Shanxi aged vinegar (SAV) is a famous cereal vinegar in China, which is produced through a solid-state fermentation where diverse microbes spontaneously and complex interactions occur. Here, combined with the metatranscriptomics, the microbial co-occurrence network was constructed, indicating that Lactobacillus, Acetobacter and Pediococcus are the most critical genera to maintain the fermentation stability. Based on an extensive collection of 264 relevant literatures, a transport network containing 2271 reactions between microorganisms and compounds was constructed, showing that glucose (84% of all species), fructose (67%) and maltose (67%) are the most frequently utilized substrates while lactic acid (64%), acetic acid (45%) are the most frequently occurring metabolites. Specifically, the metabolic influence of species pairs was calculated using a mathematical calculation model and the metabolic influence network was constructed. The topology properties analysis found that Lactobacillus was the key role with robust metabolic control of vinegar fermentation ecosystem and acetic acid and lactic acid were the main metabolites with feedback regulation in microbial metabolism of SAV. Furthermore, systematic coordination of positive and negative impacts was proved to be inevitable to form flavor compounds and maintain a natural microbial ecosystem. This study provides a new perspective for understanding microbial interactions in fermented food.

To investigate the structure-activity relationship of polysaccharide and obtain a better antidepressant polysaccharide, the antidepressant-like activity of a carboxymethyl polysaccharide (C-MEPS2) subjected to submerged fermentation was systematically studied. PC12-H cell and Kunming mice were used to investigate the differences and their mechanism in the antidepressant effects of C-MEPS2 and MEPS2. Cell experiments have showed that C-MEPS2 has a better antidepressant effect than MEPS2. C-MEPS2 could exert antidepressant effects related to catecholamine synthesis with specific sites of TH, D2DR, and P-CAMKII. In addition, C-MEPS2 could repair the Res-induced damage in PC12-H cell, stabilize the mitochondrial membrane potential and regulate intracellular Ca²⁺ concentration, thus reducing cell apoptosis caused by RES. Antagonists common dosing experiments on animals further proved that CMEPS2 could significantly improve the antidepressant effect of derivatives without affecting the antidepressant mechanism of MEPS2. It is speculated that it may be related to carboxymethylated modification.

Monascus vinegar (MV) is a typical fermented food with various health-promoting effects. This study aimed to evaluate the role of MV in alleviating high-fat-diet-induced inflammation in rats with hyperlipidemia and elucidate the possible regulatory mechanisms. In the study, serum lipid profiles, liver pathology and liver inflammatory cytokines were analyzed in hyperlipidemia rats with MV (0.5 mL/kg m_b, 2 mL/kg m_b). Results showed that the administration of MV alleviated dyslipidemia by decreasing the serum and liver levels of triglyceride and total cholesterol. Increase in hepatic lipase and carnitine palmitoyl transferase 1 (CPT-1) levels and decrease in hepatocyte steatosis, nephritis, and intestinal tissue injury in the HD group showed that high-dose MV can significantly suppress hepatic lipid accumulation and steatosis. In addition, compared with the model (MOD) group, the HD group showed significantly down-regulated the level of serum or hepatic alanine aminotransferase (ALT), aspartate aminotransferase (AST), CPT-1, interleukin (IL)-2, IL-6, IL-12, and tumor necrosis factor α (TNF-α). Moreover, the HD group showed repressed hepatic nuclear factor κB (NF-κB) pathway and inactivated phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway mitigated liver inflammation. Similar results were obtained from cell experiments. Collectively, these findings revealed that MV might attenuate high-fat-diet-induced inflammation by inhibiting the NF-κB and PI3K/Akt/mTOR pathways.

The entire fermentation process of traditional Chinese broad bean paste with chili comprises three individual stages: Tianbanzi, chili pei, and paste fermentation (Tianbanzi-chili pei mixture). Three stages share average 77.53% of all bacteria (89 genera), indicating that the similar environment leads to the similar bacterial communities. One, one, and three genera are exclusive to Tianbanzi, chili pei, and paste stages, respectively, due to the special physical and chemical properties for each stage. Total acidity, pH, and NaCl are important endogenous factors that promote the succession of bacterial communities. According to the dynamics of organic acids, reducing sugars, amino acids, and volatile compounds, 60-, 210-, and 180-day are considered the best fermentation periods for Tianbanzi, chili pei, and paste, respectively, to balance time cost and product quality. Three (Tetragenococcus, Lactobacillus, and Pseudomonas), four (Tetragenococcus, Lactobacillus, Bacillus, and Pseudomonas), and five (Tetragenococcus, Lactobacillus, Bacillus, Pseudomonas, and Pediococcus) genera are considered the core functional bacteria of Tianbanzi, chili pei, and paste fermentation, respectively.