Zhimin Yu

Carbohydrate-binding modules (CBMs) are important substrate-binding domains that are mainly contained within carbohydrate-active enzymes. To elucidate the mechanism of enzyme-carbohydrate recognition and to promote the process of enzymatic engineering, it is important to explore more potential CBMs. However, the information and analytic tools of CBMs provided by current databases are limited. Here, a simple, user-friendly, and comprehensive CBM database (CBMDB) that integrates multidimensional information and analysis tools was constructed. Based on a data query function and analysis tools provided by the CBMDB, including sequence similarity searches, pairwise alignment, multiple sequence alignment, structure similarity searches, and phylogenetic visualization, information retrieval and analysis of known CBMs could be easily performed. Notably, unknown proteins with potential CBM functions could also be examined based on existing CBM data.

Objectives To identify a biological preservative that can protect beer from microbial contamination, which often results in the production of turbidity and off-flavor. Results The antimicrobial activity of a chitooligosaccharide against beer-spoilage bacteria and its effect on the fermentation performance of brewer’s yeast was studied. Chitooligosaccharide with an average 2 kDa molecular weight was the best at inhibiting all tested beer-spoilage bacteria. The application of chitooligosaccharide in the brewing process did not influence the fermentation of brewer’s yeast. The change in beer performance induced by the contamination of Lactobacillus brevis could be effectively controlled by application of chitooligosaccharide in the beer brewing process. Conclusion The experimental data suggested that chitooligosaccharide should be an excellent preservative to inhibit beer-spoilage bacteria in the brewing process and in the end product.

With the emergence of antibiotic-resistant strains of bacteria, the available options for treating bacterial infections have become very limited, and the search for a novel general antibacterial therapy has received much greater attention. Quorum quenching can be used to control disease in a quorum sensing system by triggering the pathogenic phenotype. The interference with the quorum sensing system by the quorum quenching enzyme is a potential strategy for replacing traditional antibiotics because the quorum quenching strategy does not aim to kill the pathogen or limit cell growth but to shut down the expression of the pathogenic gene. Quorum quenching enzymes have been identified in quorum sensing and non-quorum sensing microbes, including lactonase, acylase, oxidoreductase and paraoxonase. Lactonase is widely conserved in a range of bacterial species and has variable substrate spectra. The existence of quorum quenching enzymes in the quorum sensing microbes can attenuate their quorum sensing, leading to blocking unnecessary gene expression and pathogenic phenotypes. In this review, we discuss the physiological function of quorum quenching enzymes in bacterial infection and elucidate the enzymatic protection in quorum sensing systems for host diseases and their application in resistance against microbial diseases.