Biodegradation Of Nonionic Surfactants Represented By Triton X-100

Surfactant is a substance that can significantly reduce the interfacial tension at low concentrations.It has a wide range of applications in agriculture,medicine,daily chemical and other fields.However,the extensive use of surfactants also causes toxic and harmful substances to accumulate in the environment,causing serious ecological problems.Therefore,it is urgent to treat the surfactants in the environment and maintain the balance of the ecological environment.Based on this,this study screened the activated sludge from the aerobic aeration tank of a chemical plant’s sewage treatment plant to obtain the strain ISB5 with the ability to degrade the non-ionic surfactant Triton X-100.The degradation conditions of Triton X-100 were investigated for this strain,and after the complete genome sequencing analysis of strain ISB5,the cloning and expression of degradation genes were preliminary studied.The main results are as follows:The individual of strain ISB5 is rod-shaped or slightly curved rod-shaped,with sharp ends,no spores,no capsules,and the size of the bacteria is about1.3-2.1 μm×0.38-0.52 μm.Through sequencing and comparison analysis of the16 S r DNA of the strain,the strain ISB5 was identified as Pseudomonas sp.The conditions for strain ISB5 to degrade Triton X-100 were optimized through the combination of single factor experiment and response surface analysis.The optimized degradation conditions are as follows: culture temperature 33 ℃,initial concentration of medium Triton X-100 3.46 mg/m L,culture time 26 h,shaking rate 150 r/min,filling volume 100 m L/250 m L Erlenmeyer flask,inoculation The amount is 1%（V/V）,and the degradation rate of Triton X-100 by the strain under this condition can reach 96.21±0.4%.The whole genome sequencing analysis of the strain ISB5 showed that the whole genome length of the strain ISB5 was 5514450 bp,and the GC content was 63.36%.The genome-wide functional genes predicted 5623 functional genes（accounting for 89.01% of the total length）,22 r RNA and 75 t RNA,2CRISPR sequences and 15 gene islands.By comparing the whole genome sequence of strain ISB5 with the database,it was found that there is a gene in the genome that is most related to the degradation ability of Triton X-100,ethyl tert-butyl ether degradation protein（SAD 20）.The synthetically obtained SAD 20 gene was ligated with E.coli expression vector p ET-28a（+）to construct a recombinant plasmid p ET-28a-SAD20,and transformed into competent cells E.coli BL21 for recombinant protein expression.