vs. 0.0820 μmol NH3min/mgprotein) In this study, we also cloned and sequenced a ca. 15-kb DNA fragment from the chromosome of Photobacterium sp. strain HA-2, containing the urease gene clusters. We found ten open reading frames (ORFs) and the GC-content (40.9%) showed almost a perfect resemblance to the total genome of Photobacterium damselae subsp. damselae (40%). The urease gene cluster consisted of seven genes, and its genetic organization and sequences resembled those found in Vibrio parahaemolyticus and Vibrio fischeri.