新型空气分离菌 NITT6L 产生生物表面活性剂：筛选、特性分析和培养基优化。
Biosurfactant production from novel air isolate NITT6L: screening, characterization and optimization of media.
机构信息
Department of Chemical Engineering, National Institute of Technology, Tiruchirappalli, 620 015, India.
出版信息
J Microbiol Biotechnol. 2013 Sep 28;23(9):1229-43. doi: 10.4014/jmb.1212.12031.
In this paper, an air isolate (NITT6L) has been screened based on hemolytic activity, emulsification activity, drop collapsing test, and oil displacement test, as well as lipase activity. It was found that strain NITT6L was able to reduce the surface tension of the medium from 61.5 to 39.83 mN/m and could form stable emulsions with tested vegetable oils. Morphological, biochemical, 16S rRNA sequencing analyses, and fatty acid methyl ester analysis using gas chromatography confirmed that the air isolate under study was Pseudomonas aeruginosa. Characterization of the biosurfactant using agar double diffusion assay revealed that the biosurfactant was anionic in nature, and CTAB-methylene blue assay and Molisch test revealed its glycolipid nature. The FT-IR spectrum confirmed that the crude biosurfactant was a rhamnolipid. Using unoptimized medium containing sucrose as the carbon source, the isolate was found to produce 0.3 mg/ml of rhamnolipid in batch cultivation (shake flask) at 37°C and pH 7. Optimization of the medium components was carried out using design of experiments and the yield of rhamnolipid has been enhanced to 4.6 mg/ml in 72 h of fermentation.
本文从溶血活性、乳化活性、滴液崩解试验、驱油试验以及脂肪酶活性等方面筛选出一株气生菌（NITT6L）。研究发现，菌株 NITT6L 能够将培养基的表面张力从 61.5 降至 39.83 mN/m，并能与测试的植物油形成稳定的乳液。形态学、生物化学、16S rRNA 测序分析以及气相色谱法的脂肪酸甲酯分析均证实，所研究的气生菌为铜绿假单胞菌。琼脂双扩散法对生物表面活性剂的特性进行分析表明，该生物表面活性剂为阴离子型，而 CTAB-亚甲蓝试验和 Molisch 试验则揭示了其糖脂特性。傅里叶变换红外光谱（FT-IR）证实粗制生物表面活性剂为鼠李糖脂。在未优化的含有蔗糖的培养基中，该菌株在 37°C 和 pH 值为 7 的条件下进行分批培养（摇瓶），可产生 0.3 mg/ml 的鼠李糖脂。通过实验设计对培养基成分进行了优化，发酵 72 小时后，鼠李糖脂的产量提高到了 4.6 mg/ml。
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