Production of Extracellular Protease from Bacterial Co-cultures using Solid State Fermentation

Abstract

Proteases (also known as peptidases or proteinases) are hydrolytic enzymes that cleave proteins into amino acids. They comprise 60% of the total industrial usage of enzymes worldwide and can be obtained from many sources. The current study aims to isolate and screen protease-producing bacterial strains from the soil and to produce protease from the bacterial co-cultures using solid-state fermentation (SSF). Primary screening of the protease-producing bacterial strains was carried out on skim milk agar and they were sub-cultured and preserved on the nutrient agar for further testing. Thirty-two compatibility tests of twenty-seven bacterial isolates were performed and SSF was carried out. Afterward, absorbance was taken at 660 nm against tyrosine as standard. According to the results, the bacterial co-culture 19 showed the highest absorbance with an enzyme activity of 10.2 U/ml. The bacterial strains of the co-culture 19 were identified through morphological and biochemical tests. Bacterial strain 1 was observed as cocci and irregular, while bacterial strain 2 was bacillus and rod-shaped. Both strains were positive for gram staining, catalase test, casein hydrolysis test and methyl red test. As for endospore staining, bacterial strain 1 was spore forming while bacterial strain 2 was a non-spore former. It was concluded that the bacterial co-culture 19 can act as a potent co-culture for protease production. Compatibility test was carried out to enhance the production of protease by utilizing cheap and readily available agro-waste products, which benefit the industry by being cost effective and the environment by being eco-friendly.