Lacticaseibacillus rhamnosus Fmb14 ameliorates hyperuricemia-induced hepatocyte pyroptosis via NLRP3 inflammasome cascade inhibition

Hyperuricemia is a high-risk factor for the development of gout and renal fibrosis,but the adverse effects of hyperuricemia on the liver have been seriously neglected.This research investigated the ameliorating effect of Lacticaseibacillus rhamnosus Fmb14 on hyperuricemia induced liver dysfunction both in vitro and in vivo.Cell free extracts of high dose L.rhamnosus Fmb14 treatment reduced the death rate of HepG2 cell lines from 24.1%to 14.9%by inhibiting NLRP3 recruitment,which was mainly activated by reactive oxygen species release and mitochondrial membrane potential disorder.In purine dietary induced hyperuricemia(PDIH)mice model,liver oedema and pyroptosis were ameliorated after L.rhamnosus Fmb14 administration through downregulating the expression levels of NLRP3,caspase-1 and gasdermin-D from 1.61 to 0.86,3.15 to 1.01 and 5.63 to 2.02,respectively.L.rhamnosus Fmb14 administration restored mitochondrial inner membrane protein(MPV17)and connexin 43 from 2.83 and 0.73 to 0.80 and 0.98 respectively in PDIH mice,indicating that dysbiosis of mitochondrial membrane potential was restored in liver.Intriguingly,PDIH pyroptosis stimulates the process of apoptosis,which leads to severe leakage of hepatocytes,and both of pyroptosis and apoptosis were decreased after L.rhamnosus Fmb14 treatment.Therefore,L.rhamnosus Fmb14 is a promising biological resource to maintain homeostasis of the liver in hyperuricemia and the prevention of subsequent complications.

Ameliorative effect of Lacticaseibacillus rhamnosus Fmb14 from Chinese yogurt on hyperuricemia

Hyperuricemia is a critical threat to human health,and a high inosine diet can increase the prevalence of it.Lacticaseibacillus rhamnosus Fmb14 was isolated from traditional fermented Chinese yogurt,and its inosine degradation rate reached 36.3%at 109 CFU/mL for 24 h.LC-MS analysis revealed that high concentrations of inosine could activate compensatory metabolic pathways of L.rhamnosus Fmb14 to catalyse inosine as an energy source and produce intracellular folic acid and riboflavin.The contents of folic acid and riboflavin were 6.0 and 4.3 fold increased after inosine treatment in the cell-free extracts(CFE).L.rhamnosus Fmb14 CFE treatment ameliorates hyperuricemia through xanthine oxidase(XOD)inhibition and ATP-binding cassette subfamily G member 2(ABCG2)promotion,both of which are responsible for uric acid(UA)synthesis and secretion in HepG2 and Caco2 cells,respectively.The in vivo results showed that the serum UA level decreased from 236.28 to 149.28μmol/L after 8 weeks of oral administration of L.rhamnosus Fmb14 in inosine-induced hyperuricemia model mice.Our results revealed that L.rhamnosus Fmb14 has a potential as a biological therapeutic agent in hyperuricemia prevention.

Surfactin alleviated hyperglycaemia in mice with type 2 diabetes induced by a high-fat diet and streptozotocin

Type 2 diabetes mellitus(T2DM)is associated with liver dysfunction and intestinal dysbiosis.Bioactive peptides(BAPs)have been reported to ameliorate T2DM by preventing oxidative damage to the liver.Bacillus amyloliquefaciens fmb50 produces the lipopeptide surfactin with a wide range of biological activities.The effects of surfactin on T2DM,on the other hand,have not been studied.In the present study,80 mg/kg body weight surfactin supplementation lowered fasting blood glucose(FBG)levels by 21.05%and insulin resistance(IR)by 18.18%compared with those in the T2DM group,reduced inflammation,and increased antioxidant activity in mice with T2DM induced by a high-fat diet(HFD)and streptozotocin(STZ).According to further research,surfactin administration reduced Firmicutes-to-Bacteroidetes ratios while increasing Bifi dobacterium abundance by 20 times and the level of the tight junction protein Occludin by 18.38%and ZO-1 by 66.60%.Furthermore,surfactin also improved hepatic glucose metabolism by activating the adenosine monophosphate-activated protein kinase(AMPK)signalling pathway,increasing glycogen synthesis and glucose transporter 2(GLUT2)protein expression while reducing glucose-6-phosphatase(G6Pase)protein expression.In addition,the increased Bifi dobacterium abundance indirectly reduced the liver burden of the metabolic products indole,cresol and amine produced by saprophytic bacteria.All of these findings revealed that surfactin not only ameliorated HFD/STZ-induced gut dysbiosis and preserved intestinal barrier integrity but also enhanced hepatic glucose metabolism and detoxifi cation function in T2DM mice.The gut microbiota appeared to be important in controlling glucose metabolism,IR,fat accumulation,inflammation and antioxidation,according to Spearman’s correlation coeffi cients.All data indicated that surfactin alleviated hyperglycaemia in mice with T2DM induced by HFD/STZ.

Mechanism of biofilm formation by Salmonella typhimurium ST19 in a high-glucose environment revealed by transcriptomics

Salmonella is one of the most common foodborne pathogens in the world,and Salmonella typhimurium,the most frequently isolated serotype,can cause zoonosis.In this study,we evaluated the effect of glucose concentration on the biofilm formation of 11 strains of Salmonella typhimurium.We found that among the selected strains,low-sugar conditions were more conducive to the formation of biofilms,although strain ST19 followed another rule.As the glucose concentration increased,biofilm formation showed an increasing trend.When the concentration of glucose reached 1.5%,other strains no longer formed biofilms,while strain ST19 still had strong biofilm formation ability.Therefore,we selected a culture medium containing 1.5%glucose to collect biofilms and planktonic cells of strain ST19 and compared them with strain CDC3,which did not produce a biofilm under these conditions,for transcriptomics analysis.The results showed that the related genes in the phosphotransferase system(PTS)and the operon genes regulated by AI-2 signaling molecules were highly downregulated in the biofilm bacteria of strain ST19 with a glucose content of 1.5%.At the same time,the genes involved in the two-component system,carbon metabolism and transcription regulation were significantly upregulated,which indicated that strain ST19 could adapt to a high-glucose environment by regulating glucose transport and metabolism in bacteria under a high-glucose environment and regulate biofilm formation by upregulating the expression of related genes in the two-component system.These findings illustrated that the regulated mechanism of Salmonella typhimurium's biofilm formation,which are significant to control biofilm contamination.

Deletion of COM donor and acceptor domains and the interaction between modules in bacillomycin D produced by Bacillus amyloliquefaciens

Bacillomycin D is a cyclic lipopeptide produced by Bacillus amyloliquefaciens fmbJ.At present,no relevant report has described the combinatorial biosynthesis of bacillomycin D.Due to the strong biosynthetic potential of the communication-mediating(COM)domains,its crosstalk between NRPS subunits has been studied to some extent,but the interaction of COM domain between modules is rarely reported.Therefore,in this study,we conducted the combinatorial biosynthesis of bacillomycin D through the deletion of the COM donor and acceptor domains between the modules and elucidated the interaction between the NRPS modules.The results showed that the deletion of the donor domain between modules 2 and 3 did not affect catalysis by upstream modules,but prevented downstream modules from catalysing the extension of the lipopeptide product,ultimately resulting in mutant complexes that could form linear dipeptides with the sequenceβ-NH_(2)FA-Asn-Tyr.However,the engineered hybrid bacillomycin D NRPSs lacking the donor domains between modules 3 and 4 and modules 6 and 7 could form multiple assembly lines that produced bacillomycin D and its analogs(linear tripeptides,cyclic hexapeptides and linear hexapeptides).In addition,all the acceptor domain deletion strains failed to produce bacillomycin D,only truncated peptides produced by module interruption(except for the acceptor domain deletion strains between modules 3 and 4,which also produced cyclic hexapeptides).In conclusion,deletion of the inter-module donor domains led to a more flexible hybrid biosynthetic system for the production of diverse peptide products;compared with the inter-subunit donor domain deletion strains that could only produce truncated peptides,the former had a greater biosynthetic capacity.Meanwhile,the acceptor domains between modules were an important part of module-module interactions and efficient communication within bacillomycin D synthetase.