This study identified and sequenced 15 lysin genes from 14 novel virulent phages (10 Gram-negative and 4 Gram-positive bacterial phages). Through heterologous expression in Escherichia coli BL21(DE3), two phage lysins from Vibrio parahaemolyticus, LysCA8 and LysBA3, were obtained and purified, and two phage lysins from Bacillus cereus, LysLY1 and LysLY3, were also obtained without further purification. LysLY1 and LysLY3 had strong lytic activity against all 89 B. cereus strains tested, demonstrating a host range significantly larger than that of their parent phages (vB_BceS_LY1 and vB_BceP_LY3 were only able to lyse 3 and 2 of these B. cereus strains, respectively). LysCA8 and LysBA3 showed no lytic activity against V. parahaemolyticus in vitro, presumably due to environmental acclimation and their single-domain structure. To address this, future work should focus on structural optimization, co-expression of molecular chaperones, and chimeric enzyme design to uncover the inactivation mechanism and expand the antimicrobial spectrum of these lysins.

With global population growth and increasing environmental pressures on traditional protein sources, yeast proteins have attracted much attention as a sustainable alternative. Yeast proteins are not only nutritionally valuable and environmentally friendly, but also show broad application prospects in the food, feed and biopharmaceutical fields. The production process covers key technologies such as fermentation, cell disruption, and protein extraction and purification, and the yield and quality of yeast proteins can be significantly improved by optimizing fermentation conditions and the extraction process. Different yeast species, such as Saccharomyces cerevisiae, Candida spp., Yarrowia lipolytica and Kluyveromyces marxianus, exhibit different protein yields and qualities on a variety of substrates, providing multiple options for industrial production. In addition, the regulation of yeast protein synthesis involves multiple levels, including gene transcription, translation regulation, and nitrogen metabolism. Systems biotechnology plays an important role in identifying key synthetic genes and regulatory elements. This review summarizes recent advances in the production and application of proteins from different yeasts, as well as the regulatory mechanisms underlying yeast protein synthesis. It also gives an outlook on the important role of yeast proteins in future sustainable development. This review provides a comprehensive theoretical basis for further research and industrial application of yeast proteins.

Postbiotics are inanimate microbial cells and/or their components as well as microecological preparations made from their metabolites, which are beneficial to the health of the host. Postbiotics can regulate intestinal microbial balance, enhance immunity, and have anti-inflammatory and antibacterial effects. Compared with probiotics, living bacterial cells, postbiotics are safer, and more stable, effective and convenient. This article summarizes the origin, microbial sources, preparation methods and advantages of postbiotics, and elucidates the mechanisms of action of postbiotics in comparison with those of probiotics. In addition, it introduces readers to the applications of postbiotics as functional food supplements, food quality improvers, food preservatives and detoxifying agents in foods. We believe that as the definition, classification, and functional components of postbiotics become clearer, they will be more widely used in the fields of foods, nutraceuticals, foods for special medical purpose, infant foods, and personal care products. The development of postbiotics will also promote the leapfrog development of basic and applied science.