基于吐温-80下2株功能菌协同降解多环芳烃的特性研究

Synergistic degradation of polycyclic aromatic hydrocarbons by two functional strains in the presence of Tween-80

摘要:

【目的】研究恶臭假单胞菌B6-2和克雷伯氏菌CW-D3T构建的混合功能菌对多环芳烃的协同修复效能，并探究非离子表面活性剂吐温-80对混菌降解多环芳烃的影响，以期为芳烃化合物的生物修复提供技术参考和理论依据。【方法】通过生长曲线及平板菌落计数法反映混菌生长情况及比例，从而评估混菌降解体系的可行性；通过高效液相色谱法探究各体系以及不同吐温-80浓度下混培体系对多环芳烃的降解效能；最后通过烷烃吸附法测定细胞表面疏水性，以探究吐温-80对混合功能菌降解多环芳烃的影响机制。【结果】等比例混合的2株菌共培养生长状态优于纯培体系，对混合多环芳烃(菲、荧蒽、芘)的降解率分别为33.4%、30.1%、28.6% (7 d)，相较于菌CW-D3T，分别提高了1.31倍、1.46倍、1.42倍。混培体系中加入500 mg/L的吐温-80对菲、荧蒽、芘的降解率分别为47.7%、43.2%、38.8% (7 d)，相较于对照组各提高了1.55倍、1.38倍、1.31倍，而更高浓度的吐温-80无明显促进作用或轻微抑制。添加吐温-80使菌CW-D3T和混菌的表面疏水性提高，而菌B6-2表面疏水性降低。结合细菌生长量分析表明，更高浓度的吐温-80会对菌B6-2产生一定的毒性抑制其生长从而影响混菌降解效率。【结论】恶臭假单胞菌B6-2和克雷伯氏菌CW-D3T构建的混合功能菌具有良好的协同修复芳烃化合物效能，低浓度吐温-80可作为碳源被细菌利用，并可以提高细胞表面疏水性等从而显著提高菲、荧蒽、芘的去除效率。

Abstract:

[Objective] To study the synergistic remediation efficiency of polycyclic aromatic hydrocarbons (PAHs) by mixed functional bacteria constructed by Pseudomonas putida B6-2 and Klebsiella sp. CW-D3T, and explore the effect of non-ionic surfactant Tween-80 on the degradation of PAHs by mixed bacteria, to provide the potentials and insights for the biodegradation of aromatic compounds. [Methods] In this study, we measured the bacteria-growth curve and the determined proportion of mixed bacteria by standard plate count method, thereby exploring the feasibility of mixed bacteria degradation system. We investigated the degradation efficiencies of PAHs by pure cultures and bacterial mixed cultures at different concentrations of Tween-80 using high-performance liquid chromatography. Finally, we conducted the cell surface hydrophobicity assay by an alkane adsorption method to explore the mechanism of Tween-80 in affecting the degradation of PAHs by mixed functional bacteria. [Results] The growth state of the two strains mixed in equal proportion was better than that of the pure culture system. After 7 days, the degradation rates of mixed PAHs (phenanthrene, fluoranthene, and pyrene) were 33.4%, 30.1%, and 28.6%, respectively, which were 1.31 times, 1.46 times and 1.42 times higher than those of strain CW-D3T. The degradation rates of phenanthrene, fluoranthene, and pyrene with the addition of 500 mg/L Tween-80 to the mixed bacterial culture were 47.7%, 43.2%, and 38.8%, respectively, which were 1.55 times, 1.38 times, and 1.31 times higher than those in the control group. However, higher concentrations of Tween-80 did not significantly promote or slightly inhibit the degradation of PAHs. The addition of Tween-80 increased the surface hydrophobicity of strain CW-D3T and mixed bacteria while decreasing that of strain B6-2. Combined with the number of bacterial colonies results, the higher concentration of Tween-80 produced certain toxicity to strain B6-2 and inhibited its growth, thereby affecting the degradation efficiency of mixed bacteria. [Conclusion] The composite functional bacteria constructed by P. putida B6-2 and Klebsiella sp. CW-D3T has a good efficiency in degrading aromatic compounds. A low concentration of Tween-80 can be utilized as a carbon source and change the hydrophobicity of the cell surface, thus significantly improving the removal efficiency of phenanthrene, fluoranthene and pyrene.