Martínez Luz María, Martinez Alfredo, Gosset Guillermo
Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.
Front Bioeng Biotechnol. 2019 Oct 24;7:285. doi: 10.3389/fbioe.2019.00285. eCollection 2019.
The melanins constitute a diverse group of natural products found in most organisms, having functions related to protection against chemical and physical stresses. These products originate from the enzyme-catalyzed oxidation of phenolic and indolic substrates that polymerize to yield melanins, which include eumelanin, pheomelanin, pyomelanin, and the allomelanins. The enzymes involved in melanin formation belong mainly to the tyrosinase and laccase protein families. The melanins are polymeric materials having applications in the pharmaceutical, cosmetic, optical, and electronic industries. The biotechnological production of these polymers is an attractive alternative to obtaining them by extraction from plant or animal material, where they are present at low concentrations. Several species of microorganisms have been identified as having a natural melanogenic capacity. The development and optimization of culture conditions with these organisms has resulted in processes for generating melanins. These processes are based on the conversion of melanin precursors present in the culture medium to the corresponding polymers. With the application of genetic engineering techniques, it has become possible to overexpress genes encoding enzymes involved in melanin formation, mostly tyrosinases, leading to an improvement in the productivity of melanogenic organisms, as well as allowing the generation of novel recombinant microbial strains that can produce diverse types of melanins. Furthermore, the metabolic engineering of microbial hosts by modifying pathways related to the supply of melanogenic precursors has resulted in strains with the capacity of performing the total synthesis of melanins from simple carbon sources in the scale of grams. In this review, the latest advances toward the generation of recombinant melanin production strains and production processes are summarized and discussed.
黑色素是一类存在于大多数生物体中的天然产物，具有抵御化学和物理应激的功能。这些产物源于酚类和吲哚类底物的酶促氧化，这些底物聚合后产生黑色素，包括真黑素、褐黑素、脓黑素和异黑素。参与黑色素形成的酶主要属于酪氨酸酶和漆酶蛋白家族。黑色素是聚合物材料，在制药、化妆品、光学和电子工业中有应用。这些聚合物的生物技术生产是一种有吸引力的替代方法，可替代从植物或动物材料中提取黑色素，因为在这些材料中黑色素的浓度较低。已鉴定出几种具有天然黑色素生成能力的微生物。对这些生物体培养条件的开发和优化已产生了生成黑色素的方法。这些方法基于将培养基中存在的黑色素前体转化为相应的聚合物。随着基因工程技术的应用，已能够过表达编码参与黑色素形成的酶（主要是酪氨酸酶）的基因，从而提高黑色素生成生物体的生产力，并允许产生能够产生多种类型黑色素的新型重组微生物菌株。此外，通过修饰与黑色素生成前体供应相关的途径对微生物宿主进行代谢工程改造，已产生了能够从简单碳源以克规模进行黑色素全合成的菌株。在本综述中，总结并讨论了在生成重组黑色素生产菌株和生产工艺方面的最新进展。
