地衣芽孢杆菌氮源响应启动子的挖掘、鉴定及应用

Promoters are important expression elements in synthetic biology. Bacillus licheniformis is a chassis cell with excellent production performance, but the types and quantities of promoter elements are particularly limited. The existing two types of promoters, grouped and carbon source-induced, have shortcomings in terms of expression strength and diversification in response to environmental signals. Nitrogen source, like carbon source, is also an essential nutrient for microbial growth. The development of nitrogen-responsive promoters is of great significance for enriching the components of synthetic biology and improving the performance of chassis cells. In this study, firstly, the promoter elements responsive to nitrogen sources were predicted based on genomic information, and the green fluorescent protein gene egfp was used as the reporter gene [1] to evaluate the initiation transcription characteristics. It was found that PglnR and Pgcv could respond to glutamate initiation transcription, and the initiation transcription intensity of PglnR and Pgcv was 2.5 times that of the control group. Furthermore, the selected promoters PglnR and Pgcv were used to mediate the expression of transglutaminase gene (TGase) from S. mutaraensis. The recombinant strain was incubated at 37 ℃ with 10 g/L soluble starch and 10 g/L glutamine, and the highest extracellular enzyme activity reached 2.61 U/mL. The mining, identification and application of the new nitrogen-responsive promoters lay a foundation for improving the expression system of Bacillus licheniformis.