Lysozymes are hydrolytic enzymes characterized by their ability to cleave the β-(1,4)-glycosidic bonds in peptidoglycan, a major structural component of the bacterial cell wall. This hydrolysis action compromises the integrity of the cell wall, causing the lysis of bacteria. For more than 80 years, its role of antibacterial defense in animals has been renowned, and it is also used as a preservative in foods and pharmaceuticals. In order to improve the antimicrobial efficacy of lysozyme, extensive research has been intended for its modifications. This manuscript reviews the natural antibiotic compound lysozyme with reference to its catalytic and non-catalytic mode of antibacterial action, lysozyme types, susceptibility and resistance of bacteria, modification of lysozyme molecules, and its applications in the food industry.

A short self-assembly peptide A₆K (H₂N−AAAAAAK−OH) with unmodified N− and C−terminus was designed, and the charge distribution model of this short peptide at different pH was established by computer simulation. The pH of the solution was adjusted according to the model and the corresponding self-assembled structure was observed using a transmission electron microscope (TEM). As the pH changes, the peptide will assemble into blocks or nanoribbons, which indicates that the A₆K peptide is a pH-responsive peptide. Circular dichroism (CD) and molecular dynamics (MD) simulation showed that the block structure was formed by random coils, while the increase in β-turn content contributes to the formation of intact nanoribbons. A reasonable explanation of the self-assembling structure was made according to the electrostatic distribution model and the effect of electrostatic interaction on self-assembly was investigated. This study laid the foundation for further design of nanomaterials based on pH-responsive peptides.

Selenium (Se) is an essential nutrient element in human physiological metabolism and immune function. Supplementation of bioavailable Se will confer benefit on human life, especially when intake of this nutrient is inadequate. The edible and medicinal mushroom Antrodia camphorata is a unique fungus endemic to Taiwan, which has shown high therapeutic and nutritive value. This study is the first to demonstrate that A. camphorata can assimilate and transform sodium selenite into organic selenium. With an initial concentration of Se (IV) at 10 mg/L in 100 mL of the medium at 25 °C, the total selenium content in Se-enriched A. camphorata mycelia was 1281.3 ± 79.2 µg/g, in which the organic selenium content accounted for 88.1%. Further analysis demonstrated that selenium-enriched polysaccharide was the main form of Se present in A. camphorata (61.5% of the organic selenium). Four water-soluble Se-polysaccharide fractions were separated from A. camphorata, and ACP II was the major fraction of Se-polysaccharide. The scavenging efficiency of Se-polysaccharides on DPPH and ABTS radicals was determined, proving that selenium enrichment dramatically improved the in vitro antioxidant capacity of A. camphorata polysaccharide. Therefore, the selenium accumulation and transformation ability of A. camphorata provides an opportunity for developing this beneficent fungus into a novel selenium-enriched dietary or medicinal supplement.

The site-directed immobilization of enzymes has demonstrated significant potential in industrial applications due to its ability to minimize enzyme heterogeneity and maximize retained activity. However, existing approaches often require the introduction of unnatural amino acids or excessive specific ligase to achieve this goal. In this study, a self-catalyzed protein capture system (i.e., the SnoopCatcher/SnoopTag pair) was utilized for the directed immobilization of lipase on magnetic carriers. By tagging the Pseudomonas fluorescens lipase (PFL) with a SnoopTag at the C-terminal, the fused lipase PFL-SnoopTag (PSNT) readily conjugated with the SnoopCatcher partner via a spontaneously formed isopeptide bond between them. Novel magnetic particles functionalized by SnoopCatcher proteins were prepared using a co-precipitation method, achieving a loading capacity of around 0.8 mg/g carrier for the SnoopCatcher. This functionalized magnetic carrier enabled the site-directed immobilization of lipase PSNT at 81.4% efficiency, while the enzyme loading capacity reached 3.04 mg/g carriers. To further assess the practical performance of site-directed immobilized lipases, they were applied in biodiesel production and achieved a yield of 88.5%. Our results demonstrate a universal platform for the site-directed immobilization of enzymes with high performance, which offers significant advantages, e.g., single-step purification and catalyst-free immobilization of engineered enzymes, as well as easy recovery, highlighting its potential for industrial applications.