PDF(Pubmed)
Abstract：
Surfactants are amphiphilic molecules that are capable of mixing water and oil. Biosurfactants are eco-friendly, low-toxicity, and stable to a variety of environmental factors. Optimizing conditions for microorganisms to produce biosurfactants can lead to improved production suitable for scaling up. In this study, we compared heterologous expression levels of the luminescence system luxCDABE operon controlled by regulatable promoters araC-PBAD and its strong version araC-PBAD-SD in Escherichia coli K12, Pseudomonas aeruginosa PAO1, and P. putida KT2440. Real-time monitoring of luminescence levels in the three strains indicated that luxCDABE controlled by araC-PBAD-SD promoter with 0.2% arabinose supplementation in P. putida produced the highest level of luminescence. By using the araC-PBAD-SD promoter-controlled rhlAB expression in P. putida, we were able to produce mono-rhamnolipid at a level of 1.5 g L-1 when 0.02% arabinose was supplemented. With the same system to express olsB, lyso-ornithine lipid was produced at a level of 10 mg L-1 when 0.2% arabinose was supplemented. To our knowledge, this is the first report about optimizing conditions for lyso-ornithine lipid production at a level up to 10 mg L-1. Taken together, our results demonstrate that regulatable araC-PBAD-SD promoter in P. putida KT2440 is a useful system for heterologous production of biosurfactants.
摘要：
表面活性剂是能够混合水和油的两亲分子。生物表面活性剂是环保的，低毒性,对多种环境因素稳定。优化微生物生产生物表面活性剂的条件可以导致适于扩大规模的改进的生产。在这项研究中,我们比较了由可调节启动子araC-PBAD控制的发光系统luxCDABE操纵子及其强大版本araC-PBAD-SD在大肠杆菌K12，铜绿假单胞菌PAO1和恶臭假单胞菌KT2440中的异源表达水平。三个菌株中发光水平的实时监测表明，由araC-PBAD-SD启动子控制的luxCDABE在恶臭假单胞菌中补充了0.2％阿拉伯糖，产生了最高的发光水平。通过使用araC-PBAD-SD启动子控制的rhlAB在P.putida中的表达，当添加0.02％阿拉伯糖时，我们能够以1.5gL-1的水平生产单鼠李糖脂。用同样的系统来表达olsB，当补充0.2％阿拉伯糖时，以10mgL-1的水平产生溶血鸟氨酸脂质。据我们所知,这是关于优化溶血鸟氨酸脂质生产条件的第一份报告，其水平高达10mgL-1。一起来看,我们的结果表明，putidaKT2440中的可调节araC-PBAD-SD启动子是异源生产生物表面活性剂的有用系统。
