[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.