A new biosurfactant was obtained from a moderately halophilic bacterium identified as Bacillus tequilensis ZSB10 that was isolated from a saline water pond located in Tehuacan-Cuicatlan valley, Mexico. A kinetic analysis of the bacterial growth of the ZSB10 strain showed a maximum growth at 24 h regardless of the initial pH (5, 7.4, and 9). The best results were found at pH = 7.4 in terms of bacterial growth, besides which the produced biosurfactant showed emulsifying and surfactant properties with an emulsification index (E₂₄) and surface tension change (ΔST) of 54 ± 0% and 26 mN m⁻¹, respectively. Extracted ZSB10 crude biosurfactant had a yield of 106 ± 6 mg L⁻¹, an E₂₄ = 58.4 ± 0.2%, and a ΔST = 26 mN m⁻¹ with a critical micelle concentration (CMC) of 44.82 mg L⁻¹. Also, its structure was characterized by MALDI-TOF mass spectrometry as a surfactin, iturin A, and fengycin mixture whose main isoform was leu/ile-7 C₁₅ surfactin [M + Na]⁺. Finally, the ZSB10 crude biosurfactant showed antifungal activity against Helminthosporium sp., with a 79.3% growth inhibition and an IC₅₀ of 1.37 mg per disc. Therefore, this biosurfactant could be used as biopesticide.

中文翻译：

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龙舌兰芽孢杆菌 ZSB10 生产生物表面活性剂：结构表征、物理化学和抗真菌特性

一种新的生物表面活性剂是从一种中等嗜盐细菌中获得的，该细菌被鉴定为龙舌兰芽孢杆菌 ZSB10，该细菌是从墨西哥 Tehuacan-Cuicatlan 山谷的一个盐水池塘中分离出来的。ZSB10 菌株细菌生长的动力学分析表明，无论初始 pH 值（5、7.4 和 9）如何，在 24 小时时都能达到最大生长。在 pH = 7.4 的细菌生长方面发现最好的结果，此外，生产的生物表面活性剂显示出乳化和表面活性剂特性，乳化指数 (E ₂₄ ) 和表面张力变化 (ΔST) 为 54 ± 0% 和 26 mN m ^{- 1}、分别。提取的 ZSB10 粗生物表面活性剂的产量为 106 ± 6 mg L ^-1，E ₂₄  = 58.4 ± 0.2%，ΔST = 26 mN m^-1具有 44.82 mg L ^-1的临界胶束浓度 (CMC) 。此外，其结构通过 MALDI-TOF 质谱法表征为表面活性素、伊图林 A 和芬霉素混合物，其主要异构体是 leu/ile-7 C _{15 表面}活性素 [M + Na] ⁺。最后，将粗ZSB10生物表面活性剂表现出抗真菌活性长蠕孢属，有79.3％的生长抑制和IC ₅₀的每张光盘1.37毫克。因此，这种生物表面活性剂可用作生物农药。