Production and Characterization of Protease from an Extremely Halophilic Halobacterium sp. PB407

In order to accelerate the fish sauce fermentation by using enzyme, the production of protease from Halobacterium sp. PB407 isolated from Thai fish sauce was investigated. This strain could produce high protease inM73 medium containing 4 M (24%, w/v) NaCl, pH 7.0 at 37∞C in shaking condition for 5days. Its production of protease in 2.5 L mini jar fermentor was investigated at 37∞C, 50 rpm agitation and aeration at 0.5 vvm. The protease production time was shorten to only 96 hrs. The optimum pH and temperature for maximal protease activity was 8.0 and 40∞C, respectively. This protease had marked halophilic properties, showing maximum activities in the presence of 2.13 M NaCl. In addition, this Halobacterium sp. PB407 was further identified. Based on 16S rRNA sequence data, the bacteria was concluded as a Halobacterium salinarum.