Saccharomyces Cerevisiae as an Untapped Source of Fungal Chitosan for Antimicrobial Action

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

Mixed organic and inorganic nitrogen sources enhance chitosan yield in novel isolates of Penicillium

Chitosan, a valuable biopolymer, has traditionally been derived from marine sources. However, exploring fungal alternatives offers a sustainable supply. This research investigates the potential of chitosan production from fungal sources, focusing on the optimization of abiotic factors using two novel Penicillium strains (IITISM-ANK1 and IITISM-ANK2) isolated from dry aged sludge. Box-Behnken model and standard statistical analysis were deployed to develop an equation predicting the effect of carbon and nitrogen sources, pH, and temperature on chitosan production. Batch experiments validate the model's accuracy under optimized conditions. The results indicate that mixed organic and inorganic nitrogen sources in the form of peptone, nitrate, and ammonium salts enhanced chitosan yield in both isolates. At optimal conditions for the chitosan production of IITISM-ANK2 and IITISM-ANK1 were found to be 293.29 mg/L and 325.01 mg/L, with the degree of deacetylation of over 74 % which is a critical parameter for chitosan quality. Thus, these isolates can be used as a potent microbe for industrial chitosan production and contribute to advancing sustainable chitosan production and its potential industrial applications.

Low molecular weight chitosan oligosaccharides form stable complexes with human lactoferrin

Proteins in tears, including human lactoferrin (HLF), can be deposited and denatured on contact lenses, increasing the risk of microbial cell attachment to the lens and ocular complications. The surfactants currently used in commercial contact lens care solutions have low clearance ability for tear proteins. Chitosan oligosaccharide (COS) binds to a variety of proteins and has potential for use in protein removal, especially in contact lens care solutions. Here, we analyzed the interaction mechanism of COSs hydrolyzed from chitosan from different resources with HLF. The molecular weights (MWs) and concentrations of COSs were key factors for the formation of COS-HLF complexes. Lower MWs of COSs could form more stable COS-HLF complexes. COS from Aspergillus ochraceus had a superior effect on HLF compared with COS from shrimp and crab shell with the same MWs. In conclusion, COSs could bind to and cause a conformational change in HLF. Therefore, COSs, especially those with low MWs, have potential as deproteinizing agents in contact lens care solution.

Banana peels as a cost effective substrate for fungal chitosan synthesis: optimisation and characterisation

Massive accumulation of unprocessed banana peels enthralls sustainable issues as they are eventually dumped as landfills leading to emission of obnoxious gasses. To avoid these persisting challenges the present study shims lights on chitosan production from the characterised fungal strain using banana peel hydrolysate as an effective medium. Substantial amount of carbohydrate in banana peels serves as a potential solution for fungal chitosan production in a view to attain a circular bioeconomy and repurposed for synthesis of beneficial products in a cost effective manner. Presence of fermentable sugars in banana peels qualifies them as a feasible substrate which could be exploited for scaling up of fungal chitosan synthesis. Screened isolate was subjected to statistical optimisation using formulated medium to elucidate the influential factors that had significant effect on chitosan production. The harvested chitosan biomass was characterised through standardised techniques and evaluated for further studies. Statistical optimisation reveals that ammonium nitrate (5 g/L), pH (6) and incubation time (144 hrs) were the three PBD variables that had a greater influence on fungal chitosan yield. The validated developed model exhibited maximum yield of 200 mg/L, a 4.4 fold increase than unoptimised medium (45 mg/L). These findings emphasise the fermentative synthesis of chitosan through valorisation of banana peel prop up a complementary approach in concomitant with preserving renewable resources and bioproduct formation.