Production of Chitosan by Some Fungi and Its Industrial Applications

Chitosan production from microorganisms is the main aim of this research. Seventeen fungi were isolated from agricultural soil located in Cairo, Egypt. These isolated fungi were preliminary identified and screened for chitosan content. The best chitosan producer with the highest chitosan content was Rhizopus oryzae. The chitinious matter was 255.0 mg/g.The fungus was identified using 18 S rRNA revealing it was Rhizopus oryzae 1.3.32. Crustacean chitosan was extracted to be compared with the fungal chitosan. It was extracted from shrimp shells with 16% chitosan content. Chitosan samples were characterized by Fourier Transmission Infra Red (FTIR) spectrophotometry, X-ray diffraction (XRD), viscosity analysis and thermogravimetry (TGA). One way fermentation experiments were carried out to optimize the environmental conditions including; temperature, agitation, ph, inoculum size, spore age, carbon source, nitrogen source and minerals addition) which gave the maximum chitosan production by Rhizopus oryzae. Fungal chitosan was tested for its adsorption ability with Cu⁺⁺ in the form of cupper sulphate compared with the standard and crustacean chitosan. All chitosan samples showed potential ability to adsorb Cu⁺⁺ in aqueous solution. Fungal chitosan showed high spectrum antibacterial activity. The bacteria were Staphylococcus aureus, Streptococcus epidermidis, Staphylococcus aureus, two isolates of Escherichia coli 1, Escherichia coli 2 and Pseudomonas aeruginosa. In a trial to decrease the costs, a substitution of some components in PGY occurred. Molasses was added to Peptone yeast forming peptone molasses yeast (PMY) medium. Wheat bran was also added to glucose to form wheat bran-glucose (WBG) medium. the medium yielde higher fungal chitosan was PMY since the chitosan was 137.1 mg/g. A mixture of molasses and wheat bran (MWB) medium was tested as a fermentation medium and the chitosan yield was 50.83 mg/g. Chitosan from Rhizopus oryzae grown in MWB natural medium was characterized by studying the FTIR, XRD, TEM and viscosity analysis. The deacetylation degree and average molecular weight were determined for all chitosan samples. Different doses of Gamma irradiation on Rhizopus oryzae spores increased chitosan production, especially 6 Gy with PGY medium. When the low-cost media were inoculated with spores irradiated by 6 Gy, chitosan yield increased with MWB and WBG media. The two extracted chitosan samples from Rhizopus oryzae along with that extracted from shrimp shells and the standard marine chitosan were irradiated with 0.25, 0.5, 1.0, 2.0, 5.0 and 10.0 kGy. The dose of 10.0 kGy influenced the viscosity of all chitosan samples and it was revealed by the changed viscosity and the decreased molecular weigh