脉冲补料甜菜糖蜜对大肠杆菌BL21(DE3)生产重组苯甲醛裂解酶的影响。

Effects of pulse feeding of beet molasses on recombinant benzaldehyde lyase production by Escherichia coli BL21(DE3).

作者信息

Calik Pinar, Levent Hande

机构信息

Department of Chemical Engineering, Industrial Biotechnology and Metabolic Engineering Laboratory, Middle East Technical University, 06531, Ankara, Turkey.

出版信息

Appl Microbiol Biotechnol. 2009 Nov;85(1):65-73. doi: 10.1007/s00253-009-2060-2. Epub 2009 Jun 23.

DOI:10.1007/s00253-009-2060-2

PMID:19547969

Abstract

The effect of fed-batch operation (FBO) strategy was investigated using pretreated-beet molasses, containing galactose that induces the lac promoter, on benzaldehyde lyase (BAL) production by recombinant Escherichia coli BL21(DE3)pLySs. After batch cultivation with 30 g l(-1) pretreated-beet molasses consisting of 7.5 g l(-1) glucose and 7.5 g l(-1) fructose, three FBO strategies were applied at dissolved oxygen (=40%) cascade to air-flow rate. In FBO1 when air-flow rate decreased considerably, feed was given to the system in pulses in such a way that pretreated-beet molasses concentration increased by 10 kg m(-3) (containing 2.5 g l(-1) glucose+2.5 g l(-1) fructose); however, decrease in air-flow rate demonstrated only the absence of glucose but not fructose. Thus, in FBO2 when fructose and glucose were completely utilized, pretreated-beet molasses was pulse-fed and its concentration increased by 10 g l(-1). In FBO3 with the decreased amount of pretreated-beet molasses (6 g l(-1)), shift response time from glucose to fructose consumption was avoided, and glucose and fructose consumptions were well correlated with air-flow rate, and the highest CX (8.04 g l(-1)) and BAL (2,315 U ml(-1)) production were obtained (t=24 h) with the highest substrate yield on cell and product formation.

摘要

使用含有诱导乳糖启动子的半乳糖的预处理甜菜糖蜜，研究了分批补料操作（FBO）策略对重组大肠杆菌BL21(DE3)pLySs生产苯甲醛裂解酶（BAL）的影响。在以30 g l⁻¹由7.5 g l⁻¹葡萄糖和7.5 g l⁻¹果糖组成的预处理甜菜糖蜜进行分批培养后，在溶解氧（=40%）级联到空气流速的条件下应用了三种FBO策略。在FBO1中，当空气流速大幅下降时，以脉冲方式向系统进料，使预处理甜菜糖蜜浓度增加10 kg m⁻³（含有2.5 g l⁻¹葡萄糖 + 2.5 g l⁻¹果糖）；然而，空气流速的降低仅表明不存在葡萄糖而非果糖。因此，在FBO2中，当果糖和葡萄糖被完全利用时，对预处理甜菜糖蜜进行脉冲补料，其浓度增加10 g l⁻¹。在FBO3中，随着预处理甜菜糖蜜量的减少（6 g l⁻¹），避免了从葡萄糖消耗到果糖消耗的转换响应时间，葡萄糖和果糖的消耗与空气流速密切相关，并且在细胞和产物形成方面底物产率最高，在t = 24 h时获得了最高的CX（8.04 g l⁻¹）和BAL（2315 U ml⁻¹）产量。