Enzymes are important biocatalysts that exist naturally in all living organisms. Nowadays, enzymes have been widely applied to modern industries because biological catalysts are substratespecific, highly active and operate within mild environments. However, the cost of culturing proteinrich microorganisms as well as extracting and purifying the enzymes are high. One solution is to genetically modify the microorganisms for high protein expression. Therefore, this review discusses the mechanism of various mutagenesis techniques (physical and chemical) as well as the potential genetic modification to increase protein yields in microorganisms.