一株分离自海水的产生物表面活性剂菌株的鉴定及其发酵优化

Identification and fermentation optimization of a biosurfactant-producing strain isolated from seawater

为研究分离白海水的芽孢杆菌dhs．330产生物表面活性剂的培养条件和产物特性，采用16SrDNA基因序列分析鉴定菌种，对发酵培养基的碳源、氮源、pH值和培养温度进行优化，采用飞行时间质谱进行产物鉴定及抑菌圈法考察产物抑菌活性。结果显示，该菌株与Bacillusmojavensis菌株16SrDNA的序列相似性为99％。菌株发酵液表面张力可由70mN·m-1降低至27mN·m-1。发酵培养基的最适碳源、有机氮源和无机氮源分别为甘油、酵母膏和尿素；pH值为6．5～7．0、温度为30-35℃条件下，菌体生长和生物表面活性剂合成最为有利。发酵产物为脂肽-糖脂混合型生物表面活性剂，对海洋污损微生物Bacilluspumilusdhs04有显著的抑菌活性。菌株dhs-330是能合成脂肽一糖脂混合生物表面活性剂、具有海洋污损微生物防除潜力的优选菌株。

This experiment studied a biosurfactant-producing bacterial strain isolated from seawa- ter, designated as dhs-330. Phylogenetic analysis of the homoeologous 16S rDNA gene se- quences, the optimization of culture conditions of carbon source, nitrogen source, pH and tem- perature, MALDI-TOF Mass Spectrometry identification of the products, and antimicrobial activi- ty assay were carried out. The 16S rDNA sequence of Bacillus sp. dhs-330 shared a 99% se- quence similarity with Bacillus mojavensis. Bacillus sp. dhs-330 decreased the surface tension of culture medium from 70 mN m-1 to 27 mN m-1. It could grow well with high production of bio- surfactants under the following conditions： glycerol as carbon source, yeast extract as organic ni- trogen source, urea as inorganic nitrogen source, initial pH 6.5-7.0 and 30-35 ℃. Its principal products were blend-biosurfactants of lipopeptide and glycolipid, which showed antimicrobial ac- tivity against marine fouling bacteria Bacillus pumilus dhs04. Strain dhs-330 presented a potential application in blend-biosurfactant production and anti-fouling technology.