Fermented feed (FF) is widely applied to improve swine performance. However, the understandings of the effects of FF on the immune status and gut microbiota of lactating sows and whether probiotics are the effective composition of FF are still limited. The present study aimed to investigate the performance, immune status and gut microbiota of lactating sows fed with a basal diet supplemented with Bacillus subtilis and Enterococcus faecium co-fermented feed (FF), with the probiotic combination (PRO) of B. subtilis and E. faecium and control diet (CON) as controls. Compared with the CON group, FF group remarkably improved the average daily feed intake of sows and the weight gain of piglets, while significantly decreased the backfat loss, constipation rate of sows and diarrhoea incidence of piglets. The yield and quality of milk of sows in FF group were improved. Besides, faecal acetate and butyrate were promoted in FF group. Additionally, FF increased the level of IgG, IgM and IL-10 and decreased the concentration of TNF-a in serum. Furthermore, FF reduced the abundance of Enterobacteriaceae and increased the level of Lactobacillus and Succiniclasticum, which were remarkably associated with growth performance and serum immune parameters. Accordingly, microbial metabolic functions including DNA repair and recombination proteins, glycolysis and gluconeogenesis, mismatch repair and D-alanine metabolism were significantly upregulated, while amino acid metabolism was downregulated in FF group. Overall, the beneficial effects of FF were superior to PRO treatment. Altogether, administration of FF during lactation improved the performance and immune status, and modulated gut microbiota of sows. Probiotics are not the only one effective compound of FF.

Fengycin is a lipopeptide with broad-spectrum antifungal activity. However, its low yield limits its commercial application. Therefore, we iteratively edited multiple target genes associated with fengycin synthesis by combinatorial metabolic engineering. The ability of Bacillus subtilis 168 to manufacture lipopeptides was restored, and the fengycin titer was 1.81 mg/L. Fengycin production was further increased to 174.63 mg/L after knocking out pathways associated with surfactin and bacillaene synthesis and replacing the native promoter (P ppsA ) with the P veg promoter. Subsequently, fengycin levels were elevated to 258.52 mg/L by upregulating the expression of relevant genes involved in the fatty acid pathway. After blocking spore and biofilm formation, fengycin production reached 302.51 mg/L. Finally, fengycin production was increased to approximately 885.37 mg/L after adding threonine in the optimized culture medium, which was 488-fold higher compared with that of the initial strain. Integrated strain engineering provides a strategy to construct a system for improving fengycin production.

The neonatal intestinal tract is immature and can be easily infected by pathogens causing inflammation. Maternal diet manipulation is a promising nutritional strategy to enhance the gut health of offspring. A fermented diet is a gut microbiota targeting diet containing live probiotics and their metabolites, which benefit the gut and overall health host. However, it remains unclear how a maternal fermented diet (MFD) affects neonatal intestinal inflammation. Here, in vivo and in vitro models together with multi-omics analysis were applied to investigate the impacts and the underlying mechanism through which an MFD prevents from gut inflammation in neonates. An MFD remarkably improved the performance of both sows and piglets and significantly altered the gut microbiome and milk metabolome of sows. In addition, the MFD significantly accelerated the maturation of the gut microbiota of neonates and increased the abundance of gut Lactobacillus and the microbial functions of amino acid-related enzymes and glucose metabolism on the weaning day. Notably, the MFD reduced susceptibility to colonic inflammation in offspring. The fecal microbiota of sows was then transplanted into mouse dams and it was found that the mouse dams and pups in the MFD group alleviated the LPS-induced decrease in gut Lactobacillus abundance and barrier injury. Milk L-glutamine (GLN) and gut Lactobacillus reuteri (LR) were found as two of the main MFD-induced sow effectors that contributed to the gut health of piglets. The properties of LR and GLN in modulating gut microbiota and alleviating colonic inflammation by inhibiting the phosphorylation of p38 and JNK and activation of Caspase 3 were further verified. These findings provide the first data revealing that an MFD drives neonate gut microbiota development and ameliorates the colonic inflammation by regulating the gut microbiota. This fundamental evidence might provide references for modulating maternal nutrition to enhance early-life gut health and prevent gut inflammation.