The optimal environmental and nutritional conditions for chitosan production by A.niger strains (A4 and A11)were studied .However, molasses and corn steep liquor as carbon and nitrogen sources were used for maximization chitosan production. Results showed that the highest records of biomass, chitin and chitosan produced by both strains were observed when sucrose and urea were used at a rate of 75 g/l , 1.7 g/l as a sole carbon and nitrogen sources, respectively. Increasing the incubation temperature led to gradual increase in biomass and chitosan yield up to 28 ˚C for both strains . The highest values of chitosan production were obtained when both strains of A.niger were incubated at pH 4.5 for 7 days then decreased thereafter. Moreover, increasing of corn steep liquor as nitrogen source to reach their maximum chitosan production at 150 g/l. Results indicated that the two Aspergillus strains produced higher amounts of chitosan when cane molasses was used as a carbon source rather than beet molasses. However , maximum values of chitosan were observed when mixture of cane and beet molasses was used as a sole carbon source.
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