2-Keto-l-gulonic acid (2-KGA), the precursor of vitamin C, is currently produced by two-step fermentation. In the second step, l-sorbose is transformed into 2-KGA by the symbiosis system composed of Ketogulonicigenium vulgare and Bacillus megaterium. Due to the different nutrient requirements and the uncertain ratio of the two strains, the symbiosis system significantly limits strain improvement and fermentation optimization. In this study, Ketogulonicigenium robustum SPU_B003 was reported for its capability to grow well independently and to produce more 2-KGA than that of K. vulgare in a mono-culture system. The complete genome of K. robustum SPU_B003 was sequenced, and the metabolic characteristics were analyzed. Compared to the four reported K. vulgare genomes, K. robustum SPU_B003 contained more tRNAs, rRNAs, NAD and NADP biosynthetic genes, as well as regulation- and cell signaling-related genes. Moreover, the amino acid biosynthesis pathways were more complete. Two species-specific internal promoters, P1 (orf_01408 promoter) and P2 (orf_02221 promoter), were predicted and validated by detecting their initiation activity. To efficiently produce 2-KGA with decreased CO2 release, an innovative acetyl-CoA biosynthetic pathway (XFP-PTA pathway) was introduced into K. robustum SPU_B003 by expressing heterologous phosphoketolase (xfp) and phosphotransacetylase (pta) initiated by internal promoters. After gene optimization, the recombinant strain K. robustum/pBBR-P1_xfp2502-P2_pta2145 enhanced acetyl-CoA approximately 2.4-fold and increased 2-KGA production by 22.27% compared to the control strain K. robustum/pBBR1MCS-2. Accordingly, the transcriptional level of the 6-phosphogluconate dehydrogenase (pgd) and pyruvate dehydrogenase genes (pdh) decreased by 24.33 ± 6.67 and 8.67 ± 5.51%, respectively. The key genes responsible for 2-KGA biosynthesis, sorbose dehydrogenase gene (sdh) and sorbosone dehydrogenase gene (sndh), were up-regulated to different degrees in the recombinant strain. The genome-based functional analysis of K. robustum SPU_B003 provided a new understanding of the specific metabolic characteristics. The new XFP-PTA pathway was an efficient route to enhance acetyl-CoA levels and to therefore promote 2-KGA production.

Probiotics are often advised to be taken separately from antibiotics due to their sensitivity to antibiotic activity and gastrointestinal (GI) stress. However, Clostridium butyricum spores, as next-generation probiotics, may withstand concurrent use with antibiotics due to their unique structural adaptations. This study systematically evaluated the survival rates and morphological changes of C. butyricum spores exposed to 10 clinically relevant antibiotics in simulated gastric/intestinal fluids, exploring their feasibility for co-administration with antibiotics. Survival rates of C. butyricum spores were tested against 10 antibiotics across four classes (β-lactams, macrolides, aminoglycosides, and tetracyclines) in simulated GI fluids. Time–kill curves analyzed spore survival over 0–4 h, while scanning electron microscopy (SEM) observed spore wall integrity and morphological changes under different conditions. The spore survival rates remained >89% in intestinal fluid and >60% in gastric fluid across all antibiotics. SEM revealed gastric acid and proteolysis increased spore wall fragmentation, reducing resistance, whereas the intestinal environment preserved spore integrity. This study was the first to demonstrate that C. butyricum spores can survive simultaneous exposure to antibiotics in the gastrointestinal tract, challenging traditional probiotic usage guidelines. The findings support their co-administration with antibiotics to simplify dosing regimens and improve medication adherence. Such an approach advances antimicrobial stewardship by optimizing therapeutic strategies for antibiotic–probiotic combinations.

Effective oral interventions for alcohol-induced metabolic stress and liver injury remain limited. Pre-absorptive gastrointestinal alcohol handling is gaining interest as a non-pharmacological strategy to reduce hepatic burden. In this study, we developed a formulation-integrated, food-compatible lyophilized recombinant whole-cell catalyst based on Escherichia coli Nissle 1917 engineered to express alcohol dehydrogenase and acetaldehyde dehydrogenase. Rather than focusing exclusively on strain-level genetic modification, the engineered cells were protected by lyophilization combined with a food-grade chitosan–alginate layer-by-layer coating, forming an artificial cell wall designed to enhance survivability during oral delivery. The formulation resisted simulated gastric acid, sodium taurocholate, and ethanol, retained enzymatic activity after storage, and demonstrated formulation stability. In alcohol-exposed mice, oral administration reduced blood ethanol and acetaldehyde levels, improved liver biochemical parameters, attenuated hepatic steatosis, and partially restored oxidative stress indicators. Integrated multi-omics analyses indicated coordinated gut-associated metabolic and inflammatory responses to alcohol and intervention, rather than a single dominant pathway. These findings provide hypothesis-generating evidence; causality remains to be established. Overall, this study demonstrates a proof-of-concept, food-compatible lyophilized recombinant whole-cell catalyst that integrates enzymatic function with formulation stability and gastrointestinal resilience, highlighting an applied, food-compatible microbial framework for exploring alcohol-related metabolic stress.

Most probiotics require separate administration from antibiotics due to sensitivity issues. Clostridium butyricum, however, exhibits intrinsic resistance, making it a promising candidate for combined therapy against diarrhea. In this study, a diarrhea model was established in mice induced by Escherichia coli, followed by treatment with azithromycin (AZM), C. butyricum (RH₂), or their combination (COM) to assess therapeutic efficacy. The results demonstrated that mice in RH₂ and COM groups achieved full body weight recovery and significant alleviation of diarrhea, accompanied by normalized fecal E. coli loads, preserved tissue integrity, reduced pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), and elevated anti-inflammatory IL-10. In contrast, AZM treatment led to sex-specific disparities in weight recovery and E. coli loads, and both sexes experienced relapse-prone diarrhea. Furthermore, the AZM group displayed shortened colons, sustained inflammatory infiltration, epithelial damage, and elevated IL-1β and male-specific IL-6. Gut microbiota analysis revealed that the COM group retained beneficial genera (e.g., Parabacteroides, Blautia) from the AZM group while uniquely enriching Lachnospiraceae taxa (e.g., NK4A136_group, FCS020_group). Untargeted metabolomics demonstrated the COM group activated GABA/arginine pathways, enhancing anti-inflammatory and barrier functions, whereas azithromycin disrupted butyrate synthesis and steroid metabolism. These findings highlight the advantage of combining C. butyricum with azithromycin for intestinal protection.

Rhizospheric fungi of medicinal plants are important sources for discovering novel and valuable secondary metabolites with potential pharmaceutical applications. In our research, five new dichlororesorcinols (1–5) and five known metabolites (6–10) were separated from the secondary metabolites of Chaetomium sp. SYP-F6997, which was isolated from the rhizospheric soil of Panax notoginseng. The identification of these compounds was confirmed using various spectroscopic techniques including ESI-MS, UV, IR, NMR and ECD analyses. These findings highlight the potential of rhizospheric fungi as a rich source of novel bioactive compounds. In addition, chiral HPLC was used to successfully separate the enantiomers compound 4 and compound 5, and TDDFT-ECD/optical rotation calculations were used to test their absolute configurations. This is the first report of compounds 1–10 from the genus Chaetomium, and the first report of compounds 1–5 and 7 from the family Chaetomiaceae. We proposed plausible biosynthetic pathways for dichlororesorcinols 1–6 based on their analogous carbon skeleton. These findings provide insights into the biosynthesis of these compounds and expand our understanding of the secondary metabolites produced by Chaetomium sp. SYP-F6997. To evaluate their potential as therapeutic agents, we investigated the cytotoxic activity of all the isolated metabolites against cell lines H9, HL-60, K562, THP-1 and CEM using the MTT method. The new compounds 1 and 2 exhibited significant cytotoxic activities against H9 and CEM, with IC50 values lower than 10 µM. To further explore the potential mechanisms of action, we performed molecular docking studies to investigate the interactions between compounds 1 and 2 with the potential target ERK2. Our results demonstrate that the compounds exhibited strong binding abilities and formed H-bond interactions with ERK2, providing support for their potent antitumor activities and promising potential as lead molecules for the development of antitumor therapeutics.