Examining the interplay between Streptococcus agalactiae, the biopolymer chitin and its derivative

Kinetic Modeling of an Enzyme Membrane Reactor for the Selective Production of Oligosaccharides

An enzyme membrane reactor is an attractive tool for producing oligosaccharides from biomass-based polysaccharides. However, kinetic modeling and reactor design based on the rate equations have rarely been reported for enzyme membrane reactors because of the difficulty in tracing the depolymerization process. In this study, a simplified reaction model based on Michaelis–Menten-type kinetics has been built to simulate the enzyme membrane reactor. Ramping various species into reactant, target, and byproduct worked well for discussing reactor performance. The use of a membrane with a molecular weight cut-off (MWCO) of 10 kDa with continuous feeding of the reactant was suggested for the efficient production of chitosan hexamer and pentamer by enzymatic hydrolysis of chitosan.

Antimicrobial Activities of Alginate and Chitosan Oligosaccharides Against Staphylococcus aureus and Group B Streptococcus

The bacterial pathogens Streptococcus agalactiae (GBS) and Staphylococcus aureus (S. aureus) cause serious infections in humans and animals. The emergence of antibiotic-resistant isolates and bacterial biofilm formation entails the urge of novel treatment strategies. Recently, there is a profound scientific interest in the capabilities of non-digestible oligosaccharides as antimicrobial and anti-biofilm agents as well as adjuvants in antibiotic combination therapies. In this study, we investigated the potential of alginate oligosaccharides (AOS) and chitosan oligosaccharides (COS) as alternative for, or in combination with antibiotic treatment. AOS (2-16%) significantly decreased GBS V growth by determining the minimum inhibitory concentration. Both AOS (8 and 16%) and COS (2-16%) were able to prevent biofilm formation by S. aureus wood 46. A checkerboard biofilm formation assay demonstrated a synergistic effect of COS and clindamycin on the S. aureus biofilm formation, while AOS (2 and 4%) were found to sensitize GBS V to trimethoprim. In conclusion, AOS and COS affect the growth of GBS V and S. aureus wood 46 and can function as anti-biofilm agents. The promising effects of AOS and COS in combination with different antibiotics may offer new opportunities to combat antimicrobial resistance.

Examining the interplay between Streptococcus agalactiae, the biopolymer chitin and its derivative

Streptococcus agalactiae is a highly pathogenic bacterium of aquatic species and terrestrial animals worldwide, whereas chitin and its derivative chitosan are among the most abundant biopolymers found in nature, including the aquatic milieu. The present investigation focused on the capability of S. agalactiae to degrade and utilize these polymers. Growth of S. agalactiae in the presence of colloid chitin, chitosan, or N‐acetyl‐glucosamine (GlcNAc) was evaluated. Chitosanase production was measured daily over 7 days of growth period and degraded products were evaluated with thin later chorography. Chitin had no effect on the growth of S. agalactiae. Degraded chitin, however, stimulated the growth of S. agalactiae. S. agalactiae cells did not produce chitinase to degrade chitin; however, they readily utilize GlcNAc (product of degraded chitin) as sole source of carbon and nitrogen for growth. Chitosan at high concentrations had antibacterial activities against S. agalactiae, while in the presence of lower than the inhibitory level of chitosan in the medium, S. agalactiae secrets chitosanase to degrade chitosan, and utilizes it to a limited extent to benefit growth. The interaction of S. agalactiae with chitin hydrolytes and chitosan could play a role in the diverse habitat distribution and pathogenicity of S. agalactiae worldwide.