Inactivation is a crucial step in the production of postbiotics, with thermal inactivation being the prevailing method employed. Nevertheless, the impact of thermal treatment on bioactivity and chemical composition remains unexplored. The objective of this study was to assess the influence of heating temperature on the antioxidant, anti-inflammatory properties and the chemical composition of ET-22 and BL-99 postbiotics. The findings revealed that subjecting ET-22 and BL-99 to thermal treatment ranging from 70 °C to 121 °C for a duration of 10 min effectively deactivated them, leading to the disruption of cellular structure and release of intracellular contents. The antioxidant and anti-inflammatory activity of ET-22 and BL-99 postbiotics remained unaffected by mild heating temperatures (below 100 °C). However, excessive heating at 121 °C diminished the antioxidant activity of the postbiotic. To further investigate the impact of thermal treatments on chemical composition, non-targeted metabolomics was conducted to analyze the cell-free supernatants derived from ET-22 and BL-99. The results revealed that compared to mild inactivation at temperatures below 100 °C, the excessive temperature of 121 °C significantly altered the chemical profile of the postbiotic. Several bioactive components with antioxidant and anti-inflammatory properties, including zomepirac, flumethasone, 6-hydroxyhexanoic acid, and phenyllactic acid, exhibited a significant reduction in their levels following exposure to a temperature of 121 °C. This decline in their abundance may be associated with a corresponding decrease in their antioxidant and anti-inflammatory activities. The cumulative evidence gathered strongly indicates that heating temperatures exert a discernible influence on the properties of postbiotics, whereby excessive heating leads to the degradation of heat-sensitive active constituents and subsequent diminishment of their biological efficacy.

Probiotics have gained increasing recognition for their potential to mitigate antibiotic-associated diarrhea (AAD). However, the precise mechanisms underlying their effects remain unclear. This study developed a mouse model of AAD using ceftriaxone to investigate the alleviating effects and mechanisms of Bifidobacterium animalis A6 (A6). The findings indicated that A6 supplementation effectively attenuated ceftriaxone-associated diarrhea in mice. The morphological damage to the villi and crypts was partially restored and more neatly reorganized following the A6 intervention. Additionally, intestinal morphology observations revealed a significant increase in the thickness of the mucus layer in the A6-treated group. Further examination of key regulatory genes associated with mucus secretion demonstrated that the A6 intervention effectively upregulated the expression of mucin1, thereby reinforcing the mucus layer. Concurrently, the A6 intervention upregulated the expression of the AQP4 and SLC26A3 genes in the intestine, which is responsible for restoring water absorption capacity in AAD mice. Additionally, the A6 treatment reduced ceftriaxone-induced harm to the intestinal microbiota of the mice, boosting beneficial bacteria like Bacteroidales, Akkermansia, Bifidobacterium, and Lactobacillus. Overall, this study offers valuable insights into the potential therapeutic role of A6 in restoring intestinal homeostasis and alleviating symptoms associated with AAD.

Postbiotics, as a novel class of functional components, have garnered considerable scholarly and industrial interest due to their distinctive advantages in food processing applications and their positive impact on human health. Although postbiotics have demonstrated potential in alleviating constipation, their specific mechanism of action and bioactive components remain unclear. This study aimed to investigate the ameliorative effects and potential mechanisms of postbiotics derived from Bifidobacterium animalis subsp. lactis BL-99 (BL-99) on FC using both in vivo and in vitro models. The findings revealed that both BL-99 and its postbiotics significantly mitigated FC symptoms, as evidenced by enhanced intestinal motility, and elevated fecal water content. Additionally, treatment with BL-99 postbiotics was associated with an increase in the thickness of the intestinal muscular layer and a reduction in apoptosis of intestinal smooth muscle cells (SMCs). Mechanistically, BL-99 postbiotics were found to enhance the contractile response and promote the proliferation of intestinal SMCs. Furthermore, untargeted metabolomics analysis identified two key bioactive peptides, Glu-Val and Glu-Leu, as the active components in BL-99 responsible for regulating SMC function. Collectively, these findings highlight the potential of BL-99 postbiotics as a promising functional food ingredient for alleviating FC, providing a novel and effective strategy for the developing dietary interventions targeting this condition.