Improving the Production and Properties of Microbial Proteases by Genetic Engineering

Genes of different microbial proteases were cloned for the overproduction of enzymes with food, biomedical, and detergent applications. These microbial proteases include different subtilisin enzymes, neutral protease, different alkaline proteases, aspartic protease, aspergillopepsin, acidic protease, and proteinase K. Proteases were also genetically modified to obtain more pH-resistant, more substrate-specific, thermostable, less autocatalytic, and halotolerant enzymes. Proteases from Bacillus, Aspergillus, Acremonium, Tritirachium species were cloned into Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae. Aminopeptidases are widely applied in the food industry for controlling bitterness in protein hydrolysates and improving flavor in fermented foods, and advancements like codon optimization in genetic engineering have focused on improving the stability of aminopeptidases. Serine proteases like Carlsberg protease, derived from B. licheniformis, and subtilisin, from B. amyloliquefaciens, have been genetically modified for better performance in detergent applications. Site-directed mutagenesis was used to improve the catalytic efficiency and thermal stability of cysteine proteases, and these proteases are commercially used for meat tenderization, baking, leather processing, wound treatment, anticancer therapy, and treating inflammatory diseases. Recent developments on the improvement of production and properties of microbial proteases by genetic engineering will be discussed here.