Metabolic engineering of Escherichia coli to optimize melanin synthesis from glucose

Microbial Cell Factories

Research

Alfredo Martinez¹  Francisco Bolívar¹  Guillermo Gosset¹  María I Chávez-Béjar¹  Aída Gutiérrez-Alejandre²  Victor E Balderas-Hernandez³ 

[1] Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, CP 62271, Cuernavaca,, Morelos, México;Departamento de Ingeniería Química, UNICAT, Facultad de Química, Universidad Nacional Autónoma de México, México, DF, México;Laboratorio de Biología Integrativa de Plantas y Microorganismos, Unidad Académica de Ciencias Biológicas, Universidad Autónoma de Zacatecas, Av. Preparatoria s/n, Col. Agronómica, CP 98066, Zacatecas, México;

关键词: Melanin;    L-tyrosine;    Tyrosinase;    Metabolic engineering;    Escherichia coli;   

DOI  :  10.1186/1475-2859-12-108

 received in 2013-08-13, accepted in 2013-11-05,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundNatural aromatic polymers, mainly melanins, have potential and current applications in the cosmetic, pharmaceutical and chemical industries. The biotechnological production of this class of compounds is based on tyrosinase-dependent conversion of L-tyrosine and other aromatic substrates into melanins. The purpose of this work was to apply metabolic engineering for generating Escherichia coli strains with the capacity to synthesize an aromatic polymer from a simple carbon source.ResultsThe strategy was based on the expression in E. coli of the MutmelA gene from Rhizobium etli, encoding an improved mutant tyrosinase. To direct the carbon flow from central metabolism into the common aromatic and the L-tyrosine biosynthetic pathways, feedback inhibition resistant versions of key enzymes were expressed in strains lacking the sugar phosphotransferase system and TyrR repressor. The expressed tyrosinase consumed intracellular L-tyrosine, thus causing growth impairment in the engineered strains. To avoid this issue, a two phase production process was devised, where tyrosinase activity was controlled by the delayed addition of the cofactor Cu. Following this procedure, 3.22 g/L of melanin were produced in 120 h with glucose as carbon source. Analysis of produced melanin by Fourier transform infrared spectroscopy revealed similar characteristics to a pure eumelanin standard.ConclusionsThis is the first report of a process for producing melanin from a simple carbon source at grams level, having the potential for reducing production cost when compared to technologies employing L-tyrosine as raw material.

【 授权许可】

Unknown   
© Chávez-Béjar et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.