Lactobacillus Strains Alleviated Hyperlipidemia and Liver Steatosis in Aging Rats via Activation of AMPK.

In this study, we hypothesized that different strains of Lactobacillus can alleviate hyperlipidemia and liver steatosis via activation of 5' adenosine monophosphate-activated protein kinase (AMPK), an enzyme that is involved in cellular energy homeostasis, in aged rats. Male rats were fed with a high-fat diet (HFD) and injected with D-galactose daily over 12 weeks to induce aging. Treatments included (n = 6) (i) normal diet (ND), (ii) HFD, (iii) HFD-statin (lovastatin 2 mg/kg/day), (iv) HFD-Lactobacillus fermentum DR9 (10 log CFU/day), (v) HFD-Lactobacillus plantarum DR7 (10 log CFU/day), and (vi) HFD-Lactobacillus reuteri 8513d (10 log CFU/day). Rats administered with statin, DR9, and 8513d reduced serum total cholesterol levels after eight weeks (p < 0.05), while the administration of DR7 reduced serum triglycerides level after 12 weeks (p < 0.05) as compared to the HFD control. A more prominent effect was observed from the administration of DR7, where positive effects were observed, ranging from hepatic gene expressions to liver histology as compared to the control (p < 0.05); downregulation of hepatic lipid synthesis and ß-oxidation gene stearoyl-CoA desaturase 1 (SCD1), upregulation of hepatic sterol excretion genes of ATP-binding cassette subfamily G member 5 and 8 (ABCG5 and ABCG8), lesser degree of liver steatosis, and upregulation of hepatic energy metabolisms genes AMPKα1 and AMPKα2. Taken altogether, this study illustrated that the administration of selected Lactobacillus strains led to improved lipid profiles via activation of energy and lipid metabolisms, suggesting the potentials of Lactobacillus as a promising natural intervention for alleviation of cardiovascular and liver diseases.

Lactobacillus sp. improved microbiota and metabolite profiles of aging rats.

Aging is closely associated with altered gut function and composition, in which elderly were reported with reduced gut microbiota diversity and increased incidence of age-related diseases. Probiotics have been shown to exert beneficial health-promoting effects through modulation of intestinal microflora biodiversity, thus the effects of probiotics administration on D-galactose (D-gal) senescence-induced rat were evaluated based on the changes in gut microbiota and metabolomic profiles. Upon senescence induction, the ratio of Firmicutes/ Bacteroidetes was significantly lowered, while treatment with Lactobacillus helveticus OFS 1515 and L. fermentum DR9 increased the ratio at the phylum level (P < 0.05). Study on the genus level showed that L. paracasei OFS 0291 and L. helveticus OFS 1515 administration reduced Bacteroides, which are prominently opportunistic pathogens while L. fermentum DR9 treated rats promoted the proliferation of Lactobacillus compared to the aged rats (P < 0.05). Probiotics treatment did not alter fecal short-chain fatty acid (SCFA) profile, but an increase in acetate was observed in the D-gal rats. The analysis of fecal water-soluble metabolites showed that D-gal induced senescence caused great impact on amino acids metabolism such as urocanic acid, citrulline, cystamine and 5-oxoproline, which could serve as potential aging biomarkers. Treatment with probiotics ameliorated these metabolites in a strain-specific manner, whereby L. fermentum DR9 promoted antioxidative effect through upregulation of oxoproline, whereas both L. paracasei OFS 0291 and L. helveticus OFS 1515 restored the levels of reducing sugars, arabinose and ribose similar to the young rats. D-gal induced senescence did cause significant immunological alteration in the colon of aged rats however, all probiotic strains demonstrated immunomodulatory properties as L. paracasei OFS 0291, L. helveticus OFS 1515 and L. fermentum DR9 alleviated proinflammatory cytokines TNF-α, IFN-γ and IL-1ß as well as IL-4 compared to the aged control (P < 0.05). Our study highlights the potential of probiotics as an anti-aging therapy through healthy gut modulation.

Effects of Potential Probiotic Strains on the Fecal Microbiota and Metabolites of D-Galactose-Induced Aging Rats Fed with High-Fat Diet.

Both aging and diet play an important role in influencing the gut ecosystem. Using premature senescent rats induced by D-galactose and fed with high-fat diet, this study aims to investigate the effects of different potential probiotic strains on the dynamic changes of fecal microbiome and metabolites. In this study, male Sprague-Dawley rats were fed with high-fat diet and injected with D-galactose for 12 weeks to induce aging. The effect of Lactobacillus plantarum DR7, L. fermentum DR9, and L. reuteri 8513d administration on the fecal microbiota profile, short-chain fatty acids, and water-soluble compounds were analyzed. It was found that the administration of the selected strains altered the gut microbiota diversity and composition, even at the phylum level. The fecal short-chain fatty acid content was also higher in groups that were administered with the potential probiotic strains. Analysis of the fecal water-soluble metabolites revealed that administration of L. plantarum DR7 and L. reuteri 8513d led to higher fecal content of compounds related to amino acid metabolism such as tryptophan, leucine, tyrosine, cysteine, methionine, valine, and lysine; while administration of L. fermentum DR9 led to higher prevalence of compounds related to carbohydrate metabolism such as erythritol, xylitol, and arabitol. In conclusion, it was observed that different strains of lactobacilli can cause difference alteration in the gut microbiota and the metabolites, suggesting the urgency to explore the specific metabolic impact of specific strains on the host.

Lactic Acid Bacteria and Bifidobacteria-Inhibited Staphylococcus epidermidis.

INTRODUCTION: Lactic acid bacteria (LAB) and bifidobacteria are able to produce antimicrobial compounds to inhibit opportunisticwounding skin pathogen. The antimicrobial compounds produced are organic acids, putative bacteriocin, hydrogen peroxide, and diacetyl. Staphylococcus epidermidis is well-known as an opportunistic wounding skin pathogen in wound infections related to implanted medical devices. OBJECTIVE: To screen 87 strains of LAB and 3 strains of bifidobacteria for antimicrobial activity against Staphylococcus epidermidis.Additionally, this study sought to determine and quantify types of antimicrobial compounds produced by LAB. MATERIALS AND METHODS: Inhibitory activity of LAB and bifidobacteria on S. epidermidis was assessed with the spectrophotometric method using a 96-well microplate reader. Characterization of cell-free supernatant (CFS) was done using analytical methods. Lactobacillus fermentum (collected by the Bioprocess Department at the Universiti Sains Malaysia [BD]) 1912d, Lactobacillus casei BD 1415b, Lactobacillus fermentum BD 8313a, Pediococcus pentosaceus BD 1913b, and Weissella cibaria (collected by the Food Technology Department at the Universiti Sains Malaysia [FTDC]) 8643 with high percentage of inhibition (P < 0.05), ranging from 73.7% to 88.2%, as compared to the control, were selected for subsequent analyses. Upon neutralization, the antimicrobial activity showed a drastic drop (P < 0.05) in the percentage of inhibition. Concentrations of the inhibitive metabolites were produced in varying amounts and were strain dependent. RESULTS: Results demonstrated that lactic acid in all strains was produced in a more predominant amount than acetic acid. Protein concentration production ranged from 0.081-0.215 mg/mL. L. fermentum BD 1912d yielded as much as 0.014 mg/mL hydrogen peroxide, which was significantly higher than other strains studied. Diacetyl was produced in a higher concentration by Weissella cibaria FTDC 8643 at 2.884 ng/mL; the lowest concentration of 0.465 ng/mL was produced by Ped. pentosaceus BD 1913b. CONCLUSION: Antimicrobial metabolites from CFS of lactic acid bacteria were effective in repressing the growth of opportunistic wounding dermal pathogen Staphylococcus epidermidis.