混合PAHs生物降解过程中的竞争和协同作用解析

Analysis of competitive and cooperative metabolism in biodegradation of mixed PAHs

通过恒温摇床实验研究5株PAHs优良细菌对3种多环芳烃(PAHs)在单一基质和混合基质下的生物降解特征,并对优良菌降解混合PAHs时底物之间的竞争和协同代谢作用进行解析。结果表明:5株细菌对混合PAHs好氧降解效果由大到小依次为菲、蒽、芘;反应初期简单PAHs和难降解的复杂PAHs存在竞争代谢,造成短期内难降解PAHs的降解率偏低,随着反应的进行,复杂PAHs的降解率最终被提高,且对降解能力越强的菌株,这种提高作用越明显;施氏假单胞菌(Pseudomonas stutzeri sp)HY7对混合基质中的蒽、芘的降解率分别比单一基质蒽、芘的降解率提高12.7%、5.5%。

Degradation characteristics of anthracene, phenanthrene, and pyrene under the conditions of single and mixed, substrates by five PAH predominant strains were investigated through isothermal cultured experiments in a rotary shaker. The competitive and cooperative metabolism between different kinds of PAHs in the biodegradation of mixed PAHs was analyzed. The results show the following decreasing order of competitive ability： phenanthrene, anthracene, and pyrene, in the mixed culture with five predominant bacteria. There was obviously a competitive metabolism between simple PAHs and complex PAHs in the initial period of the biodegradation process, leading to a low biodegradation rate of complex PAHs. As the reaction carried on, the biodegradation rate of complex PAHs could finally be enhanced. Moreover, the greater the biodegradation capability a certain strain had, the more obvious enhancement it displayed. For Pseudomortas stutzeri sp. HY7, the biodegradation rates of anthracene and pyrene under the condition of mixed substrates could be enhanced by 12.7% and 5.5%, respectively, compared with those under the condition of a single substrate.