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ThesisItem Open Access Characterization and mass production of chitosan from fungi(CCSHAU, Hisar, 2020-06) Aathira S. Kumar; Malik, KamlaChitosan is a linear cationic biopolymer consisting of β (1-4) bonds between 2-amino-2- deoxy-D glucopyranose and 2-acetamido-2- deoxy-D-glucopyranose. It is non-toxic, biocompatible, biodegradable, antimicrobial agent and has high charge density which paves way for its numerous applications especially in the field of agriculture, food and pharmaceuticals. Chitosan, besides chitin, occurs in fungal cell walls particularly of Ascomycetes, Basidiomycetes and Zygomycetes. The enzymatic deacetylation of chitin is the major mechanism for synthesis of chitosan in fungi. Hence, the biological alternatives (fungi) have been used for chitosan production through fermentation technologies. Chitosan has broad antimicrobial spectrum to which gram-negative, gram-positive bacteria and fungi are highly susceptible. In the present study, characterization and mass production of chitosan from fungi was standardized fermentation conditions and determined its antimicrobial properties against pathogenic microorganisms. A total of 18 morphologically different fungal isolates, 17 bacteria and 3 actinomycetes were isolated on chitin agar medium. Out of which, only 6 fungal isolates (FC1, FC3, FC7, FC8, FC9 and FC 16), 2 bacterial isolates (BC 1 & BC 12) and 1 actinomycete (AC 1) showed positive results by production of yellow colour on the chitin agar media supplemented with p-nitroacetanilide as indicator. FC 3 was the most efficient fungal isolate with highest yield of chitosan (0.096 g/100ml). Maximum chitosan production (0.265 g/100ml) was observed at temperature (35˚C) and pH 5 after 96 h of incubation. Glucose (0.309 g/100ml) and yeast extract (0.332 g/100ml) severed as the best carbon and nitrogen source for highest production of chitosan from FC3. When the growth media supplemented with agro-industrial waste @1% paddy straw +1% glucose (w/v) the yield of chitosan (0.315 g/100ml) was increased. The fungal isolates (FC3) showed maximum chitosan production in submerged fermentation (0.533 g/10g paddy straw) as compared to solid state fermentation (0.182 g/10g paddy straw). Therefore, mass production of chitosan from fungal isolate FC 3 was carried out by submerged fermentation in a bioreactor (BioFloR 120) and the yield of chitosan was found to be 5.37 g/l. Further, the chitosan extracted from isolate FC 3 was estimated for degree of deacetylation and it was observed 88.5%. On the basis of morphological and molecular characterisation, the fungal isolate FC 3 was identified as Aspergillus flavus. The antibacterial activities of chitosan at different concentrations were examined against Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus and Xanthomonas. The maximum inhibition zone (8. 0 mm) was observed at 1000 ppm against Escherichia coli. Whereas, the highest percentage of inhibition was observed at 3000 ppm for Rhizoctonia solani (90.73 %) and Fusarium oxysporum (76.27%).