全细胞催化生产苯乙酰-7-氨基-3-脱乙酰氧基头孢烷酸的条件优化

Optimization of whole-cell biocatalysis for phenylacetyl- 7-aminodeacetoxycephalosporanic acid production

摘要:

头孢类抗生素由于广谱性和低毒性被广泛用于细菌感染的治疗。7-氨基-3-脱乙酰氧基头孢烷酸 (7-aminodeacetoxycephalosporanic acid，7-ADCA) 作为半合成头孢类抗生素的重要中间体，需求量逐渐增加，而7-ADCA主要由G-7-ADCA (苯乙酰-7ADCA) 脱酰基得到。工业上多以化学法合成G-7-ADCA，成本高，污染严重。迫切需要对环境友好且经济高效的合成方法。在前期研究中，构建了一株可以将青霉素G转化为G-7-ADCA的代谢工程菌 (E. coli H7/PG15)。本研究通过单因素试验对E. coli H7/PG15的G-7-ADCA合成过程进行优化，包括底物组成及其最适浓度，转化条件 (菌体浓度、pH、青霉素浓度、MOPS浓度、葡萄糖浓度，铁离子浓度和时间等)。优化后，建立了全细胞催化法生产G-7-ADCA的工艺流程，使G-7-ADCA的产量稳定在15 mmol/L左右，转化率达到30%，具有操作简便、高效和经济的优势。

Abstract:

Cephalosporins are widely used antibiotics owing to their broad activity spectra and low toxicity. Many of these medically important compounds are made chemically from 7-aminodeacetoxycephalosporanic acid. At present, this intermediate is made by synthetic ring-expansion of the inexpensive penicillin G to form G-7-ADCA, followed by enzymatic removal of the side chain to obtain 7-ADCA. The chemical synthetic process is expensive, complicated and environmentally unfriendly. Environmentally compatible enzymatic process is favorable compared with chemical synthesis. In our previous research, metabolic engineered E. coli strain (H7/PG15) was constructed and used as whole-cell biocatalyst for the production of G-7-ADC with penicillin G as substrate. The whole-cell biocatalysis was studied by single factor experiment, including the composition of substrates and the conversion conditions (OD600, pH, concentration of penicillin G, MOPS, glucose, time and FeSO4). After optimization, 15 mmol/L of G-7-ADCA was obtained. The process is convenient, efficient and economic. This work would facilitate the industrial manufacturing and further product research.