Isolation, screening and identification of bacteria producing thermostable protease

The various benefits of thermostable protease have been increasingly known for use in industrial applications. Thus, the aim of this research is to isolate, screen, and identify bacteria that produce thermostable protease. To study the capability of bacteria to produce thermostable protease, samples were isolated from two hot spring namely Lo Chang Kra Hot spring (LK)and Khoa Chaison Hot spring (KS) at Patthalung Province, Thailand. Collected samples were tested on 4% skim milk agar and incubated AT 60°C for two days. Each colony producing clear zone was isolated and label according to its source (LK and KS). Among 30 isolates, only 13 isolates showed good proteolytic activity. These isolates were then further identified to be of Bacillus spp., Lactobacillus spp., Pseudomonas spp., and Aeromonas spp., based on Bergey's Manual of Determinative Bacteriology. Among 13 strains, LK18 which was Bacillus sp., showed the highest relative proteolytic activity (RPA)of 10 mm on skim milk agar. Therefore, it is a good candidate to be further identified and applied into the biotechnology industry as a good producer of thermostable protease.