Production of biosurfactant by Lysinibacillus sp. and Bacillus sp. from different oils as carbon source

ABSTRACT Biosurfactants are multifunctional molecules produced by microorganisms and havea some advantages compared to synthetic surfactants, such as low toxicity, high biodegradability ,improved tensoactivity and chemical diversity. However, commercial scale production is not viable due to the high cost of the substrates used. Therefore, in the present work we evaluated the production of biosurfactants using different oils as carbon source, such as soybean oil, frying oil, diesel oil, new and used lubricating oil, from two genera of bacteria isolated from sludge cosmetics industry and soil contaminated with diesel oil, Lysinibacillus sp. and Bacillus sp. respectively. These were identified by sequencing the 16S rRNA gene fragment and kept under refrigeration at 4 ° C in test tubes with tryptone soy agar. The production was carried out under agitation at 200 rpm at 30 °C for 7 days. The biosurfactant production was analyzed by emulsifying activity, emulsification index and drop collapse. The bacteria used produced biosurfactant in all types of oils tested. Soybean oil was the best substrate for the production of biosurfactant from Lysinibacillus sp. and Bacillus sp. with an emulsification index of 50% and 46.63%, respectively.

摘要 生物表面活性剂（biosurfactants）是微生物合成的多功能分子，相较于合成表面活性剂（synthetic surfactants），其具备低毒性、高生物降解性、优异的表面活性及丰富的化学多样性等优势。但由于所用底物成本高昂，其工业化规模生产目前尚不具备可行性。因此，本研究以从化妆品工业污泥及柴油污染土壤中分离得到的两属细菌——分别为赖氨酸芽孢杆菌属（Lysinibacillus sp.）和芽孢杆菌属（Bacillus sp.）——为实验菌株，以大豆油、煎炸废油、柴油、新润滑油及废旧润滑油等不同油脂作为碳源，评估生物表面活性剂的生产效果。上述菌株通过16S rRNA基因（16S rRNA gene）片段测序完成鉴定，并以含胰蛋白胨大豆琼脂（tryptone soy agar）的试管于4℃下冷藏保藏。发酵生产在200 rpm搅拌、30℃条件下持续7天。采用乳化活性、乳化指数及落滴试验对生物表面活性剂的产生情况进行检测分析。结果表明，供试菌株在所有受试油脂中均可合成生物表面活性剂；其中大豆油为赖氨酸芽孢杆菌属和芽孢杆菌属生产生物表面活性剂的最优底物，二者对应的乳化指数分别为50%和46.63%。