Surfactin is one of the most important lipopeptide biosurfactants obtained by biocatalysts of Bacillus subtilis. The aim of this study was to isolate surfactin-producing bacilli from native soils of the country (Iran), investigate their properties, convert surfactin to surfactin micelles, determine the properties of surfactin micelles and investigate the effect of starch-coated Fe⁰ and Fe³⁺ nanoparticles on the production of surfactin from B. subtilis. To do so, 20 bacilli were isolated from the native soil sample by heat shock method and genome sequenced by SrRNA16 method. The samples with strong β-hemolysis activity were screened as surfactant-producing strains. Two species of 61 and 63 (B. subtilis subspecies. Inaquosorum) were selected and examined by quantitative and qualitative screening tests such as hemolysis activity, surfactin production, droplet aggregation, emulsifying activity, and surface tension reduction in MSM medium containing Fe⁰ and Fe³⁺ nanoparticles. Surfactin was converted to surfactin micelles by sonication and confirmed by SEM. The antimicrobial and emulsifying activity and surface tension reduction of surfactin micelles were investigated. According to the results, the surface tension reduction of surfactin micelles was greater than that of surfactin. The strain 61 (99.7%) culture in 5 L bioreactors containing Fe³⁺ nanoparticles produced more surfactin than culture of the same strain without nanoparticles. This study presents an efficient method to increase the biosynthesis of microbial metabolites.

中文翻译：

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评估伊朗天然芽孢杆菌生产脂肽生物表面活性剂和表面活性素胶束的应用范围更广

表面活性素是枯草芽孢杆菌生物催化剂得到的最重要的脂肽类生物表面活性剂之一。本研究的目的是从该国（伊朗）的本土土壤中分离产生表面活性素的杆菌，研究它们的特性，将表面活性素转化为表面活性素胶束，确定表面活性素胶束的性质，并研究淀粉包被的 Fe ⁰和 Fe的作用³⁺纳米颗粒对枯草芽孢杆菌表面活性素的产生。为此，通过热休克法从原生土壤样品中分离出 20 株杆菌，并通过 SrRNA16 法对基因组进行测序。筛选具有强β-溶血活性的样品作为表面活性剂产生菌株。61和63两种（B. subtilis 亚种。Inaquosorum ) 被选择并通过定量和定性筛选测试进行检查，例如在含有 Fe ⁰和 Fe ³⁺纳米颗粒的 MSM 介质中的溶血活性、表面活性素产生、液滴聚集、乳化活性和表面张力降低。表面活性素通过超声处理转化为表面活性素胶束，并通过扫描电镜确认。研究了表面活性素胶束的抗菌和乳化活性以及表面张力降低。根据结果​​，表面活性素胶束的表面张力降低大于表面活性素。^{菌株 61 (99.7%) 在含有 Fe 3+}的 5 L 生物反应器中培养与没有纳米颗粒的相同菌株的培养物相比，纳米颗粒产生更多的表面活性素。本研究提出了一种增加微生物代谢物生物合成的有效方法。