Department of Civil and Environmental Engineering, University of Auckland, 20 Symonds Street, Auckland, 1010, New Zealand.
Appl Microbiol Biotechnol. 2010 May;86(5):1563-71. doi: 10.1007/s00253-010-2453-2. Epub 2010 Feb 10.
The majority of polycyclic aromatic hydrocarbons (PAHs) sorb strongly to soil organic matter posing a complex barrier to biodegradation. Biosurfactants can increase soil-sorbed PAHs desorption, solubilisation, and dissolution into the aqueous phase, which increases the bioavailability of PAHs for microbial metabolism. In this study, biosurfactants, carbon sources, and metabolic pathway inducers were tested as stimulators of microorganism degradation. Phenanthrene served as a model PAH and Pseudomonas putida ATCC 17484 was used as the phenanthrene degrading microorganism for the liquid solutions and soil used in this investigation. Bench-scale trials demonstrated that the addition of rhamnolipid biosurfactant increases the apparent aqueous solubility of phenanthrene, and overall degradation by at least 20% when combined with salicylate or glucose in liquid solution, when compared to solutions that contained salicylate or glucose with no biosurfactant. However, salicylate addition, with no biosurfactant addition, increased the total degradation of phenanthrene 30% more than liquid systems with only biosurfactant addition. In soil slurries, small amounts of biosurfactant (0.25 g/L) showed a significant increase in total removal when only biosurfactant was added. In soil slurries containing salicylate, the effects of biosurfactant additions were negligible as there was greater than 90% removal, regardless of the biosurfactant concentration. The results of experiments performed in this study provide further evidence that an in situ enhancement strategy for phenanthrene degradation could focus on providing additional carbon substrates to induce metabolic pathway catabolic enzyme production, if degradation pathway intermediates are known.
大多数多环芳烃（PAHs）强烈吸附在土壤有机质上，形成生物降解的复杂障碍。生物表面活性剂可以增加土壤吸附的 PAHs 的解吸、增溶和溶解到水相，从而增加 PAHs 对微生物代谢的生物利用度。在这项研究中，测试了生物表面活性剂、碳源和代谢途径诱导物作为微生物降解的刺激物。菲作为一种模型 PAH，恶臭假单胞菌 ATCC 17484 被用作菲降解微生物，用于本研究中的液体溶液和土壤。台架试验表明，添加鼠李糖脂生物表面活性剂可增加菲在水中的表观溶解度，并与水杨酸盐或葡萄糖结合使用时，在液体溶液中至少可将整体降解提高 20%，与不含生物表面活性剂的水杨酸盐或葡萄糖溶液相比。然而，与仅添加生物表面活性剂的液体体系相比，添加水杨酸盐（不添加生物表面活性剂）可使菲的总降解增加 30%。在土壤悬浮液中，当仅添加生物表面活性剂时，少量生物表面活性剂（0.25 g/L）可显著增加总去除量。在含有水杨酸盐的土壤悬浮液中，添加生物表面活性剂的效果可以忽略不计，因为无论生物表面活性剂浓度如何，去除率都超过 90%。本研究中进行的实验结果进一步证明，如果已知降解途径中间产物，菲降解的原位强化策略可以集中于提供额外的碳底物来诱导代谢途径分解代谢酶的产生。
