(1) Background: Rotavirus (RV) is the primary pathogen causing diarrhea in infants and young children. The G9-type is an emerging genotype; however, its isolation is challenging, and its immunogenicity to piglets is poorly understood. This study aimed to isolate, characterize, and evaluate the immunogenicity of a PoRVA strain, RHeN2, obtained from the diarrhea samples of piglets from a pig farm in Henan Province, China. (2) Methods: Porcine rotavirus A (PoRVA) was isolated from diarrheal samples of piglets on a farm in Henan Province, China, through sequential passaging on MA-104 cells. Its immunogenicity and cross-neutralization potential were evaluated. Inactivated vaccines were prepared using two agents (formaldehyde and binary ethyleneimine, BEI) and administered intramuscularly to 28-day-old piglets. Dulbecco’s Modified Eagle Medium (DMEM) served as the control. (3) Results: A PoRVA strain, G9P[23] type, was successfully isolated and named RHeN2. Full-genome Sanger sequencing revealed the genetic constellation of this strain as G9-P[23]-I5-R1-C1- M1-A8-N1-T1-E1-H1. In addition, the titers of neutralizing antibodies peaked at 45 days post-vaccination, and the immunogenicity of the BEI-inactivated group of vaccines was better than that of the formaldehyde-inactivated group. The RHeN2 (G9P[23]) strain demonstrated a strong cross-neutralization ability against the same G9P[23] and G4P[23] strains and a stronger cross-neutralizing ability against the P[23] strains than against the P[7] strains. (4) Conclusion: The newly isolated G9P[23] strain demonstrates favorable immunogenicity, holding potential as a G9-type vaccine candidate.

Fengycin, a lipopeptide synthesized by Bacillus species, exhibits pronounced antifungal activity; however, its low production titer remains a primary constraint to broader application. Global regulatory factors constitute key actionable targets for enhancing microbial synthesis. Here, we verified the ability of Bacillus amyloliquefaciens TF28 to produce fengycin with potent inhibitory activity. Transcriptomic analysis identified five global regulators linked to fengycin biosynthesis in this strain. Following their overexpression, fermentation kinetics indicated that while these regulators generally did not affect glucose utilization, each exerted a distinct effect on cell growth and fengycin production. Specifically, degQ overexpression increased fengycin production to 116.0 mg/L, corresponding to a 23.40% increase relative to the strain without degQ overexpression, whereas overexpression of degU, sigmaH, phoP, and abrB reduced it. Moreover, degQ and abrB overexpression modulated the expression of key fengycin synthetase genes, including fenA and fenB. Collectively, these findings establish that degQ, degU, sigmaH, phoP, and abrB functionally regulate fengycin biosynthesis in B. amyloliquefaciens TF28, providing a conceptual framework for the rational design of engineered strains with enhanced fengycin productivity.

Corn stalk rot, caused by Fusarium graminearum, severely threatens corn production, while chemical fungicides lead to resistance and environmental risks. Thus, exploring environmentally friendly biocontrol agents is crucial. Though Bacillus polyketones have antifungal activity, their active components, corn stalk rot biocontrol potential and rhizosphere impacts remain unclear. This study isolated polyketones from Bacillus velezensis DJ1, assessed their antifungal activity and mechanism against F. graminearum, verified greenhouse efficacy, analyzed rhizosphere microbiota, and identified active components via HPLC-HDMS Q-TOF. The results showed that DJ1 polyketones showed dose-dependent inhibition by disrupting F. graminearum’s mycelium and membrane, with 44.33% greenhouse control efficacy. They did not disturb rhizosphere balance, only increasing Bacteroidota and DYGX01, and the active components were difficidin and bacillaene. These findings confirm DJ1 polyketones as promising eco-friendly biocontrol agents, providing a new strategy for sustainable corn stalk rot management.

Adenosine holds significant application value in the fields of food additives and pharmaceutical intermediate synthesis. Engineering strains to enhance their efficiency in utilizing fermentation substrates is considered an effective strategy for improving production yield. However, modifications to adenosine-producing strains remain challenging due to the complex physiological and metabolic regulation governing adenosine biosynthesis. In this study, the molecular regulatory mechanisms of adenosine biosynthesis in a high-yielding Bacillus subtilis strain were analyzed through transcriptome sequencing. Under conditions in which an additional 10 g/L glutamine and 6 g/L hypoxanthine were supplemented at 48 h of cultivation to promote adenosine synthesis, a total of 105 significantly differentially expressed genes (69 downregulated and 36 upregulated) were identified, with key genes related to adenosine biosynthesis primarily concentrated in the downstream purine metabolic pathway. Notably, core biosynthetic genes including purD, guaC, purH, and purN showed significant downregulation in the high-yielding strain, suggesting that adenosine accumulation might inhibit related gene expression through negative feedback mechanisms. Fermentation kinetic analysis revealed that biomass reached its peak at 48 h (OD₆₀₀ = 0.82), with a glucose consumption rate of 73.28% at this stage. Gene expression pattern analysis demonstrated that purD, guaC, purH, and purN maintained relatively stable expression levels during fermentation. However, the exogenous supplementation of inosine (6 g/L) and glutamine (10 g/L) induced significant inhibition of their expression—a trend paralleling that observed with exogenous adenosine addition. This research elucidates key regulatory nodes in the adenosine biosynthesis of Bacillus subtilis and provides theoretical support and candidate targets for the targeted modification of industrial strains through metabolic engineering strategies.