T. FOOPHOW AND J. TANGJITJAROENKUN
Abstract
Proteases from microorganisms with highly specific activities and high resistance to salt have been an increasing interest because they have potential uses in various industrial fields, mainly in the food industry and detergent. In this research, protease producing bacteria from the sediments of three mangrove forests in Chanthaburi were isolated, screened and identified. 46 isolates exhibited proteolytic activity on SKA containing 3%NaCl. High bacterial diversity was found in sediments from Mangrove Forest Resources Development Station 2, Thason. The results of 16S rRNA sequence analysis showed that 45 isolates were related to Bacillus sp., whereas only isolate TS32 was related to Rhodococcus sp. 13 isolates exhibited high proteolytic activity based on a clear zone diameter of more than 10 mm. They can be divided into 3 groups: related to B. aquimaris TF-12, B. aryabhattai B8W22 and B. gibsonii DSM8722. Among these isolated bacteria, isolate KB111, similar to strain TF-12, exhibited maximum enzymatic activity (47±1.03 U/mL). The optimum temperature and pH for its activity were 40ºC and 7.0, respectively. According to the effect of salinity, isolate KB111 is a moderately halophilic bacteria. In Chanthaburi, mangrove forest sediments have high diversity of protease-producing bacteria; these bacteria have appropriate characteristics for application in industrial fields.