Role of Bacteria-Derived Exopolysaccharides in Inflammatory Bowel Disease with a Special Focus on Cyanobacterial Exopolysaccharides

International audienceInstances of inflammatory bowel disease (IBD), a chronic inflammatory condition of the gastrointestinal tract, are rapidly increasing in western and newly industrialized countries. Exopolysaccharides (EPSs) are one of the strategies to enhance the gut microbiota and modulate the immune-inflammatory response deregulation in IBD patients. EPSs are produced by commensal bacteria such as Lactobacillus and Bifidobacterium. Additionally, Cyanobacteria species are promising sources of novel EPS and have potential pharmaceutical and therapeutic applications. The presence of uronic acids and sulphate groups in Cyanobacterial EPSs is an important factor that gives EPSs an anionic charge that is not seen in other prokaryotic species. This feature may impact their physico-chemical characteristics and biological properties. Additionally, Cyanobacterial EPSs have a wide range of biotechnological applications that include use as thickeners, stabilizers, and gelling agents in the food and pharmaceutical sectors. The present review focuses on the role of EPSs in IBD, with a special focus on EPSs derived from Cyanobacteria. This review also covers the biological properties of Cyanobacterial EPS in immuno-inflammatory responses and against pathogens as well as its role in biotechnological applications. Overall, Cyanobacterial EPSs have therapeutic potential against IBD due to their anti-inflammatory and immunoregulatory properties that can reduce inflammation and regulate the immune response and restore the gut microbiota of patients

Synthesis and Structural Characterization of Selenium Nanoparticles–<i>Bacillus</i> sp. MKUST-01 Exopolysaccharide (SeNPs–EPS) Conjugate for Biomedical Applications

Exopolysaccharides (EPS) are exogenous microbial metabolites generated predominantly during the development of bacteria. They have several biological potentials, including antibacterial, antioxidant, and anticancer actions. Polysaccharide-coated nanoparticles have high biological activity and are used in treatments and diagnostics. In this research, selenium nanoparticles (SeNPs) are synthesized and conjugated with bacterial (Bacillus sp. MKUST-01) exopolysaccharide (EPS). Initially, the creation of SeNPs conjugates was verified through UV–Vis spectral examination, which exhibited a prominent peak at 264 nm. Additionally, X-ray diffraction (XRD) analysis further substantiated the existence of crystalline Se, as evidenced by a robust reflection at 29.78°. Another reflection observed at 23.76° indicated the presence of carbon originating from the EPS. Fourier transform infrared spectroscopy (FT-IR) analysis of the EPS capped with SeNPs displayed characteristic peaks at 3425 cm−1, 2926 cm−1, 1639 cm−1, and 1411 cm−1, corresponding to the presence of O-H, C-H, C=O, and COO–groups. The SeNPs themselves were found to possess elongated rod-shaped structures with lengths ranging from 250 to 550 nm and a diameter of less than 70 nm, as confirmed using scanning electron microscopy and particle size analysis. In contrast to the SeNPs, the SeNPs–EPS conjugates showed no hemolytic activity. The overall antioxidant activity of SeNPs–EPS conjugates outperformed 20% higher than SeNPs and EPS. Additionally, experimental observations involving gnotobiotic Artemia nauplii experiments were also recorded, such as the supplementation of EPS and SeNPs–EPS conjugates corresponding to enhanced growth and increased survival rates compared to Artemia nauplii fed with SeNPs and a microalgal diet