Bioremediation Lab, School of Biosciences and Technology, VIT University, Vellore-632014, Tamil Nadu, India.
J Microbiol Biotechnol. 2013 Nov 28;23(11):1598-609. doi: 10.4014/jmb.1307.07016.
Organochlorine pesticide residues continue to remain as a major environmental threat worldwide. Lindane is an organochlorine pesticide widely used as an acaricide in medicine and agriculture. In the present study, a new lindane-degrading yeast strain, Pseudozyma VITJzN01, was identified as a copious producer of glycolipid biosurfactant. The glycolipid structure and type were elucidated by FTIR, NMR spectroscopy, and GC-MS analysis. The surface activity and stability of the glycolipid was analyzed. The glycolipids, characterized as mannosylerythritol lipids (MELs), exhibited excellent surface active properties and the surface tension of water was reduced to 29 mN/m. The glycolipid was stable over a wide range of pH, temperature, and salinity, showing a very low CMC of 25 mg/l. Bio-microemulsion of olive oil-in-water (O/W) was prepared using the purified biosurfactant without addition of any synthetic cosurfactants, for lindane solubilization and enhanced degradation assay in liquid and soil slurry. The O/W bio-microemulsions enhanced the solubility of lindane up to 40-folds. Degradation of lindane (700 mg/l) by VITJzN01 in liquid medium amended with bio-microemulsions was found to be enhanced by 36% in 2 days, compared with degradation in 12 days in the absence of bio-microemulsions. Lindane-spiked soil slurry incubated with bio-microemulsions also showed 20-40% enhanced degradation compared with the treatment with glycolipids or yeast alone. This is the first report on lindane degradation by Pseudozyma sp., and application of bio-microemulsions for enhanced lindane degradation. MEL-stabilized bio-microemulsions can serve as a potential tool for enhanced remediation of diverse lindanecontaminated environments.
有机氯农药残留仍然是全球主要的环境威胁。林丹是一种广泛用于医学和农业的有机氯农药，作为一种杀螨剂。在本研究中，鉴定了一种新型林丹降解酵母菌株，假丝酵母 VITJzN01，为丰富的糖脂生物表面活性剂产生菌。通过傅里叶变换红外光谱（FTIR）、核磁共振波谱（NMR）和气相色谱-质谱（GC-MS）分析，阐明了糖脂的结构和类型。分析了糖脂的表面活性和稳定性。糖脂的结构特征为甘露糖赤藓糖醇脂（MELs），表现出优异的表面活性，将水的表面张力降低至 29 mN/m。糖脂在宽 pH 值、温度和盐度范围内稳定，表现出非常低的 CMC（25 mg/l）。使用纯化的生物表面活性剂，无需添加任何合成助表面活性剂，制备了橄榄油-水（O/W）的生物微乳液，用于林丹的增溶和在液体和土壤悬浮液中的强化降解试验。O/W 生物微乳液将林丹的溶解度提高了 40 倍。在添加生物微乳液的液体培养基中，与不添加生物微乳液的情况下 12 天的降解相比，VITJzN01 对林丹（700 mg/l）的降解在 2 天内提高了 36%。用生物微乳液处理林丹污染的土壤悬浮液孵育也显示出比单独用糖脂或酵母处理提高 20-40%的降解。这是首次报道假丝酵母属 sp. 降解林丹，以及生物微乳液在增强林丹降解中的应用。MEL 稳定的生物微乳液可作为增强修复各种林丹污染环境的潜在工具。
