Objectives: The purpose of this study was to find the potential mechanism of two Lactobacillus (Lactobacillus plantarum L11 and Lactobacillus reuteri LR) on ameliorating obesity, including lipid metabolism and gut microbiota. The two isolates have been studied to have good characterization in vitro, but in vivo studies in modulating lipid metabolism and gut microbiota were not studied. Methods: In this study, mice with HFD supplemented with L11 or LR exhibited slower obesity progression, including reduced weight gain, abdominal fat accumulation, liver damage, inflammation, and adipose lesions. Results: Total cholesterol (TC) and triglycerides (TG) in the serum were significantly reduced (p < 0.01). The inflammatory marker interleukin-6 (IL-6) notably decreased (p < 0.05). Both Lactobacillus strains altered the gut microbiota composition, increasing the relative abundance of Alistipes and Lactobacillus, while L11 also raised Lachnospiraceae abundance. Results of the Western blot analysis showed that L11 and LR influenced the PPAR and AMPK pathways. Conclusions: L11 and LR can effectively reduce obesity by modulating gut microbiota and activating the PPAR–AMPK pathway, leading to decreased liver injury and systemic inflammation in mice fed with an HFD. In the future, the two probiotics may provide a new way for clinically ameliorating obesity on human beings.

Probiotics have been used in functional foods and dietary supplements, and in recent years, they have become more widely used in pets. In our previous experiment, Lactobacillus plantarum L-27-2 and Pediococcus lactis L-14-1 were isolated from cat feces and proved to have positive effects on lipid metabolism in mice. To further discuss their possible effects in cats, a total of 12 healthy cats (British Shorthair) were randomly divided into two groups. One group was fed Pediococcus lactis L-14-1 (1 × 10⁹ CFU/kg/d, n = 6), and the other group was fed Lactobacillus plantarum L-27-2 (1 × 10⁹ CFU/kg/d, n = 6), and the experiment was conducted for 28 days. Blood and feces were collected on days 0 and 28 separately. ELISA was used to detect blood biochemical indexes in cats. The results showed that L-27-2 and L-14-1 could reduce the content of TG (triglyceride, p < 0.05) and LDL-C (low-density lipoprotein cholesterol, p < 0.01) in the blood, increase the content of HDL-C (high-density lipoprotein, p < 0.01), and L-27-2 could significantly reduce the content of IL-6 (p < 0.01). The diversity of feces microbiota was also tested. On the phylum level, there was no significance in the phylum level of Firmicutes and Bacteroidetes (p > 0.05), but on the genus level, in the L-14-1 group, the abundance of Lantiplantibacillus and Cetobacterium was increased (p < 0.05), and the abundance of Ruminococcus, Olsenella, and Labanicoccus was decreased (p < 0.05), while in the L-27-2 group, the abundance of Libanicoccus was also decreased in L-14-1 (p < 0.05). Above all, L-27-2 and L-14-1 can be considered potential probiotics to improve cat gut health and lipid metabolism.

Lactic acid bacteria play a crucial role in maintaining the health of the host’s gut microbiota. In this study, the anti-inflammatory properties of Limosilactobacillus reuteri LR20-6 and Lacticplantibacillus plantarum L272 were evaluated using a mouse model of diarrhea induced by Escherichia coli. We also investigated their effects on gut microbiota regulation. The results indicated that both Lacticplantibacillus plantarum and Limosilactobacillus reuteri could reduce inflammation by inhibiting the expression of inflammatory factors IL-6 and TNF-α and blocking the MyD88 and NF-kB/p65 signaling pathways. Additionally, after intervention with these strains, the relative abundance of Lactobacillus was significantly increased. This suggested that Lacticplantibacillus plantarum and Limosilactobacillus reuteri could mitigate the severity of E. coli-induced diarrhea and enhance the abundance of beneficial probiotics in the gut of animals.

Yeast hydrolysate (YH) is rich in amino acids and other nutrients, and as a nutritional supplement it has been widely used in daily nutritional supplements for livestock. However, the role of YH in domestic pets, especially cats, has not yet been determined. The objective of this research was to study the effects of different concentrations of YH on the healthy cats. All cats were randomly divided into four treatments: the control group (T0, n = 6, without YH), treatment 1 (T1, the low concentration group, 0.8% of YH, n = 6), treatment 2 (T2, the middle concentration group, 1.5% of YH, n = 6), and treatment 3 (T3, the high concentration group, 4% of YH, n = 6), and the blood biochemistry, immune indexes and odorous substances in the feces, and microbiome of cats were determined on day 28. Our results showed that YH could increase the immunoglobulin G (IgG) level in the serum (p < 0.01) and reduce 3-methylindole content in the feces (p < 0.01). The acetic acid in the feces of T2 treatment (1.5%YH) was apparently increased compared to the control treatment (p < 0.05). The blood biochemistry indexes were not affected by the YH. Compared to the control group, there was no significant difference in the abundance at the phylum level. On the genus level, the abundance of g_Ruminocococcaceae and g_Lachnospiraceae, the beneficial bacteria in the gut, were decreased in the treatment T3 compared to treatment T1 (p < 0.05), but there was no significance between T1 and T2, which suggested that a high concentration of YH may be negative for gut health. So, the research showed that 1.5% of YH could be the best concentration for the improvement of immunity and gut health for cats.