Agroindustrial/Forestry Residues as Substrates for Production of Thermoactive Alkaline Protease from Bacillus licheniformis K-3 Having Multifaceted Hydrolytic Potential

Microbial proteases due to their enormous application potential in numerous biotechnological processes have gathered considerable research impetus during recent years. However, lack of process suitable characteristics viz. thermostability, wide range pH stability, resistance to inhibitors, among others, in most of the available proteases motivated the search for better and efficient proteases. High production cost of microbial proteases mainly due to expensive substrates (carbon/nitrogen sources used for cultivation of microorganisms) is another limitation for wide range industrial application of these enzymes. Current investigation reports production of a thermostable and pH stable protease from a bacterial isolate Bacillus licheniformis K-3 using agroindustrial/forestry residues as inexpensive substrates for cost-effective enzyme production. Pine needle biomass is being reported for the first time as a proficient carbon source that supported maximum protease production (1321 U/ml), and was followed by wheat bran (1303 U/ml), potato peel (1167 U/ml) and cane bagasse (1122 U/ml). Gram husk as nitrogen source enhanced enzyme production maximally (932 U/ml) as compared to control (389 U/ml), and was followed by soybean meal (823 U/ml), malt extract (742 U/ml), mustard cake (724 U/ml) and fish scales (670 U/ml). Optimum pH and temperature for enzyme was 9.0 and 60 °C, however, protease showed considerable activity over high temperatures and broad pH range. Protease from B. licheniformis K-3 showed remarkable tolerance against detergents like CTAB, SDS and Tween-20. The protease exhibited excellent potential for industrial applications like degelatinization of X-ray films and dehairing of animal hide. Hydrolytic enzyme potential of bacterial isolate B. licheniformis K-3. Plates A–F indicates: culture morphology of bacterium (A), proteolytic activity (B), amylolytic (C), lipolytic (D) keratinolytic (E) gelatinolytic (F), and cellulolytic activity (G) of bacterial isolate