利用基因组改组技术提高短杆菌素产量及其培养条件优化*

短杆菌素是一种广谱抗菌肽,对细菌和真菌均有较好的抑制作用,具有潜在的抗生素替代价值。通过对侧孢短芽孢杆菌fmb70进行紫外诱变、亚硝基胍诱变、常压室温等离子体诱变,获得3株短杆菌素产量提高的诱变菌株。随后以诱变菌株为亲本进行两轮基因组改组,获得融合子F₂-24,其短杆菌素产量为(340.5±16.35) μg/mL,是野生菌株fmb70短杆菌素产量的1.92倍。融合子传代5代后,该菌株短杆菌素产量无明显差异,说明菌株稳定性良好。最后对该菌株产短杆菌素的培养基和发酵条件进行优化,优化后的培养基为:4%蔗糖、2%牛肉膏、0.5%氯化镁,发酵温度30℃、培养24 h、培养基初始pH6.0。优化后的短杆菌素产量可达(442.45±9.58)μg/mL,是初始培养条件的2.50倍。

Breeding of Brevibacillin Producing Strain by Genome Shuffling and Optimization of Culture Conditions

Brevibacillin, a broad-spectrum antimicrobial peptide, has shown strong antibacterial effect on bacteria and fungi, which can be regard as a kind of potential substitute for antibiotics. The wild strain Brevibacillus laterosporus was carried out the conventional mutagenesis techniques including UV mutagenesis, atmospheric and room temperature plasma mutagenesis and nitrosoguanidine mutagenesis to obtain four mutant strains. After two rounds of genome shuffling, strain F₂-24 was obtained, and the yield of brevibacillin reached (340.5±16.35) μg/mL, which was 1.92-fold than that of wild strain fmb70. Furthermore, the fusion strain F₂-24 possessed great stability after five generations. Finally, the fermentation process of fusion strain F₂-24 was optimized. The results of the best carbon source, nitrogen source and inorganic salt ion was sucrose, beef extract and Mg ²⁺, respectively and the addition dose was 4%, 2% and 0.5%, respectively. The yield of brevibacillin was significantly enhanced via fermentation at 30℃ pH6.0 for 24 h, and meanwhile, the results suggested that the yield of brevibacillin was remarkably improved by a series of optimization and the yield reached (442.45±9.58) μg/mL, which was 2.50-fold than that produced by wild strain fmb70.