Immobilization And Proteomics Analysis Induced By DBP Of Acinetobacter Sp.LMB-5

Phthalate acid esters(PAEs)or phthalates,a class of xenobiotic organic compounds,are widely existed in various consumer products.They are widely known as the major pollutants in the environment and endocrine disruptors.Due to the weak force between PAEs and the polymeric materials,they would easily leach out into the surroundings from the plastics and pose a serious threat to the health of human and animals.A lot of experimental results show that microbial degradation is an effective way to eliminate the contaminants in the environment.However,when the free cells were used to reduce hazardous pollutants directly,loss of activity and separation from the applied conditions are the major obstacles preventing efficient treatment.The immobilized cells not only show high efficiency but also can protect them from the adverse environment.Acinetobacter sp.LMB-5 is found to be able to degrade PAEs efficiently through cometabolism.In this study,we designed an immobilized method to eliminate phthalates based on magnetic nanoparticles.The Fe3O4 nanoparticles(NPs)were synthesized by hydrothermal process and modified with 3-aminopropyltriethoxysilane.The surface-modified NPs showed a good dispersion property and the particle size was approximately 230 nm.The results showed that Acinetobacter sp.LMB-5 could be coated by the prepared magnetic particles allowing easy separation from solution by an external magnetic field.Compared to free cells,the coated cells have the same DBP reduction activity,which w-ere able to completely degrade 100 mg/L DBP in the culture after 72 h.In addition,the magnetically immobilized cells possessed adaptability to a wide range of pH and temperature,and behaved high tolerance towards toxic substances.Concerning reuseability,the magnetically coated cells retain～80 activity of DBP degradation after five cycles.By applying dimethyl-labeled quantitative proteomics,we investigated the metabolic adaptation of Acinetobacter sp.LMB-5 when exposed to DBP.The results show that more than half the total proteins,with function prediction within the genome,were identified with confidence.Among those 1716 proteins were quantifiable and 188 proteins were significantly up-regulated.Bioinformatics analysis showed that up-regulated proteins were mainly involved in acid metabolism,biodegradation of toxic substances,and stress response.The genes related to degradation of PAEs were screened according to the results of proteomics and genomics.Ten dioxygenases,14 dehydrogenases and three decarboxylases were acquired.Our study can provide theoretical basis for predicting the degradation-related enzymes.