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<p>Abstract</p> <p>Background</p> <p>The 3,4-dihydroxy phenyl L-alanine (L-dopa) is a drug of choice for Parkinson's disease, controlling changes in energy metabolism enzymes of the myocardium following neurogenic injury. <it>Aspergillus oryzae </it>is commonly used for L-dopa production; however, potential improvements in ease of handling, growth rate and environmental impact have led to an interest in exploiting alternative yeasts. The two important elements required for L-dopa production are intracellular tyrosinases (thus pre-grown yeast cells are required for the transformation of L-tyrosine to L-dopa) and L-ascorbate, which acts as a reducing agent.</p> <p>Results</p> <p>Pre-grown cells of <it>Yarrowia lipolytica </it>NRRL-143 were used for the microbiological transformation of L-tyrosine to L-dopa. Different diatomite concentrations (0.5–3.0 mg/ml) were added to the acidic (pH 3.5) reaction mixture. Maximum L-dopa biosynthesis (2.96 mg/ml L-dopa from 2.68 mg/ml L-tyrosine) was obtained when 2.0 mg/ml diatomite was added 15 min after the start of the reaction. After optimizing reaction time (30 min), and yeast cell concentration (2.5 mg/ml), an overall 12.5 fold higher L-dopa production rate was observed when compared to the control. Significant enhancements in Y_p/s, Q_sand q_sover the control were observed.</p> <p>Conclusion</p> <p>Diatomite (2.0 mg/ml) addition 15 min after reaction commencement improved microbiological transformation of L-tyrosine to L-dopa (3.48 mg/ml; p ≤ 0.05) by <it>Y. lipolytica </it>NRRL-143. A 35% higher substrate conversion rate was achieved when compared to the control.</p>