A total of 85 strains of lactic acid bacteria were isolated from corn silage in this study and analyzed in vitro for their cholesterol removal, NPC1L1 protein down-regulation and bile salt deconjugation ability, respectively. Nineteen strains were selected for further analysis for their probiotic potential. Finally, 3 strains showing better probiotic potential were evaluated for their cholesterol-lowering activity in hamsters. The strains showing the greater cholesterol removal and NPC1L1 protein down-regulation activity had no significant effects on serum and hepatic cholesterol levels in hamsters (p > 0.05). However, Lactobacillus plantarum CAAS 18008 (1 × 10⁹ CFU/d) showing the greater bile salt deconjugation ability significantly reduced serum low-density lipoprotein cholesterol, total cholesterol, and hepatic total cholesterol levels by 28.8%, 21.7%, and 30.9%, respectively (p < 0.05). The cholesterol-lowering mechanism was attributed to its bile salt hydrolase activity, which enhanced daily fecal bile acid excretion levels and thereby accelerated new bile acid synthesis from cholesterol in liver. This study demonstrated that the strains showing greater cholesterol removal and NPC1L1 protein down-regulation activity in vitro hardly reveal cholesterol-lowering activity in vivo, whereas the strains showing greater bile salt deconjugation ability in vitro has large potential to decrease serum cholesterol levels in vivo.

Hyperlipidemia poses significant risks for cardiovascular diseases, with emerging evidence underscoring the critical role of gut microbiota in metabolic regulation. This study explores Lactobacillus casei CAAS36, a probiotic strain with promising cholesterol-lowering capabilities, assessing its impact on hyperlipidemic hamsters. Utilizing 1H NMR-based metabolomics and 16S rRNA gene sequencing, we observed that L. casei CAAS36 treatment not only altered metabolic pathways but also reshaped gut microbiota composition. Notably, the treatment restored the balance between Firmicutes and Bacteroidetes and significantly increased the abundance of propionate-producing Muribaculaceae. Metabolically, L. casei CAAS36 administration led to the normalization of key lipid markers, including reductions in total cholesterol, LDL-C, and triglycerides (29.9%, 29.4% and 32.6%), while enhancing the protective HDL-C levels. These effects were accompanied by significant increases in beneficial metabolites such as propionate and succinate, which are known for their roles in preventing metabolic disorders. These findings highlight the dual regulatory effects of L. casei CAAS36 on the metabolic profile and gut microbiota, suggesting a substantial potential for this probiotic in the management of hyperlipidemia and possibly other metabolic diseases. Future applications may include its use as a natural therapeutic agent in clinical settings, aiming to reduce reliance on conventional pharmaceuticals and their associated side effects.

The study aims to analyze the composition of the gut microbiota in Chinese individuals using metagenomic sequencing technology, with a particular focus on the abundance of Akkermansia muciniphila (Akk). To improve the efficiency of Akk isolation and identification accuracy, modifications were made to the enrichment culture medium and 16S rRNA universal primers. Additionally, potential growth-promoting factors that stimulate Akk growth were explored through in vitro screening. The research results revealed that the abundance of Akk in Chinese fecal samples ranged from 0.004% to 0.4%. During optimization, a type of animal protein peptide significantly enhanced the enrichment efficiency of Akk, resulting in the isolation of three Akk strains from 14 fecal samples. Furthermore, 17 different growth-promoting factors were compared, and four factors, including galactose, sialic acid, lactose, and chitosan, were identified as significantly promoting Akk growth. Through orthogonal experiments, the optimal ratio of these four growth-promoting factors was determined to be 1:1:2:1. After adding 1.25% of this growth-promoting factor combination to the standard culture medium, Akk was cultivated at 37° for 36 h, achieving an OD_600nm value of 1.169, thus realizing efficient proliferation and optimized cultivation of Akk. This study provides important clues for a deeper understanding of the gut microbiota composition in Chinese individuals, while also offering effective methods for the isolation and cultivation of Akk, laying the groundwork for its functional and application research in the human body.

(1) Background: This study investigated the impact of in vitro adaptations to acid and bile stress on the cholesterol-lowering activity of the probiotic Lactobacillus kefir M20. (2) Methods: Lactobacillus kefir M20 was extracted from fermented dairy products in Xinjiang, China, and isolated using MRS medium. The lactic acid bacteria were cultured for stress resistance to acid and bile salts and then gavaged into mice for animal experiments. (3) Results: The adaptation to bile stress treatment resulted in a notable enhancement of the cholesterol-lowering capacity of Lactobacillus kefir M20, with reductions of 16.5% and 33.1% in total and non-HDL cholesterol, respectively, compared to the untreated strain. Furthermore, the daily fecal total bile acid excretion was 9.2, 5.4 and 5.0 times higher in the M20-BSA group compared to the HC, M20 and M20-ASA groups, respectively. (4) Conclusions: This study suggests that targeted probiotics have the potential for application in the next generation of functional foods and probiotic formulations aimed at combating hypercholesterolemia.

Naturally fermented tofu whey is a nutrient-rich byproduct of tofu production that harbors diverse lactic acid bacteria (LAB) with potential probiotic properties. However, the antioxidant mechanisms of these LAB, particularly the roles of different cellular fractions and their metabolic basis, remain unclear. This study aimed to isolate LAB from naturally fermented tofu whey and evaluate their antioxidant activities across cellular fractions, combining in vitro assays, 16S rDNA-based identification, metabolomic profiling, and cellular validation to elucidate the underlying mechanisms. Six LAB strains were isolated and screened for 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radical scavenging capacity and environmental stress tolerance. Among the identified isolates, Lactiplantibacillus plantarum MCS1903 exhibited the highest extracellular antioxidant activity. Non-targeted metabolomic analysis of cell-free supernatant revealed distinct metabolic profiles compared with the MRS control, with significant enrichment of antioxidant-related metabolites and pathways. In Caco-2 cells, MCS1903 supernatant (<5%, v/v) showed no significant cytotoxicity and effectively alleviated H₂O₂-induced oxidative stress by modulating the Nrf2/Keap1-HO-1 signaling pathway. These findings indicate that tofu whey is a valuable source of functional LAB, and MCS1903 represents a promising candidate for probiotic and functional food applications, supporting the valorization of tofu whey and development of natural antioxidant probiotics derived from fermented food byproducts.