Lactiplantibacillusplantarum ATG-K2 Exerts an Anti-Obesity Effect in High-Fat Diet-Induced Obese Mice by Modulating the Gut Microbiome.

Obesity is a major health problem. Compelling evidence supports the beneficial effects of probiotics on obesity. However, the anti-obesity effect of probiotics remains unknown. In this study, we investigated the anti-obesity effects and potential mechanisms of Lactiplantibacillus plantarum ATG-K2 using 3T3-L1 adipocytes and high-fat diet (HFD)-induced obese mice. 3T3-L1 cells were incubated to determine the effect of lipid accumulation with lysate of L. plantarum ATG-K2. Mice were fed a normal fat diet or HFD with L. plantarum ATG-K2 and Orlistat for 8 weeks. L. plantarum ATG-K2 inhibited lipid accumulation in 3T3-L1 adipocytes, and reduced body weight gain, WAT weight, and adipocyte size in HFD-induced obese mice, concurrently with the downregulation of PPARγ, SREBP1c, and FAS and upregulation of PPARα, CTP1, UCP1, Prdm16, and ND5. Moreover, L. plantarum ATG-K2 decreased TG, T-CHO, leptin, and TNF-α levels in the serum, with corresponding gene expression levels in the intestine. L. plantarum ATG-K2 modulated the gut microbiome by increasing the abundance of the Lactobacillaceae family, which increased SCFA levels and branched SCFAs in the feces. L. plantarum ATG-K2 exhibited an anti-obesity effect and anti-hyperlipidemic effect in 3T3-L1 adipocytes and HFD-induced obese mice by alleviating the inflammatory response and regulating lipid metabolism, which may be influenced by modulation of the gut microbiome and its metabolites. Therefore, L. plantarum ATG-K2 can be a preventive and therapeutic agent for obesity.

Lactobacillus reuteri ATG-F4 Alleviates Chronic Stress-induced Anhedonia by Modulating the Prefrontal Serotonergic System.

Mental health is influenced by the gut-brain axis; for example, gut dysbiosis has been observed in patients with major depressive disorder (MDD). Gut microbial changes by fecal microbiota transplantation or probiotics treatment reportedly modulates depressive symptoms. However, it remains unclear how gut dysbiosis contributes to mental dysfunction, and how correction of the gut microbiota alleviates neuropsychiatric disorders. Our previous study showed that chronic consumption of Lactobacillus reuteri ATG-F4 (F4) induced neurometabolic alterations in healthy mice. Here, we investigated whether F4 exerted therapeutic effects on depressive-like behavior by influencing the central nervous system. Using chronic unpredictable stress (CUS) to induce anhedonia, a key symptom of MDD, we found that chronic F4 consumption alleviated CUS-induced anhedonic behaviors, accompanied by biochemical changes in the gut, serum, and brain. Serum and brain metabolite concentrations involved in tryptophan metabolism were regulated by CUS and F4. F4 consumption reduced the elevated levels of serotonin (5-HT) in the brain observed in the CUS group. Additionally, the increased expression of Htr1a, a subtype of the 5-HT receptor, in the medial prefrontal cortex (mPFC) of stressed mice was restored to levels observed in stress-naïve mice following F4 supplementation. We further demonstrated the role of Htr1a using AAV-shRNA to downregulate Htr1a in the mPFC of CUS mice, effectively reversing CUS-induced anhedonic behavior. Together, our findings suggest F4 as a potential therapeutic approach for relieving some depressive symptoms and highlight the involvement of the tryptophan metabolism in mitigating CUS-induced depressive-like behaviors through the action of this bacterium.

Lactobacillus plantarum HAC01 ameliorates type 2 diabetes in high-fat diet and streptozotocin-induced diabetic mice in association with modulating the gut microbiota.

Type 2 diabetes mellitus (T2DM) is a serious metabolic disorder that occurs worldwide; however, this condition can be managed with probiotics. We assessed the potential therapeutic effects of Lactobacillus plantarum HAC01 on hyperglycemia and T2DM and determined their potential mechanisms using mice with high-fat diet (HFD) and streptozotocin (STZ)-induced diabetes. The diabetic model was established with an HFD and 50 mg kg-1 STZ. L. plantarum HAC01 was then administered for 10 weeks. Body weight, food and water intake, biochemical parameters, and homeostasis model assessment for insulin resistance (HOMA-IR) were measured. Oral glucose tolerance test and histological analysis were performed, and the glucose metabolism-related gene expression and signaling pathways in the liver were determined. Fecal microbiota and serum short-chain fatty acids (SCFAs) were also analyzed. L. plantarum HAC01 significantly lowered blood glucose and HbA1c levels and improved glucose tolerance and HOMA-IR. Additionally, it increased the insulin-positive ß-cell area in islets and decreased the mRNA expression levels of phosphoenolpyruvate carboxykinase and glucose 6-phosphatase, which are associated with gluconeogenesis. L. plantarum HAC01 also increased the phosphorylation of AMPK and Akt, which are involved in glucose metabolism in the liver. Notably, L. plantarum HAC01 increased the Akkermansiaceae family and increased SCFAs in serum. L. plantarum HAC01 could alleviate hyperglycemia and T2DM by regulating glucose metabolism in the liver, protecting the islet ß-cell mass, and restoring the gut microbiota and SCFAs. L. plantarum HAC01 may thus be an effective therapeutic agent for T2DM.

Hydrolysis of Lipid-Extracted Chlorella vulgaris by Simultaneous Use of Solid and Liquid Acids.

Microalgal biomass was hydrolyzed using a solid acid catalyst with the aid of liquid acid. The use of solid acid as the main catalyst instead of liquid acid was to omit subsequent neutralization and/or desalination steps, which are commonly required in using the resulting hydrolysates for microbial fermentation. The hydrolysis of 10 g/L of lipid-extracted Chlorella vulgaris containing 12.2% carbohydrates using 7.6 g/L Amberlyst 36 and 0.0075 N nitric acid at 150°C resulted in 1.08 g/L of mono-sugars with a yield of 88.5%. For hydrolysis of higher concentrations of the biomass over 10 g/L, the amount of Amberlyst 36 needed to be increased in proportion to the biomass concentration to maintain similar levels of hydrolysis performance. Increasing the solid acid concentration protected the surface of the solid acid from being severely covered by cell debris during the reaction. A hydrolysate of lipid-extracted C. vulgaris 50 g/L was used, with no post-treatment of desalination, for the cultivation of Klebsiella oxytoca producing 2,3-butanediol. Cell growth in the hydrolysate was found to be almost the same as in the conventional medium with the same monosaccharide composition, confirming its fermentation compatibility. It was noticeable that the yield of 2,3-butanediol with the hydrolysate was observed to be 2.6 times higher than that with the conventional medium. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2729, 2019.

Production of DagA and ethanol by sequential utilization of sugars in a mixed-sugar medium simulating microalgal hydrolysate.

A novel two-step fermentation process using a mixed-sugar medium mimicking microalgal hydrolysate has been proposed to avoid glucose repression and thus to maximize substrate utilization efficiency. When DagA, a ß-agarase was produced in one step in the mixed-sugar medium by using a recombinant Streptomyces lividans, glucose was found to have negative effects on the consumption of the other sugars and DagA biosynthesis causing low substrate utilization efficiency and low DagA productivity. To overcome such difficulties, a new strategy of sequential substrate utilization was developed. In the first step, glucose was consumed by Saccharomyces cerevisiae together with galactose and mannose producing ethanol, after which DagA was produced from the remaining sugars of xylose, rhamnose and ribose. Fucose was not consumed. By adopting this two-step process, the overall substrate utilization efficiency was increased approximately 3-fold with a nearly 2-fold improvement of DagA production, let alone the additional benefit of ethanol production.

Production of 2,3-butanediol by Klebsiella oxytoca from various sugars in microalgal hydrolysate.

A new fermentation process using a mixed sugar medium is proposed in this study for 2,3-butanediol (2,3-BDO) production. The medium contained seven different monosugars known to be present in Nannochloropsis oceanica hydrolysate. The performance of each sugar when existing alone or together with glucose was evaluated. All the sugars except fucose were successfully metabolized for 2,3-BDO production. A 2,3-BDO yield of 0.31g/g was achieved with the mixed sugar medium, which was very close to that with the glucose-only medium. However, the 2,3-BDO productivity (0.28 g L(-1) h(-1) ) was found to be about 30% lower than that with glucose, implying, as expected, the existence of glucose repression on the uptake of other sugars. Strain development is in need to remove such negative effect of glucose for improved process efficiency. Fucose with the lowest uptake rate and no contribution to 2,3-BDO production can be a high value-added byproduct, once recovered and purified.

Production of DagA, a ß-agarase, by streptomyces lividans in glucose medium or mixed-sugar medium simulating microalgae hydrolysate.

DagA, a ß-agarase, was produced by cultivating a recombinant Streptomyces lividans in a glucose medium or a mixed-sugar medium simulating microalgae hydrolysate. The optimum composition of the glucose medium was identified as 25 g/l glucose, 10 g/l yeast extract, and 5 g/l MgCl2·6H2O. With this, a DagA activity of 7.26 U/ml could be obtained. When a mixedsugar medium containing 25 g/l of sugars was used, a DagA activity of 4.81 U/ml was obtained with very low substrate utilization efficiency owing to the catabolic repression of glucose against the other sugars. When glucose and galactose were removed from the medium, an unexpectedly high DagA activity of about 8.7 U/ml was obtained, even though a smaller amount of sugars was used. It is recommended for better substrate utilization and process economics that glucose and galactose be eliminated from the medium, by being consumed by some other useful applications, before the production of DagA.