Screening,Identification And Key Substance Analysis Of Glyphosate Degrading Bacteria

In this study,twelve strains were isolated and screened in the experimental field soil sprayed with organophosphorus pesticides.Taking the degradation rate of glyphosate as an indicator,one strain with better degradation effect was screened out from the twelve strains.Physiological and biochemical identification and 16 Sr RNA gene sequence alignment identified as Lactobacillus plantarum.The growth characteristics of the strains and the optimal culture conditions for degradation of glyphosate were studied.At the same time,intracellular enzymes,extracellular enzymes,carbohydrates,organic acids and other components were extracted to analyze the key components of glyphosate degradation.The specific research content is as follows:(1)The T6 strain with the best glyphosate degradation effect was selected from the soil of the experimental field sprayed with organophosphorus pesticides.Through the observation of colony morphology,a series of physiological and biochemical experiments and 16 Sr RNA identification,the strain T6 was determined to be Lactobacillus plantarum.(2)The growth characteristics of degrading strains were studied.The growth curve of Lactobacillus plantarum T6 showed that: 0-4 h was the growth delay period,4-18 h was the logarithmic growth period,and 18-24 h reached the growth stable period.(3)The study on the degradation characteristics of Lactobacillus plantarum T6 degrading strain showed that the ability to degrade glyphosate during 0?3 h was poor,and it was in the logarithmic growth phase at 3?18 h,reproduced faster,and degraded glyphosate efficiently.Increase;the degradation rate of glyphosate is slow in 18-24 h.(4)Determine the optimal degradation conditions of Glyphosate by Lactobacillus plantarum T6: the culture temperature is 33?,the inoculation amount is 7% and the initial glyphosate concentration is 5%.At this time,the degradation rate of Lactobacillus plantarum T6 is42.16%..(5)Extract intracellular enzymes,extracellular enzymes,polysaccharides,organic acids and other substances to study their degrading effects on glyphosate.It can be seen from the results that polysaccharides have no degrading effect on glyphosate;Organic acids have a certain effect on glyphosate degradation,but the effect is not large,concentrated in about 3.8%;the degradation rate of glyphosate by intracellular enzymes and extracellular enzymes increased first and then stabilized with the extension of fermentation time,reaching the highest point at24 h,and the degradation rate of intracellular enzymes was 3.7 %,the extracellular enzyme is36.5%.It is known that the extracellular enzyme is the key to the degradation of glyphosate.By studying the enzymatic characteristics of extracellular enzymes and the degradation characteristics of glyphosate,it can be known that the optimal temperature for degrading enzymes is 35?,p H is 7.0,and the reaction time is 92 min.At this time,the degradation rate of intracellular enzymes can reach 5.2%.The degradation rate of exoenzyme is as high as 45%,which is significantly higher than the degradation rate of Lactobacillus plantarum T6.