Screening Of Lactic Acid Bacteria For Resistance To Mercury And Its Mechanism To Ameliorate Mercury Toxicity

Heavy metal pollution is dangerous,toxic and can not able biodegradable not only to damage the environment,but also a threat to the human and animal public health.Mercury is a non-essential heavy metal element in the body that can accumulate through the food chain and greatly increase the risk of damage to the body.The aim of this study is to isolate and screen mercury-resistant lactobacillus bacteria,improve the mechanism of lactic acid bacteria to extract heavy metal poisoning,and provide a new idea and theoretical basis for mercury poisoning.It will lay the foundation for future lactic acid bacteria as additives in biological preparations or animal feed.In this experiment,lactic acid bacteria with mercury tolerance were isolated from the intestinal contents of healthy animals.The isolates were screened and probabilistic tests were carried out to select probiotic strains with excellent mercury tolerance,and the resistance genes were screened.Followed by animal testing to investigate the mechanism of screening of probiotic lactobacilli by heavy metal mercury poisoning by anti-oxidative stress,cytokine detection and expression of p38 MAPK and NF-?B pathway.Below are key research findings:(1)83 strains of mercury-resistant(25 mg / L)isolates were isolated from healthy pigs,horses,cattle,sheep,dogs and chicken intestine contents.21 strains of Gram-positive bacteria with Catalase test negative,resistant acid(pH 2)and high concentrations of bile salt(0.8%)were screened.(2)Four strains were selected to inhibit the five strains of pathogenic bacteria,which were susceptible to antibiotics and had excellent antioxidant ability in vitro.The ability of the isolates to adsorb mercury is above 90%.(3)Identified by molecular biology,four strains were two strains of Lactobacillusbrevis,one Lactobacilluslucidum and one Lactobacillus johnsonii.(4)The results showed that the mercury tolerance of the strain was between 50 ~ 58 mg / L,and has different tolerance to selenium,cadmium and nickel.(5)Based on the results of the in vitro indexes,the optimal strain 23017 was screened for the resistance gene.The results showed that the similarity between the open reading frame of the resistance gene and the Aqy1 gene of lactic acid bacteria was 96% ~ 100%,which was confirmed as the aquaporin Aqy1 gene.(6)The median lethal dose of the mice was 52.69 mg / kg,and the model of acute mercury poisoning was established.Animals tested with probiotics to relieve metal mercury poisoning with the most potent strains of Lactobacillus brevis 23017.The results are as follows:a.Acute mercury poisoning can significantly reduce the weight of mice,Lactobacillus brevis23017 can effectively slow down the weight.b.Through the pathological sections showed that Lactobacillus brevis 23017 can effectively alleviate the acute mercury poisoning caused by the body's liver,kidney and intestinal damagec.Acute mercury poisoning can be formed in the liver,kidney parts accumulation,some can be excreted through the feces.Lactobacillus brevis 23017 can accelerate the discharge of mercury and reduce the burden on the liver and kidney.d.Lactobacillus brevis 23017 can accelerate the recovery of oxidative-antioxidant systems in vivo after acute mercury poisoning.e.Lactobacillus brevis 23017 can alleviate the imbalance ofproinflammatory,antiinflammatory factors and tight binding proteins caused by acute mercury poisoning.f.Acute mercury poisoning can activate p38 MAPK pathway and NF-?B pathway.Lactobacillus brevis 23017 can regulate the expression of cytokines and proteins to relieve the damage caused by inflammatory pathways.