Characteristics And Mechanism Of Degradation And Transformation Of Tris(2-chloropropyl) Phosphate By Amycolatopsis

Tris(2-chloroisopropyl)phosphate(TCPP)is a typical chlorinated organophosphorus flame retardant,which is easy to release into various environmental media and has the characteristics of strong toxicity and persistence.The microbial degradation is an important way to reduce toxic pollutants in the environment,but the microbial degradation performance and mechanism of TCPP are still to be ascertained.In view of this,Amycolatopsissp.FT-1,which can efficiently degrade TCPP isolated in the previous screening,was used as a functional strain,and the characteristics,mechanism and product toxicity of Amycolatopsissp.FT-1’s degradation and transformation of TCPP were explored.The main results of this study are as follows:(1)Amycolatopsis sp.FT-1 could effectively degrade TCPP,and the addition of co-substrates facilitated the bacterium’s degradation of TCPP,with glucose having the best enhancement effect.Four important environmental factors,namely environmental pH,temperature,glucose concentration and initial concentration of contaminant TCPP,which affect the degradation of TCPP by Amycolatopsis sp.FT-1were optimized by response surface methodology(RSM).After optimizing the factor conditions,the optimal experimental conditions for 100% degradation were obtained as: glucose dosing concentration of 6.0 g/L,temperature of 35℃,pH 6.3,and pollutant TCPP concentration of 1.1 mg/L.(2)A total of three TCPP degradation products were detected in the process of Amycolatopsis sp.FT-1 degradation of TCPP,and the transformation process of TCPP was inferred to involve mainly hydrolysis,biofenton oxidation and ketonization based on the degradation products and protein analysis.Toxicity detection of TCPP degradation mixture products by luminescent bacteria method,the results show that the toxicity of TCPP is significantly reduced after degradation by Amycolatopsis sp.FT-1.(3)TCPP is hydrolyzed by phosphoesterase to generate the corresponding diester and monoester products.In addition,TCPP is also converted by protein-mediated oxidation to corresponding diester,monoester,and ketone products,related enzymes are GMC family oxidoreductase,choline dehydrogenase,NADH-quinone oxidoreductase,glucose dehydrogenase,and lytic polysaccharide monooxygenase.(4)Organic peroxide-resistant transcriptional regulatory protein and organic hydroperoxide reductase OsmC/OhrA,alkyl hydroperoxidase,and two subunits promoting xanthine dehydrogenase production were upregulated as a defense against TCPP-induced oxidative damage.Heat shock protein 70,the ATP-dependent serine protease protein hydrolysis subunit,and elongation factor G were upregulated together to maintain protein homeostasis.In addition,up-regulation of trehalose 6-phosphate synthase,trehalose 6-phosphate phosphatase and malto-oligosyltrehalose trehalohydrolase expression promoted trehalose synthesis to eliminate peroxides generated under TCPP stress,inhibit aggregation of misfolded proteins and accelerate the clearance of denatured proteins.TetR/AcrR family transcriptional regulators and multidrug efflux transporters assist bacteria to excrete TCPP and related metabolites to maintain cell homeostasis under TCPP stress.