State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.
Sci Rep. 2017 Jan 23;7:40976. doi: 10.1038/srep40976.
Natural Bacillus isolates generate limited amounts of surfactin (<10% of their biomass), which functions as an antibiotic or signalling molecule in inter-/intra-specific interactions. However, overproduction of surfactin in Bacillus amyloliquefaciens MT45 was observed at a titre of 2.93 g/l, which is equivalent to half of the maximum biomass. To systemically unravel this efficient biosynthetic process, the genome and transcriptome of this bacterium were compared with those of B. amyloliquefaciens type strain DSM7. MT45 possesses a smaller genome while containing more unique transporters and resistance-associated genes. Comparative transcriptome analysis revealed notable enrichment of the surfactin synthesis pathway in MT45, including central carbon metabolism and fatty acid biosynthesis to provide sufficient quantities of building precursors. Most importantly, the modular surfactin synthase overexpressed (9 to 49-fold) in MT45 compared to DSM7 suggested efficient surfactin assembly and resulted in the overproduction of surfactin. Furthermore, based on the expression trends observed in the transcriptome, there are multiple potential regulatory genes mediating the expression of surfactin synthase. Thus, the results of the present study provide new insights regarding the synthesis and regulation of surfactin in high-producing strain and enrich the genomic and transcriptomic resources available for B. amyloliquefaciens.
天然芽孢杆菌分离株产生的表面活性剂数量有限（<其生物量的 10%），在种间/种内相互作用中作为抗生素或信号分子发挥作用。然而，在解淀粉芽孢杆菌 MT45 中观察到表面活性剂的过量生产，产量为 2.93g/l，相当于最大生物量的一半。为了系统地揭示这种高效的生物合成过程，将该细菌的基因组和转录组与解淀粉芽孢杆菌标准菌株 DSM7 的基因组和转录组进行了比较。MT45 具有较小的基因组，同时包含更多独特的转运蛋白和耐药相关基因。比较转录组分析显示，MT45 中表面活性剂合成途径明显富集，包括中央碳代谢和脂肪酸生物合成，以提供足够数量的构建前体。最重要的是，与 DSM7 相比，MT45 中模块化表面活性剂合成酶的表达（9 至 49 倍）显著上调，表明表面活性剂的组装效率更高，导致表面活性剂的过量生产。此外，根据转录组中观察到的表达趋势，有多个潜在的调节基因介导表面活性剂合成酶的表达。因此，本研究的结果为高产菌株中表面活性剂的合成和调控提供了新的见解，并丰富了解淀粉芽孢杆菌的基因组和转录组资源。
