| Three categories of common root exudates,studied for their effects on the growth of the chlorpyrifos-degrading strain Cupriavidus nantongensis X1 and its biodegradability,were saccharides?fructose,glucose and sucrose?,amino acids?arginine,serine,aspartic acid,glutamic acid and cysteine acid?and organic acids?malonic acid,citric acid,succinic acid,malic acid and oxalic acid?.The results were as follows:1.Added the three saccharides to LB liquid mediums with different concentrations respectively,it was found that 20,50 and 100 mg·L-1fructose promoted the growth of strain Lux-X1 after 6 h,20 mg·L-11 glucose and 50 mg·L-11 sucrose had the same effect after 24 h.2.LB liquid mediums with five organic acids at low concentrations turned out to stimulate the growth of strain Lux-X1 in the middle-late stages.3.Five amino acids that added to LB liquid mediums showed different effects on the growth of strain Lux-X1,among which arginine worked best,followed by serine.Aspartic acid,glutamic acid and cysteine acid at the concentration of 500 mg·L-1significantly inhibited the growth of strain Lux-X1 at the early stage,which gradually receded as time went on.4.The addition of saccharides?fructose and glucose?in the basal salt medium degradation system proved to have no obvious effect on the degradation of chlorpyrifos,however,adding 100 and 200 mg·L-11 fructose increased the biomass of strain Lux-X1.5.The addition of malic acid in the basal salt medium degradation system showed no effect on the degradation of chlorpyrifos,meanwhile,malic acid,with its concentration lower than 100 mg·L-1,boosted the biomass of strain Lux-X1,likewise,there was no effect after the addition of succinic acid less than 200 mg·L-1,but that of 20 mg·L-1boosted the biomass of strain Lux-X1.6.The addition of 20 and 50 mg·L-11 cysteine for the degradation of chlorpyrifos was not found in the basal salt medium degradation system,nonetheless,the addition of cysteine advanced the degradation of TCP,a catabolite of chlorpyrifos.For serine,there were no effect on the degradation of chlorpyrifos in the basal salt medium degradation system after addition,also it had no effect on the biomass of strain Lux-X1 as the concentration lower than 100 mg·L-1.To arginine,there was little effect on the degradation by strain Lux-X1. |
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