Díez B, Mellado E, Fouces R, Rodríguez M, Barredo J L
Laboratorio de Ingeniería Genética, Antibióticos S. A., León, Spain.
Microbiologia. 1996 Sep;12(3):359-70.
Conventional strain improvement programs based on random mutagenesis and rational screening have meant valuable results to the antibiotic producing companies. The development of recombinant DNA techniques and their applications to the industrially-used cephalosporin-producing fungus Acremonium chrysogenum has provided a new tool, complementary to classical mutation, promoting the design of alternative biosynthetic pathways making it possible to obtain new antibiotics and to improve cephalosporin production. Yield increases have been achieved by increasing the dosage of the biosynthetic genes cefEF (deacetoxycephalosporin C expandase/hydroxylase) and cefG (deacetylcephalosporin C acetyltransferase) or enhancing the oxygen uptake by expressing a bacterial oxygen-binding heme protein (Vitreoscilla hemoglobin). New biosynthetic capacities such as the production of 7-aminocephalosporanic acid (7-ACA) or penicillin G have been achieved through the expression of the foreign genes dao (D-amino acid oxidase) coupled with cephalosporin acylase or penDE(acyl-CoA:6-APA acyltransferase) respectively. Confined manipulation of the above-mentioned recombinant strains must be performed according to standing rules.
基于随机诱变和合理筛选的传统菌株改良计划已为抗生素生产公司带来了有价值的成果。重组DNA技术的发展及其在工业用产头孢菌素的真菌产黄顶头孢霉中的应用提供了一种新工具，它是对经典诱变的补充，有助于设计替代生物合成途径，从而有可能获得新抗生素并提高头孢菌素产量。通过增加生物合成基因cefEF（去乙酰氧头孢菌素C扩环酶/羟化酶）和cefG（去乙酰头孢菌素C乙酰转移酶）的剂量，或通过表达一种细菌氧结合血红素蛋白（透明颤菌血红蛋白）来增强氧气摄取，实现了产量的提高。通过分别表达与头孢菌素酰化酶或penDE（酰基辅酶A：6-氨基青霉烷酸酰基转移酶）偶联的外源基因dao（D-氨基酸氧化酶），获得了新的生物合成能力，如生产7-氨基头孢烷酸（7-ACA）或青霉素G。必须根据现行规定对上述重组菌株进行严格操作。
