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oai:openscholar.dut.ac.za:10321/54452025-04-03T01:11:17Zcom_10321_5col_10321_6

Development of chitosan biopolymer films by fungal fermentation of waste substrates Naidoo, Krinolen Krishna Rajahrathanum Permaul, Kugen Govender, Algasan Puri, Adarsh Kumar Waste substrates Biomass energy Water--Waste Biopolymers Zygomycetes Submitted in fulfillment for the Degree of Master of Applied Science in Biotechnology, Durban University of Technology, Durban, South Africa, 2024. Zygomycetes are known for their relatively high chitosan content (approximately 10% m/m) in comparison with other fungal genera. In this study, Mucor circinelloides was grown on the following industrial waste substrates: corn steep liquor (CSL); soft drink overflow spillage waste (DBW); and sugarcane molasses (MOL). Biomass production on waste substrates was statistically optimized by Plackett-Burman design in conjunction with Response Surface Methodology, followed by validation of the model. DBW hindered fungal biomass growth and was found to be a statistically insignificant variable and therefore omitted from further optimizations. The validated model produced a biomass of 77.87 g/L, a 2.65-fold increase over the highest-yielding unoptimized medium. Fungal biomass obtained after batch fermentation was subjected to acid-alkaline treatment for chitin extraction from the cell wall and deacetylation of the chitin to chitosan. A yield of 8-9% chitosan was obtained from the fungal biomass. FTIR spectroscopic analysis was conducted on the extracted fungal chitosan to compare extracted chitosan against commercial chitosan and chitosan monomer. The waste-grown, fungal-derived chitosan profiles were similar to those of commercial crustacean chitosan. The extracted chitosan was used in conjunction with additives and solvent systems to create biopolymer variants with differing properties. A library of data from the chitosan biopolymer variants was generated with considerable differences in characteristics based on their composition. Improvements in sample #11 (the most modified formulation) in contrast to the most common chitosan biopolymer film composition used in literature (sample #9), included a 3.37-fold improvement in the static force required to break the film. There was a 3.39-fold increase in tensile strength and an 11-fold reduction in elongation (%) and elongation rates. The creation of these variants will allow the use of these chitosan biopolymers for specific industrial applications. M 2024-09-02T07:28:18Z 2024-09-02T07:28:18Z 2024-05 Thesis https://hdl.handle.net/10321/5445 https://doi.org/10.51415/10321/5445 en 116 p application/pdf