抗生素对于对抗病原体至关重要;然而,它们的滥用导致了抵抗力的增加,必须寻找有效的,低毒性替代品。Surfactin,具有C12-C17β-羟基脂肪酸链的环状脂肽,表现出显著的抗菌活性和抗性,使其成为研究重点。尽管如此,支链氨基酸(BCAAs)对表面活性素结构和活性的影响尚不清楚。本研究考察了BCAAs(L-缬氨酸,L-亮氨酸,和L-异亮氨酸)上的脂肽(表面活性素)由VelezensisYA215产生。工艺优化表明,添加1g/L的L-Leu和L-Ile,和0.5g/L的L-Val,将表面活性肽的产量最大化至18.59%,19.23%,和20.64%,分别。L-Val和L-Ile在36小时时达到峰值,收益率为19.72%和11.37%。相比之下,L-Leu添加在24小时达到峰值,收益率11.33%。值得注意的是,L-Val补充导致最高的相对表面活性素含量。抗菌试验表明,BCAAs能显著增强脂肽对大肠杆菌和金黄色葡萄球菌的抗菌作用,Val表现出最明显的效果。BCAAs的添加显著改变了表面活性肽脂肪酸链的组成。具体来说,Val将isoC14和isoC16β-羟基脂肪酸的比例从13.3%和4.216-23.803%和8.31%增加,分别。此外,肽链第7位的氨基酸组成发生了显著变化,尤其是Val加法,使C14[Val7]表面活性素的比例提高了3.29倍。这些结构变化可能与表面活性素的抗菌活性增强有关。这些发现为BCAAs在微生物发酵中的作用提供了有价值的见解,强调它们在代谢工程中的重要性,以提高生物活性化合物的生产。
Antibiotics are essential for combating pathogens; however, their misuse has led to increased resistance, necessitating the search for effective, low-toxicity alternatives. Surfactin, a cyclic
lipopeptide with a C12-C17 β-hydroxy fatty acid chain, exhibits significant antibacterial activity and resists resistance, making it a research focus. Nonetheless, the effects of branched-chain amino acids (BCAAs) on surfactin\'s structure and activity are not well understood. This study examines the influence of BCAAs (L-valine, L-leucine, and L-isoleucine) on the
lipopeptide (surfactin) produced by Bacillus velezensis YA215. Process optimization shows that adding 1 g/L of L-Leu and L-Ile, and 0.5 g/L of L-Val, maximized surfactin production to 18.59%, 19.23%, and 20.64%, respectively. Surfactin content peaked at 36 h with L-Val and L-Ile, yielding 19.72% and 11.37%. In contrast, L-Leu addition peaked at 24 h, yielding 11.33%. Notably, L-Val supplementation resulted in the highest relative surfactin content. Antimicrobial testing demonstrated that BCAAs significantly enhance the antibacterial effects of lipopeptides against Escherichia coli and Staphylococcus aureus, with Val showing the most pronounced effect. The addition of BCAAs notably altered the composition of surfactin fatty acid chains. Specifically, Val increased the proportions of iso C14 and iso C16 β-hydroxy fatty acids from 13.3% and 4.216-23.803% and 8.31%, respectively. Additionally, the amino acid composition at the 7th position of the peptide chain changed significantly, especially with Val addition, which increased the proportion of C14 [Val 7] surfactin by 3.29 times. These structural changes are likely associated with the enhanced antibacterial activity of surfactin. These findings provide valuable insights into the roles of BCAAs in microbial fermentation, underscoring their importance in metabolic engineering to enhance the production of bioactive compounds.