The interaction mechanism of BaP-Cu(II) combined pollutants on cellular interface of Stenotrophomonas maltophilia during bioremediation process

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are ubiquitous contaminants in the e-waste dismantling areas, and have become a global environmental concern because of their high toxicity and bioaccumulation through... [ view full abstract ]

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are ubiquitous contaminants in the e-waste dismantling areas, and have become a global environmental concern because of their high toxicity and bioaccumulation through food chains. Microbial remediation has been considered as a promising and economical technology for the simultaneous removal of heavy metals and PAHs combined pollutants. In our research, the biodegradation of BaP and biosorption of Cu(II) were carried out in single and combined pollution system simultaneously to discuss metabolic pathways and cellular response to combined pollutants by Stenotrophomonas maltophilia. The results indicated that BaP was broken down following the common phthalic degradation pathway when there was only BaP in the solution, while a new degradation pathway of BaP was found in Cu(II) combined system. There was more than one mechanisms behind Cu(II) removal by S. maltophilia, and the bacteria removed Cu(II) through physical/chemical interaction at first, then a part of Cu(II) changed into Cu(I) and Cu and the other part of Cu(II) adsorbed transported into bacterial cell across membrane by the P-type ATPase. However, most of Cu(II) was removed with the EPS by extracellular precipitation in the BaP-Cu(II) combined pollutant system. Cell apoptosis was observed during bioremediation process, and the intracellular ATPase activity, cell microstructure and cell membrane system were changed and damaged in a varying degree, thus, affecting the transport and removal of BaP and Cu(II). The achievements in our research provide theoretical basis and technical support for the bioremediation of PAHs and heavy metal combined pollutants.