Degree

Doctor of Nutrition and Food Sciences (PNFS)

Department

School of Nutrition and Food Sciences

Document Type

Dissertation

Abstract

Bacterial cellulose (BC), composed of cellulosic nanofibrils, is synthesized by a symbiotic culture of bacteria and yeast during the fermentation of coffee kombucha (CK). BC may be used as a purification agent and adsorbent. The overall goal of this project was to synthesize BC from CK fermentation and assess its efficacy in removing pathogenic bacteria from contaminated water and a pollutant dye from aqueous solution. The objectives of this study were to: (1) compare BCs that were produced from different carbohydrate substrates in the fermentation of CK, (2) characterize dried BCs produced using various drying methods, (3) evaluate BC as a filtration film to remove bacteria from contaminated water and also its ability to adsorb brilliant green (BG) (a pollutant dye) from aqueous solution, and (4) evaluate the biodegradability of BC under soil for two months.

Sucrose, dextrose, fructose, and mannitol were used as substrates to synthesize BCs. CKs containing 15% dextrose produced the highest BC yields. Four drying methods were utilized to produce unique BCs: oven-drying, freeze-drying, vacuum oven-drying, and Büchner funnel vacuum-drying. Freeze-dried BC was the thickest (mm) and contained higher porosity than oven-dried BCs, which showed no porosity. A filtration unit was constructed to test the efficacy of BC as a filtration film. BCs in the filtration unit successfully removed Listeria and E. coli surrogate microorganisms with removal efficiencies of 99%. BC was used as an adsorbent in a batch and a fixed-bed column adsorption processes to remove BG from an aqueous solution. The batch adsorption process removed 98% of the dye in 4 h. Moreover, BC removed approximately 50% BG when tested as a fixed-bed adsorption column. The biodegradability of BC was confirmed with approximately 90% BC degraded after eight weeks below soil. Scanning electron microscopy images showed BC structural changes due to biodegradation. Fatty acid methyl esters microbial analysis suggested that fungi mainly drove BC biodegradation. DNA genomic studies showed significant soil microbial community variations after two weeks of biodegradation. This study demonstrated that BC synthesized from CK was biodegradable and could be utilized in the removal of pathogenic bacteria and BG from contaminated water.

Committee Chair

Sathivel, Subramaniam

Available for download on Saturday, May 24, 2025

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