Innovating glycoside hydrolase activity on a same structural scaffold

Bioprinting of transparent and adhesive corneal patches: Integrating photo-crosslinkable dopamine-conjugated silk fibroin and decellularized cornea matrix for sutureless tissue integration and regeneration

Corneal injuries, a leading cause of visual impairment, are traditionally addressed through tissue transplantation. However, challenges such as donor shortages, graft rejection, and complications from suturing often limit their effectiveness. Current corneal adhesives frequently fall short in both adhesion strength and biocompatibility. We present an innovative solution: a photocurable hydrogel that integrates dopamine-conjugated methacrylated silk fibroin (d-MSF) with a decellularized corneal matrix (DCM). This hydrogel combines advanced materials to create a bioadhesive system that offers superior adhesion inspired by mussel adhesion and mimics the native tissue environment. FTIR and NMR analyses confirm that our conjugation process prevents unwanted beta-sheet aggregation, ensuring both stability and transparency. The hydrogel demonstrates excellent rheological properties, including enhanced shear-thinning and impressive shear and creep recovery, making it highly suitable for extrusion-based bioprinting. We successfully bioprinted a bilayer corneal patch, featuring a concentric ring of d-MSF as the first layer, overlaid with a second layer of DCM. The implants exhibit strong tissue adhesion, with an adhesion strength of 85 ± 5.6 KPa, and Young's modulus of 0.48 ± 0.064 MPa, ensuring excellent structural integrity. This results in a highly transparent (>80 %) and functional adhesive corneal patch. This advancement offers a promising, biocompatible alternative to traditional keratoprostheses, advancing corneal repair technology.

Biosafety consideration of nanocellulose in biomedical applications: A review

Nanocellulose-based biomaterials have gained significant attention in various fields, especially in medical and pharmaceutical areas, due to their unique properties, including non-toxicity, high specific surface area, biodegradability, biocompatibility, and abundant feasible and sophisticated strategies for functional modification. The biosafety of nanocellulose itself is a prerequisite to ensure the safe and effective application of biomaterials as they interact with living cells, tissues, and organs at the nanoscale. Potential residual endogenous impurities and exogenous contaminants could lead to the failure of the intended functionalities or even serious health complications if they are not adequately removed and assessed before use. This review summarizes the sources of impurities in nanocellulose that may pose potential hazards to their biosafety, including endogenous impurities that co-exist in the cellulosic raw materials themselves and exogenous contaminants caused by external exposure. Strategies to reduce or completely remove these impurities are outlined and classified as chemical, physical, biological, and combined methods. Additionally, key points that require careful consideration in the interpretation of the biosafety evaluation outcomes were discussed to ensure the safety and effectiveness of the nanocellulose-based biomaterials in medical applications.

Oregano Essential Oils Promote Rumen Digestive Ability by Modulating Epithelial Development and Microbiota Composition in Beef Cattle

This study aimed to explore the effects of oregano essential oils (OEO) on the rumen digestive ability using multi-omics sequencing techniques. Twenty-seven castrated Pingliang red cattle were randomly separated into three groups (3 cattle/pen; n = 9) and fed on a daily basal diet supplemented with 0 (Con group), 130 mg (L group), and 260 mg (H group) OEO. The finishing trial lasted for 390 days, and all cattle were slaughtered to collect rumen tissue and content samples. We found that the rumen papillae length in the H group was higher than in the Con group. Amylase concentrations were decreased in the H group than the Con group, whereas the β-glucosidase and cellulase concentrations increased. Compared to the Con group, the relative abundance of propionate and butyrate in the H group was significantly higher. Higher relative abundance of Parabacteroides distasonis and Bacteroides thetaiotaomicron were observed with increasing OEO concentration. The function of rumen microbiota was enriched in the GH43_17 family, mainly encoding xylanase. Besides, metabolites, including heparin, pantetheine, sorbic acid, aspirin, and farnesene concentrations increased with increasing OEO dose. A positive correlation was observed between Parabacteroides distasonis, Bacteroides thetaiotaomicron, and β-glucosidase, cellulase and propionate. The abundance of Parabacteroides distasonis and Parabacteroides_sp._CAG:409 were positively correlated with sorbic acid and farnesene. In summary, OEO supplementation increased the rumen digestive ability by modulating epithelial development and microbiota composition in beef cattle. This study provides a comprehensive insight into the OEO application as an alternative strategy to improve ruminant health production.

Sulfation of Arabinogalactan Proteins Confers Privileged Nutrient Status to Bacteroides plebeius

The human gut microbiota (HGM) contributes to the physiology and health of its host. The health benefits provided by dietary manipulation of the HGM require knowledge of how glycans, the major nutrients available to this ecosystem, are metabolized. Arabinogalactan proteins (AGPs) are a ubiquitous feature of plant polysaccharides available to the HGM. Although the galactan backbone and galactooligosaccharide side chains of AGPs are conserved, the decorations of these structures are highly variable. Here, we tested the hypothesis that these variations in arabinogalactan decoration provide a selection mechanism for specific Bacteroides species within the HGM. The data showed that only a single bacterium, B. plebeius, grew on red wine AGP (Wi-AGP) and seaweed AGP (SW-AGP) in mono- or mixed culture. Wi-AGP thus acts as a privileged nutrient for a Bacteroides species within the HGM that utilizes marine and terrestrial plant glycans. The B. plebeius polysaccharide utilization loci (PULs) upregulated by AGPs encoded a polysaccharide lyase, located in the enzyme family GH145, which hydrolyzed Rha-Glc linkages in Wi-AGP. Further analysis of GH145 identified an enzyme with two active sites that displayed glycoside hydrolase and lyase activities, respectively, which conferred substrate flexibility for different AGPs. The AGP-degrading apparatus of B. plebeius also contained a sulfatase, BpS1_8, active on SW-AGP and Wi-AGP, which played a pivotal role in the utilization of these glycans by the bacterium. BpS1_8 enabled other Bacteroides species to access the sulfated AGPs, providing a route to introducing privileged nutrient utilization into probiotic and commensal organisms that could improve human health. IMPORTANCE Dietary manipulation of the HGM requires knowledge of how glycans available to this ecosystem are metabolized. The variable structures that decorate the core component of plant AGPs may influence their utilization by specific organisms within the HGM. Here, we evaluated the ability of Bacteroides species to utilize a marine and terrestrial AGP. The data showed that a single bacterium, B. plebeius, grew on Wi-AGP and SW-AGP in mono- or mixed culture. Wi-AGP is thus a privileged nutrient for a Bacteroides species that utilizes marine and terrestrial plant glycans. A key component of the AGP-degrading apparatus of B. plebeius is a sulfatase that conferred the ability of the bacterium to utilize these glycans. The enzyme enabled other Bacteroides species to access the sulfated AGPs, providing a route to introducing privileged nutrient utilization into probiotic and commensal organisms that could improve human health.

Functional metagenomics identifies an exosialidase with an inverting catalytic mechanism that defines a new glycoside hydrolase family (GH156)

Exosialidases are glycoside hydrolases that remove a single terminal sialic acid residue from oligosaccharides. They are widely distributed in biology, having been found in prokaryotes, eukaryotes, and certain viruses. Most characterized prokaryotic sialidases are from organisms that are pathogenic or commensal with mammals. However, in this study, we used functional metagenomic screening to seek microbial sialidases encoded by environmental DNA isolated from an extreme ecological niche, a thermal spring. Using recombinant expression of potential exosialidase candidates and a fluorogenic sialidase substrate, we discovered an exosialidase having no homology to known sialidases. Phylogenetic analysis indicated that this protein is a member of a small family of bacterial proteins of previously unknown function. Proton NMR revealed that this enzyme functions via an inverting catalytic mechanism, a biochemical property that is distinct from those of known exosialidases. This unique inverting exosialidase defines a new CAZy glycoside hydrolase family we have designated GH156.