Screening Of Probiotics For Degradation Of Organophosphorus Pesticides In Wolfberry And The Study Of Its Metabolism

The non-standard maintenance of Chinese wolfberry causes the serious diseases and pests,and the misuse of organophosphorus pesticides(OPPs).Microbial degradation is considered as one of the highest effective strategies.In present study,bioactive probiotics were screened to detoxify OPPs.Capabilities of the strains to remove pesticides were investigated and the key factors like phosphatase responsible for their degradation were then discussed.9 strains or mixtures were chosen to cultivate in medium systems spiked with 3 OPPs including chlorpyrifos(CP),DDVP and dimethoate,and 5 of them were then screened.More strongly than the other 2 OPPs,CP detoxification was enhanced by Lactobacillus plantarum and Bacillus subtilis after 96 h cultivation,resulting the increase of 45.1%and 39.6%in degradation rates respectively.Therefore,CP was chosen for follow-up studies.In the field of degradation characteristics,the tolerance to CP from L.plantarum and B.subtilis reached 1367 mg L-1 and 1283 mg L-1,respectively.In view of strains growth and CP degradation,the optimal concentration of CP was adjusted to 250 mg L-1,which led to the strongest rate constants of 0.0061 h-1 and 0.0055 h-1,respectively.With glucose of 10 g L-1 and sucrose of 5 g L-1,pH of 6.5 and 7.0,culture temperature of 37 ? and 32 ? respectively,and inoculation amount of 10%(v/v)for both,L.plantarum and B.subtilis had the best abilities to grow and degrade CP.By contrast,L.plantarum was more suitable for subsequent experiments.As to the factors governing OPPs degradation,considerable attention was paid for the enzymes.Esterase activity of L.plan.tarum was increased to 0.38 U mL-1 after 96 h fermentation,which was major influenced by the extracellular one.It was further detected and positively correlated to the measured degradation rates of CP(r = 0.951),which could be one of the key factors governing CP degradation.In addition,proposed pathways for CP degradation could be deduced that CP was hydrolyzed to TCP by combining with esterase.L.plantarum screened in lab was made into the bacteria solution and used in the field test.It also had capability to degrade CP in Chinese wolfberry,which complied the safety standards.