Abstract:
Hyperthermophiles are microorganisms that grow in high-temperature environments (80-100°C). Their thermozymes have high commercial relevance. This study aims to purify and characterize the keratinolytic protease from an extremely thermophilic Fervidobacterium sp. strain FA004 a indigenous stream to Thailand, closely related to Fervidobacterium thailandense type strain ATCC BAA-2483T. The strain FA004 was cultured in 480GM5 medium at 80°C for 48 h. The crude protease was harvested from culture supernate by (NH4)2SO4 precipitation (20-60% saturation) and then purified by using DEAE Sephacel and Sephadex G-100 column, respectively. The purified protease had the specific activity of 54.98 unit/mg protein with increased purity and yield of 89.27 fold and 10.37%, respectively. The zymogram showed three bands of caseinolytic activity which 67 kDa band have 86% intensity, suggesting fervidolysin form. The optimum pH and temperature of the protease were found to be 9.0 and 80°C, respectively. Furthermore, the protease show activity in range of pHs (7.0-9.0) and temperatures (70-90°C), and show thermostability with half-life values of >12h at 70°C, >10 h at 80°C and <1h at 90°C. The proteolytic activity was inhibited in the presence of phenylmethanesulfonyl fluoride (PMSF), indicating the serine protease activity. The protease posseses a keratinolytic activity on chicken feather. Both crude protease and purified were able to digest chicken feather. Approximately of 40% weight loss was obtained within 5 day at 80°C. The thermostable keratinolytic protease from strain FA004 could be of relevance for biotechnological application to offers an alternative method for value enhancement of keratin materials.