%0 Journal Article
%T High performance microbiological transformation of L-tyrosine to L-dopa by Yarrowia lipolytica NRRL-143
%A Sikander Ali
%A Jeffry L Shultz
%A Ikram-ul-Haq
%J BMC Biotechnology
%D 2007
%I BioMed Central
%R 10.1186/1472-6750-7-50
%X Pre-grown cells of Yarrowia lipolytica NRRL-143 were used for the microbiological transformation of L-tyrosine to L-dopa. Different diatomite concentrations (0.5¨C3.0 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 Yp/s, Qs and qs over the control were observed.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 ¡Ü 0.05) by Y. lipolytica NRRL-143. A 35% higher substrate conversion rate was achieved when compared to the control.The yeast Yarrowia lipolytica is a hemiascomycete and represents a homogeneous phylogenetic group with physiological and ecological diversity [1]. It is a non-conventional yeast, often used in research and isdistantly related to Candida glabrata, Kluyveromyces lactis and Debaryomyces hansenii. Strains of Y. lipolytica can produce significant amounts of intra- or extra-cellular metabolites including vitamins, lipases, storage lipids, citric acid and pyruvic acid and can be used for biodegradation of various wastes (e.g., olive-mill waters and raw glycerol) [2-6]. The 3,4-dihydroxy phenyl L-alanine (L-dopa) is a drug used for Parkinson's disease, and is capable of changing the enzymes of energy metabolism of myocardium following neurogenic injury. The process of bioconversion of L-tyrosine to L-dopa in microorganisms is generally slow, but is accelerated by a small amount of L-dopa in the broth [7]. L-dopa has also been produced with Erwinia herbicola cells carrying a mutant transcriptional regulator TyrR from pyrocatechol and DL-serine [8,9]. It can also be produced using L-tyrosine
%U http://www.biomedcentral.com/1472-6750/7/50