The potential of the gut microbiome as a driver of individual cognitive differences in natural populations of animals remains unexplored. Here, using metagenomic sequencing of individual bumblebee hindguts, we find a positive correlation between the abundance of Lactobacillus Firm-5 cluster and memory retention on a visual discrimination task. Supplementation with the Firm-5 species Lactobacillus apis, but not other non-Firm-5 bacterial species, enhances bees’ memory. Untargeted metabolomics after L. apis supplementation show increased LPA (14:0) glycerophospholipid in the haemolymph. Oral administration of the LPA increases long-term memory significantly. Based on our findings and metagenomic/metabolomic analyses, we propose a molecular pathway for this gut-brain interaction. Our results provide insights into proximate and ultimate causes of cognitive differences in natural bumblebee populations.

Pulsed electric field (PEF) is an innovative, non-thermal technology for food preservation with many superiorities. However, the sub-lethally injured microorganisms caused by PEF and their recovery provide serious food safety problems. Our study examined the effects of pH, temperature and natural preservatives (tea polyphenols and natamycin) on the recovery of PEF-induced, sub-lethally injured Saccharomyces cerevisiae cells, and further explored the bactericidal effects of the combined treatments of PEF with the pivotal factors in cantaloupe juice. We first found that low pH (pH 4.0), low temperature (4 °C), tea polyphenols and natamycin inhibited the recovery of injured S. cerevisiae cells. Then, the synergistic effects of PEF, combined with cold-temperature storage (4 °C), a mild treatment temperature (50 and 55 °C), tea polyphenols or natamycin, on the inactivation of S. cerevisiae in cantaloupe juice were evaluated. Our results showed that the combination of PEF and heat treatment, tea polyphenols or natamycin enhanced the inactivation of S. cerevisiae and reduced the level of sub-lethally injured cells. Moreover, PEF combined with 55 °C heat treatment or tea polyphenols was applied for cantaloupe juice. In the practical application, the two combined PEF methods displayed a comparable inactivation heat pasteurization ability, prolonged the shelf life of juice compared with PEF treatment alone, and better preserved the physicochemical properties and vitamin C levels of cantaloupe juice. These results provide valuable information to inhibit the recovery of PEF-injured microbial cells and shed light on the combination of PEF with other factors to inactivate microorganisms for better food preservation.

Although many efforts have been made to characterize the functional properties of flaxseed, knowledge concerning the properties of insoluble and soluble dietary fibers in flaxseed is still limited. Here, insoluble and soluble dietary fibers were extracted from flaxseed cake—a valuable resource that has not been fully exploited. Subsequently, their monosaccharide compositions, structural properties, and anti-obesity effects in male mice were characterized. The anti-obesity effects of flaxseed cake insoluble dietary fiber (FIDF), flaxseed cake soluble dietary fiber (FSDF), and FIDF combined with FSDF in diet-induced obese mice were investigated in our study. Supplementation with FSDF alone or FIDF and FSDF together lowered the fat accumulation, improved the serum lipid profile, increased the basal metabolism, and improved the gut microbiota of obese mice. Supplementation with FIDF and FSDF together significantly enriched the abundance of g_Akkermansia and g_Bifidobacterium, which are negatively associated with obesity. Supplementation with FIDF alone improved the liver lipid profile, raised the basal metabolism, and enhanced the short-chain fatty acid levels in the guts of the mice. In conclusion, our results collectively support the therapeutic potential of FIDF and FSDF in obesity treatment and indicate that FIDF and FSDF play different roles in the process of obesity treatment. Furthermore, our results provide critical information for flaxseed cake resource exploitation.

Background: Dietary fibre can alleviate or reduce the risk of obesity and obesity-induced abnormalities in glycolipid metabolism. However, the effects of different types of dietary fibre or their combinations on obesity remain unclear. Here, we explored the effects of different ratios of inulin soluble dietary fibre (ISDF) and barley leaf insoluble dietary fibre (BLIDF) on the body weight, glycolipid metabolism and gut microbiota of obese mice. Methods: Seven experimental groups were treated with different combinations of soluble and insoluble fibre, comprising HFD (high-fat diet without dietary fibre), BLIDF, ISDF, I3S1DF (insoluble/soluble = 3:1), I2S2DF (insoluble/soluble = 1:1), I1S3DF (insoluble/soluble = 1:3) and MIX (inulin, BLIDF and matcha powder fibre; insoluble/soluble = 3.6:1) groups. Results: Our results showed that the BLIDF, ISDF and MIX treatments decreased the body weight gain of the HFD mice significantly after eight-week interventions. All the fibre intervention groups except the MIX group displayed lower fasting blood glucose and glycosylated serum protein levels than the HFD group. BLIDF, ISDF, I3S1DF and I2S2DF improved the glucose tolerance of the mice. Moreover, none of the dietary fibre interventions affected the liver lipid metabolism, while I3S1DF and I1S3DF improved the abnormal serum lipid metabolism. BLIDF, ISDF, I3S1DF and I2S2DF reduced the serum IL-6 levels, and BLIDF and I1S3DF increased SOD activity significantly. Additionally, all the dietary fibre interventions decreased the Firmicutes to Bacteroidota (F/B) ratio and increased the abundance of beneficial gut microbes differently. Conclusions: In short, our results suggest that different ratios of soluble and insoluble dietary fibre have unique impacts on mice body weight, glycolipid metabolism, inflammation and gut microbiota. The ratio of soluble to insoluble dietary fibre intake should be considered for specific health goals in the future.