Implications of recovery procedures on structural and rheological properties of schizophyllan produced from date syrup.

This study investigates the effects of different recovery procedures on high molar mass schizophyllan produced by Schizophyllum commune using low value agricultural residues. Recovered extracellular polysaccharides (EPSs) were compared in terms of purity, sugar composition, degree of branching, molecular weight, and rheological properties. Performing different recovery methods, such as re-dissolving in water and re-precipitation with ethanol on produced EPS, provided schizophyllan with purity similar to the commercial grade. Besides, Freeze-thawing cycles allowed the fractionation of schizophyllan based on branching degree and solubility. The EPSs with higher purity and lower degree of branching (less conformational flexibility) showed higher viscosity. This study evidences the possibility of producing EPSs with excellent rheological properties using low value agricultural side products. Furthermore, our results demonstrate the importance of recovery methods for tailoring the purity, molecular structure and macroscopic properties of the produced polysaccharides for specific applications.

Characterization and optimization of schizophyllan production from date syrup.

This study demonstrates the efficient utilization of low-cost agricultural substrates, particularly date syrup, by Schizophyllum commune ATCC 38548 for schizophyllan production. Initially, one factor-at-a-time method was used to find the best carbon and nitrogen sources for schizophyllan production. Subsequently, response surface methodology was employed to optimize the level of culture medium components to maximize substrate conversion yield and schizophyllan production in submerged culture. Maximum product yield (0.12g schizophyllan/g date syrup) and schizophyllan production (8.5g/l) were obtained at concentrations of date syrup and corn steep liquor, inoculum size and agitation rate at 7.02%w/v, 0.10%w/v, 7.68%v/v and 181rpm, respectively. Sugar composition analysis, FTIR, NMR and molar mass determination revealed the purity and molecular properties of recovered schizophyllan produced from date syrup as glycosidic linkage analysis showed three main schizophyllan characteristic peaks arising from the 3-linked, 3,6-linked and terminal glucose residues. Finally, process economic analysis suggested that use of date syrup and corn steep liquor as nutrients would result in approximately 6-fold reduction in cost of raw materials for schizophyllan production as compared to conventional carbon and nitrogen sources such as sucrose and malt extract.

Biodegradation of phenol by Ralstonia eutropha in a Kissiris-immobilized cell bioreactor.

This study examined the biodegradation of phenol by Ralstonia eutropha in a Kissiris-immobilized cell bioreactor (ICB), operated in a repeated batch recycling mode. The steady biodegradation rate of 23.7 mg/g/h, over a wide range of the initial phenol concentrations up to 1400 mg/L in the ICB, indicated an increased tolerance limit of the Kissiris-immobilized cells towards phenol. Both Haldane and Luong substrate inhibition models were used to describe biodegradation kinetic of free cells system. The Haldane equation gave the following values for the biokinetic parameters: micro(max) = 0.36 h(-1), Ks = 40.48 mg/L, and Ki = 181.9 mg/L. However, according to the Luong model, these parameters were micromax) = 0.23 h(-1), Ks = 24.8 mg/L, Sm = 1018 mg/L, and n = 1.3. By following appropriate operational conditions and use of the ICB, it was found to be possible to extend the efficiency of the highly porous structure of the siliceous mineral Kissiris in cell immobilization. This holds significant promise for pollutant biodegradation issues.