Microbial Transformation of Steroids: a Focus on Types and Techniques

Steroids are widespread in nature and are important compounds present in living systems. These compounds include different sterols, bile salts and steroid hormones like estrogen, androgens, testosterones etc. and have numerous therapeutic applications. Microbial biotransformation of steroids is one of the applications of microorganisms in the large-scale industries and it also have certain advantages over the chemical processes of steroid production. For biotransformation process, precursor steroids are required which are transformed in to valuable intermediates as well as the final transformed product. Different types of biotransformation reactions are used for the process of microbial biotransformation which include hydroxylation, dehydrogenation, side-chain degradation, ring A aromatization and reduction. Biotransformation of steroids can be done by different techniques and approaches like biotransformation in aqueous medium, biotransformation using immobilized cells and enzymes, biotransformation using free enzymes and biotransformation in biphasic systems. Different biotransformation facilitators are also used for enhancement of product yield. Alternate Biotransformation systems using liposomes and microemulsions are also being used for microbial steroid biotransformation.