Screening Of Lactobacillus Plantarum Having Three Different Organophosphorus Pesticide-Degrading Activities And Its Effect Of Detoxifying Phorate Poisoning In Rats

Organophosphorus pesticides are widely used in the field of agriculture,industry and public health.It has become a serious hidden danger of food safety because of the long term usage and overdose of organophosphorus pesticides.Pesticides cannot be eliminated completely by conventional chemical and physical pesticide elimination techniques,and these techniques easily cause secondary pollution.As recognized as safe microorganisms,lactic acid bacteria are of potential application for degradation of the pesticide in the environment,food and human body.Our current study was to screen Lactobacillus(L.)plantarum strains that had degradation activities for phorate,omethoate and dimethoate from 121 L.plantarum isolates.Among the selected strains,L.plantarum P9 had shown excellent degradation activities for phorate,omethoate and dimethoate;the degradation percentages of L.plantarum P9 for phorate,omethoate and dimethoate were 35.52±0.50%,14.00±2.97%and 11.37±1.42%,respectively.L.plantarum P9 also showed the highest tolerance to in vitro gastrointestinal juices and bile,and thus had a high potential for in vivo application.The efficacy of L.plantarum P9 by oral gavage of 5×109 cfu/d in alleviating phorate poisoning was assessed in rats.Forty-eight rats were randomly divided into four groups,namely,control group,phorate group,P9 treatment group(feeding phorate and P9 every day)and P9 prevention group(feeding P9 for 4 weeks before poisoning given phorate).The contents of phorate and its metabolites,physiological and biochemical parameters,antioxidant activity,and immune factors of blood,urine and tissues were measured to assess the efficacy of L.plantarum P9 in relieving rat poisoning.The mechanisms of P9 in alleviating phorate poisoning were revealed by conjoint analysis of gut microbiota and serum metabolome of rats.The main results were as follows.(1)The contents of phorate and its five metabolites in blood,fecal,and urine were detected.The results showed that L.plantarum P9 could improve phorate degradation in the intestine and promote the phorate excretion in rats.At the same time,the results of physiological and biochemical parameters of blood,urine and tissue showed that P9 could decrease the damage and oxdative stress of liver,kidney and brain induced by phorate.P9 also showed excellent anti-inflammatory activities,and the prophylactic application of P9 offered the strongest anti-inflammatory activity.(2)The diversity of gut microbiotia in rat feces was also detected.At the species level,phorate induced the increase of some harmful gut bacteria,such as Bacteroides massiliensis and Ruminococcus gnavus;and decrease some beneficial gut bacteria,such as Lactobacillus animalis.After P9 treatment,the harmful bacteria Butyricimonas virosa and Ruminococcus gnavus significant(P<0.05)decreased;and the probiotic short chain fatty acid-producing bacteria,Blautia coccoides,Parabacteroides goldsteinii,Alloprevotella rava,Enterorhabdus caecimuris,Parabacteroides distasoni and Lactobacillus reuteri,were significant(P<0.05)increased.These strains possibly promoted the anti-inflammatory effect of L.plantarum P9.In addition,L.plantarum P9 also increased the network complexity and stability of gut microbes in the poisoned rats.(3)The results of serum non-targeted metabolome were indicating phorate administration altered the metabolism related to the synthesis of fatty acid,unsaturated fatty acids,linoleic acid and alpha-linolenic acid,but L.plantarum P9 could rebalance these metabolic alterations.P9 could also relieve phorate poisoning of rats by regulating the metabolism of glycerophospholipid,tryptophan,aminoacyl-tRNA biosynthesis,unsaturated fatty acids and fatty acid.Overall,L.plantarum P9 could decrease phorate-induced disturbances in the serum metabolome,and some serum metabolites correlated closely with some gut bacteria.In summary,the strain L.plantarum P9 was found to possess excellent pesticide degradation activities and probiotic properties.The P9 strain could decrease the contents of phorate and its residues in rats,as well as alleviate phorate toxicity to internal organs and disturbances of the serum metabolome of poisoned rats.The regulation of rat gut microbiota by P9 seemed to be the key mechanisms of modulating the host metabolism and immunity.This thesis lays a foundation for the research of probiotics to alleviate pesticide poisoning in the body and provides theoretical support.