鼠李糖脂对微生物降解正十六烷以及细胞表面性质的影响

使用大庆油田石油污染土壤中分离出的优势菌种（蜡状芽孢杆菌DQ01和芽孢杆菌DQ02）,在实验室可控条件下,研究了生物表面活性剂鼠李糖脂对微生物降解正十六烷以及降解菌生长、菌体表面疏水性和外表形态的影响.结果表明,鼠李糖脂可以提高正十六烷的降解率,48 h时蜡状芽孢杆菌DQ01和芽孢杆菌DQ02对正十六烷的降解率比未加鼠李糖脂的体系分别增加了8.1％和11.6％. 正十六烷培养基中的鼠李糖脂能引起菌体表面疏水性的明显增大,且低浓度鼠李糖脂的这种能力明显优于高浓度鼠李糖脂,蜡状芽孢杆菌DQ01和芽孢杆菌DQ02分别在加入0.4 mmol/L和0.2 mmol/L鼠李糖脂时疏水性最大. 尤其是芽孢杆菌DQ02在对数生长后期BATH（bacterial adherence to hydrocarbon）达到44％,远大于未加鼠李糖脂时的BATH. 但在葡萄糖培养基中鼠李糖脂并没有明显影响菌种的生物量和BATH. 另外,加入鼠李糖脂后, 2株菌的培养基接触角比未加鼠李糖脂的培养基接触角均减小了约一半. 未加入鼠李糖脂的菌体细胞表面比较光滑,且菌体之间独立生长,而加入鼠李糖脂后影响了降解菌的外表形态,菌体细胞表面略显粗糙且相互粘连,有助于细胞与疏水性有机物的接触.

Effects of rhamnolipid on the biodegradation of n-hexadecane by microorganism and the cell surface hydrophobicity

The experiments were made in laboratory to analyze the effects of rhamnolipid on the biodegradation of n-hexadecane and the cell surface hydrophobicity using the microorganism(Bacillus cereus DQ01 and Bacillus sp.DQ02).The results show that the optimal concentrations range of rhamnolipid were 0.4(mmol/L) and 0.2(mmol/L,)respectively,which can obviously enhance BATH(bacterial adherence to hydrocarbon).The degradation of n-hexadecane by Bacillus cereus DQ01 and Bacillus sp.DQ02 were increased 8.1% and 11.6%,respectively,within 48 h in the presence of the rhamnolipid than that of in the absence of the rhamnolipid.The growth of two strains and BATH increased with obviously in the presence of the rhamnolipid.Especially BATH of Bacillus sp. DQ02 was 44% in the presence of rhamnolipid,which was better than BATH of Bacillus cereus DQ01 without rhamnolipid.In contrast,glucose experiments showed that addition of rhamnolipid did not have much impact on growth of both strains and cell surface hydrophobicity.Moreover,the interfacial tension decreased with the addition of rhamnolipid.The rhamnolipid-treated cells had a rougher texture than the untreated cell.