Microbial food is an important direction of sustainable food development in the future. Microorganisms such as Lactic acid bacteria (LAB) are important sources of natural radioprotectors. Moderate environmental stress can induce stress response and improve biological activity of LAB. In the previous study, Lactococcus lactis subsp. lactis IL1403 (L. lactis IL1403) cell-free extract induced by ionizing radiation (IR) of 500 Gy (IR-CFE) presented the stronger radioprotective effect than untreated cell-free extract in mice. To explore the radioprotective active substances of IR-CFE, the key protein was screened by proteomics and its radioprotective effect in vivo was further evaluated. The KEGG enrichment showed that two-component systems (TCS) were enhanced to adapt the IR induction. Meanwhile, the protein LlrG belonged to TCS was screened by the protein-protein interaction. Furthermore, the recombinant protein LlrG (rLlrG) could markedly alleviate the ⁶⁰Coγ-induced damage to the hematopoietic system, oxidative stress and inflammation in mice, thereby exerting its radioprotective function. These results suggested LlrG protein not only played an important role in the adaptation of L. lactis IL1403 to IR environment, but also exerted a good radioprotective effect, which could be applied in the development of protein-based radioprotectors.

Chinese yam (Dioscorea opposita Thunb.), as one of the medicinal and edible homologous plants, is rich in various nutrients and functional factors. In this study, Chinese yam fermented by Saccharomyces boulardii was performed to investigate its bioactive components and metabolic profile. And then, the main bioactive components and biological activities of fermented Chinese yam ethanol extract (FCYE) were evaluated. Results showed that there were 49 up-regulated metabolites and 52 down-regulated metabolites in fermented Chinese yam compared to unfermented Chinese yam. Besides, corresponding metabolic pathways analysis initially revealed that the distribution of bioactive substances was concentrated on alcohol-soluble small molecular substances. Ulteriorly, the total polyphenol content and the total flavonoid content in FCYE were significantly increased, and the corresponding antioxidant and immunomodulatory activities in vitro were also significantly enhanced. Our study provided a new reference for the comprehensive utilization of Chinese yam and laid a theoretical foundation for the development and application of natural probiotic-fermented products.

It is well known that exposure to environmental stresses could enhance the adaptability of bacteria and up-regulate the expression of a variety of oxidative stress-related genes and antioxidant enzymes. It is unclear whether the adaptability of microorganisms formed naturally in special environments could transfer to other organisms. The study aimed to evaluate the effects of untreated and ethanol-induced Lactococcus lactis intracellular extracts (U-IE and E-IE) on alcohol metabolism in mice. The positive effects of E-IE on alcohol metabolism in mice were revealed by the enhanced latency of loss of righting reflex (LORR), the reduced duration of LORR, the decrease of blood alcohol concentration, as well as the elevation of alcohol dehydrogenase (ADH) activities in the stomach and liver tissues. Furthermore, the potential benefits of E-IE on the liver were evaluated by biochemical parameters including the activities of serum transaminase, the levels of antioxidant enzymes, and the pathological changes of liver tissue. The present work put forward a new point that appropriate ethanol stress could enhance the intracellular ADH activity of L. lactis, and its intracellular extracts could continue to enhance alcohol metabolism in mice.

Insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) extracted from wheat bran were modified by snail enzyme and their physicochemical properties (water retention capacity and oil retention capacity), functional properties (cholesterol adsorption capacity, glucose adsorption capacity and antioxidant activity) and structural characterizations were evaluated. The results showed that snail enzyme modification led to the significant increase in oil retention capacity of IDF, glucose adsorption capacity and cholesterol adsorption capacity of IDF and SDF. Enzymatic modification also markedly improved the DPPH radical scavenging capacity and reducing power of IDF and SDF. Meanwhile, scanning electron microscopy (SEM) analysis indicated the microstructures of IDF and SDF powders were significantly changed. Fourier transfer-infrared spectrometry (FT-IR) showed that snail enzyme modification could degrade the part of cellulose and hemicellulose of IDF and SDF. All these improved physicochemical and functional properties of IDF and SDF might depend on their structural changes. It suggested that snail enzyme modification could effectively improve physicochemical and functional properties of IDF and SDF from wheat bran.