Studies On The Mechanism Of Glycerol Monolaurate On Growth And Health Based On Microbiome And Metabolomics

Glycerol monolaurate(GML),also known as glycerol monoester of lauric acid,is naturally existed in the breast milk,coconut oil and american palm.It not only has excellent emulsification characteristics,but also has a strong ability to inhibit the growth and proliferation of bacteria,fungi and envelope virus in vitro,as well as the production of bacterial virulence factors.So far,however,there are few studies of GML in animal growth and health,and the mechanism remains unclear.Therefore,from the perspective of intestinal microbiology and metabolomics,this study used weaned piglets,fattening pigs and C57BL/6 mice as test subjects to illustrate the mechanism of GML on animal growth and health.The main results of this paper are as follows:1.150 mg/kg GML effectively improved the growth performance of weaned piglets by significantly increasing the intake and weight gain in weaned pigs compared to the positive control colistin sulfate.During the weaning period,150 mg/kg GML and colistin modulated similar changes of gut microbiota diversity and composition.However,significant differences were also observed between the GML and colistin groups that GML significantly increased the butyric acid-producing bacteria Clostridium butyricum and Blautia obeum,and decreased the two strains of probiotics Lactobacillus delbrueckii and Faecalibacterium prausnitzii.Further,GML significantly up-regulated the secretion of propionic acid and butyric acid compared to the colistin.2.During the fattening stage,feed supplementation with 150 mg/kg GML significantly improved the meat quality and safety by significantly increasing the body weight and daily weight gain in the fattening pigs,significantly enhancing the meat redness,intramuscular fat contents,serum total cholesterol and low density lipoprotein cholesterol,significantly up-regulating the intramuscular long chain fatty acids,nonessential fatty acids,arginine and tyrosine,and significantly decreasing the residues of total antibiotics and total heavy metals.3.From the perspective of gut microbiome,this study used C57BL/6 mice as test subject to illustrate the mechanism of 150 mg/kg GML on growth and health.The results demonstrated that GML significantly increased the body weight,weight gain,food intake,body fat,percentage of abdominal fat,serum triglycerides,low density lipoprotein cholesterol and atherogenic index,significantly enhanced fat droplet of abdominal fat,and significantly decreased the body muscle ratio,liver weight and high density lipoprotein cholesterol,compared to the CON group.GML significantly up-regulated the circulating levels of serum LPS and pro-inflammatory cytokines IL-1?,IL-6 and TNF-a.Meanwhile,GML significantly decreased the ?-diversity of gut microbiota and the two strains of LPS-suppressing bacteria Akkermansia muciniphila and Lupinus luteus,and significantly increased the two strains of LPS-producing bacteria Bacteroidesacidifaciens and Escherichia coli.Further,significantly up-regulated the microbial DNA abundance of the 10 predicated metabolism pathways involved in carbohydrate,amino acid and lipid metabolism.4.From the perspective of gut microbiome,the dose effect and mechanism of different doses of GML on the growth and health were investigated.The results demonstrated that within the doses of 0-150 mg/kg,the effects of GML on inducing abdominal fat accumulation,gut microbiota dysbiosis and systemic low-grade inflammation had a dose-dependent relationship in mice.High dose of 500 mg/kg GML did not have the adverse effects as dose of 500 mg/kg GML,which was highly associated with the significant increases of two strains of probiotics Lactobacillus reuteri and Ruminococcus gnavus.5.From the perspective of metabolomics,the dose effect and mechanism of GML on growth and health was studied by using UPLC-QTOF-MS.Significant differences in the metabolomics among different doses of GML groups were observed by the OPLS-DA modeling.32 biomarkers were well selected to explain the molecular mechanism on diffetent growth phenotypes induced by different doses of GML at the level of metabonomics.It was found that the increase of 2-Hydroxylauroylcarnitine was highly correlated with the reduce of fat accumulation,suggesting that 2-Hydroxylauroylcarnitine might be a compound that could reduce the body fat accumulation.