Hudak Andrew J, Cassidy Daniel P
Department of Geosciences, Western Michigan University, Kalamazoo, Michigan 49008, USA.
Biotechnol Bioeng. 2004 Dec 30;88(7):861-8. doi: 10.1002/bit.20295.
A soil with aged contamination from lubricating oil (LO) and polychlorinated biphenyls (PCBs) was treated in a bioslurry reactor to investigate in-soil biosurfactant production by Pseudomonas aeruginosa, the most abundant indigenous, culturable, hydrocarbon-degrading microorganism. After 2 days of growth on LO, a depletion of nitrogen stimulated the production and accumulation of rhamnolipids to levels roughly 20 times the critical micelle concentration. Surface tensions and concentrations of monorhamnolipid and dirhamnolipid, PCBs, and total petroleum hydrocarbons (TPH) were measured in a slurry filtrate. Soil-bound PCBs and TPH were also quantified. Rhamnolipid production was observed within 1 to 2 days after nitrogen depletion in each of the 10 batches tested. By day 6, total rhamnolipid concentrations increased from below detection to average values over 1,000 mg/L, which caused over 98% of soil-bound PCBs and over 99% of TPH to be emulsified and recovered in the filtrate. After 70 days, rhamnolipid concentrations were only reduced by 15%, because of nitrogen-limited rates of rhamnolipid biodegradation. The results show that in-soil biosurfactant production can be stimulated in a controlled way with nutrient limitation and can be used to achieve soil washing.
在一个生物泥浆反应器中对受到润滑油（LO）和多氯联苯（PCBs）老化污染的土壤进行处理，以研究铜绿假单胞菌在土壤中生物表面活性剂的产生情况。铜绿假单胞菌是最丰富的本地可培养的烃降解微生物。在以LO为底物生长2天后，氮的消耗刺激了鼠李糖脂的产生和积累，其水平约为临界胶束浓度的20倍。在泥浆滤液中测量了表面张力、单鼠李糖脂和双鼠李糖脂、多氯联苯以及总石油烃（TPH）的浓度。还对土壤结合态的多氯联苯和总石油烃进行了定量分析。在所测试的10个批次中，每一批在氮消耗后的1至2天内都观察到了鼠李糖脂的产生。到第6天，总鼠李糖脂浓度从低于检测限增加到超过1000 mg/L的平均值，这使得超过98%的土壤结合态多氯联苯和超过99%的总石油烃被乳化并在滤液中回收。70天后，由于鼠李糖脂生物降解的氮限制速率，鼠李糖脂浓度仅降低了15%。结果表明，通过养分限制可以以可控的方式刺激土壤中生物表面活性剂的产生，并且可用于实现土壤清洗。
