The demand of biosurfactants is increasing. It is of great significance to obtain nonpathogenic and high-yielding microorganisms for the industrial-scale production of biosurfactants. A biosurfactant-producing strain SL9 was isolated from oily sludge. It was identified as Bacillus tequilensis based on colonial morphology and 16S rDNA sequence analysis. The biosurfactants produced by strain SL9 was extracted by modified acid precipitation method. A mixture of C₁₂, C₁₃, C₁₄ and C₁₅ surfactin homologues was detected based on HPLC–MS analysis. The optimum production of biosurfactants occurs at pH 7.0 and in the presence of 1.0 g/L NaCl. The optimal carbon source and nitrogen source were 40.0 g/L sucrose and 4.0 g/L NaNO₃, respectively. The maximum yield of biosurfactants from strain SL9 was up to 1332.68 mg/L. Interestingly, B. tequilensis SL9 can rapidly synthesize biosurfactants with a yield of 739.36 mg/L in 12 h. The extracted biosurfactants reduced the surface tension of water from 72.1 to 27.5 mN/m with a CMC of 33 mg/L. The biosurfactants can also emulsify paraffin with a EI₂₄ value of 57.58% and keep this good emulsifying activity after 96 h. The produced biosurfactants showed antimicrobial activities against Staphylococcus aureus, Cladosporium sp. and Alternaria sp. with inhibitory rate of 75.67%, 59.07% and 22.91%, respectively. The isolated strain B. tequilensis SL9 can be a nonpathogenic producer for rapid biosynthesis of biosurfactants with a relative high yield. Strain SL9 and its biosurfactant products are promising for application in the oil exploration, bioremediation, agricultural biocontrol, and pharmaceutical industries.

中文翻译：

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从含油污泥中分离的 Bacillus tequilensis SL9 快速生物合成生物表面活性剂：表征、优化和潜在应用

生物表面活性剂的需求不断增加。获得非致病性高产微生物对于生物表面活性剂的工业化生产具有重要意义。从含油污泥中分离得到一株生物表面活性剂生产菌株SL9。根据菌落形态和16S rDNA序列分析，鉴定为Bacillus tequilensis 。采用改良酸沉淀法提取菌株SL9产生的生物表面活性剂。基于 HPLC-MS 分析检测到C ₁₂、C ₁₃、C ₁₄和 C ₁₅表面活性素同系物的混合物。生物表面活性剂的最佳生产发生在 pH 7.0 和 1.0 g/L NaCl 存在的情况下。最佳碳源和氮源分别为40.0 g/L蔗糖和4.0 g/L NaNO ₃。菌株SL9的生物表面活性剂最大产量高达1332.68 mg/L。有趣的是，B. tequilensis SL9可以快速合成生物表面活性剂，12小时内产量可达739.36 mg/L。提取的生物表面活性剂将水的表面张力从 72.1 mN/m 降低至 27.5 mN/m，CMC 为 33 mg/L。该生物表面活性剂还可以乳化石蜡，EI ₂₄值为57.58%，并在96 h后仍保持良好的乳化活性。所生产的生物表面活性剂对金黄色葡萄球菌、枝孢菌具有抗菌活性。和链格孢属sp。抑制率分别为75.67%、59.07%和22.91%。分离的菌株B. tequilensis SL9 可以作为非致病性生产者，以相对高的产率快速生物合成生物表面活性剂。菌株SL9及其生物表面活性剂产品在石油勘探、生物修复、农业生物防治和制药行业具有广阔的应用前景。