Bioprocess engineering aspects of a bacterial protease its cloning expression and applications

Abstract

Proteases are hydrolytic enzymes produced by microorganisms that catalyze the hydrolysis of peptide bonds present in proteins. Among all the micro-organisms, Bacillus species are the major source of protease producers for various industrial applications. Commercial proteases are mainly produced by submerged fermentation (SmF) although solid state fermentation (SSF) has also been studied to a lesser extent. Cost effective bioprocessing of protease was studied by using different commercial substrates and nutritional supplements. Fish meal (FM) is generally used as a food supplement for fish, poultry and animals due to its high nutritional value. It was used here to replace higher grade nutrient sources in the medium for protease production which proved to be an excellent source of nutrients to support the growth of Bacillus pumilus as well as protease production. Partial purification and concentration of crude filtrate obtained by the SmF of protease using Bacillus pumilus MTCC 7514 was studied thoroughly by different techniques viz., ammonium sulphate precipitation, flocculation, spray drying and ultrafiltration. Application of alkaline protease was thoroughly studied for depilation of leather and cell detachment in tissue culture. The potential of protease for depilation was good as the process was completed in 2-3 h for goat skin and 4 h for cow hide by employing precipitated protease preparation whereas depilation of cow hide took 4-5 h for ultrafiltered enzyme and 8 h for crude enzyme. The enzymatic depilation process was eco-friendly as it greatly reduced the pollution parameters viz. BOD, COD, TDS and TSS to an extent of 86.6, 83.5, 75 and 97%, respectively. The study of protease in detachment of cell lines showed that viability of cells obtained by protease treatment was equivalent to viability of trypsinized cells. newline