Biotransformation is the chemical modification(or alteration) of chemical compounds like amino acids, toxins, xenobiotics and drugs, brought about by an organism to produce bioactive molecules. Penicillium jensenii isolated from soil (rhizosphere zone) was found to be a potent tyrosinase producer. Tyrosinase is capable of bringing about biotransformation of a single amino acid tyrosine to L-DOPA (3, 4- dihydroxyphenylalanine) and alpha methyl DOPA. L-DOPA is converted into dopamine in the brain and body by the enzyme L-aromatic amino acid decarboxylase which is further responsible for all kinds of the voluntary movements of the body. The by-product Alpha methyl DOPA is equally commercially viable as an important anti hypertensive and psychoactive drug. Since L-DOPA remains the gold standard for the treatment of Parkinson's disease, its production using microorganisms can hold a promising future for the small molecule pharmaceutical industry.