| In recent years,Cadmium（Cd）environmental pollution and exposure to specific occupational environments have exacerbated threats to human health.Long-term intake of Cd can cause multiple organ failure,but there is no specific treatment for Cd exposure.Therefore,there is still an urgent need to develop new drugs and strategies to eliminate Cd toxicity.Polysaccharides are important parts of food,and can effectively relieve heavy metal poisoning.In addition,biotransformation can significantly improve the biological activity of polysaccharides,which has attracted more attention of researchers.Nostoc commune Vauch.polysaccharide（NCVP）exhibits various biological activities.However,NCVP can alleviate Cd-induced injury has not been studied.Therefore,in this study,Lactobacillus were used to ferment N.Commune powder,and the effects of Lactobacillus fermentation of N.Commune on the physicochemical properties of biotransformed polysaccharide（NCVP-F）were investigated.To clarify the protective effect of Lactobacillus biotransformed NCVP-F on Cd Cl2-induced kidney injury in vitro and in vivo,and explore its potential molecular mechanism from the perspectives of cell apoptosis and gut microbiota.The main results are as follows:1.In this study,three strains of Lactobacillus were extracted from the farmer sauerkraut soup and identified by morphology,physiology and biochemistry,molecular biology:the three strains of Lactobacillus have good p H resistance,bile salt resistance and antioxidant capacity.The three strains of Lactobacillus were Lactobacillus plantarum,Lactobacillus rhamnosus and Lactobacillus plantarum and named L.rhamnosus LR1,L.plantarum LP1 and L.rhamnosus LR2 after NCBI comparison.Furthermore,the three strains of Lactobacillus did not produce extracellular polysaccharides.2.In this study,three strains of Lactobacillus were used to ferment and extract the polysaccharide from N.Commune powder,and polysaccharide was extracted by water extraction and alcohol precipitation（NCVP-F）.Compared with NCVP,the content of uronic acid,total phenols and total flavonoids of NCVP-F were significantly reduced,and the molecular weight of polysaccharide decreased from501.267 k Da to 365.369 k Da.In addition,NCVP and NCVP-F are bothα-polysaccharides,and their monosaccharide compositions are similar,but the mole percentages of mannose and glucuronic acid in NCVP-F are slightly increased.Furthermore,the ABTS and hydroxyl radical scavenging abilities of NCVP-F were slightly increased compared with NCVP.3.In this study,NCVP-F was better than NCVP in preventing Cd-induced damages on HK2 cell in vitro.In the mice model of acute Cd injury in vivo,NCVP-F also had better ability to reverse Cd-induced abnormalities of liver and kidney function,antioxidant,cytokines levels and histopathology than NCVP.Meanwhile,Western blot results indicated that NCVPs inhibited Cd-induced kidney apoptosis through the PI3K/AKT/m TOR pathway.16s r DNA results also clarified that NCVPs improve Cd-induced gut microbiota by enriching beneficial bacteria（Lachnospiraceae）and reducing harmful bacteria（Muribaculaceae,Alloprevotell and Blautia）.In addition,KEGG analysis indicated that NCVPs might improve Cd-induced abnormalities in gut microbiota by participating in different metabolic pathways.Therefore,NCVP-F shows a better effect of increasing antioxidant enzyme activity,inhibiting cytokine levels,and reducing mice kidney cells apoptosis by activating the PI3K/AKT/m TOR signaling pathway and regulating the ability of gut microbiota,thereby more effectively alleviate the injury caused by Cd in mice,which due to the reduction of molecular weight. |
