Bacterial nanocellulose (BNC) biosynthesis by Komagataeibacter hansenii RM-03 using agricultural waste as substrates and BNC-silver nanocomposite preparation

Bacterial nanocellulose (BNC) is a biopolymer synthesised by bacterium, forming ultrafine nanofibrils with properties surpassing those of other cellulose types. Despite its potential, conventional HS medium, particularly its carbon source, contributes to high production costs and low productivity. This study explores BNC biosynthesis on a modified HS medium, employing agricultural wastes (sugarcane molasses, banana peel, and pineapple peel) as carbon sources while comparing the overall BNC yield. Sugarcane molasses emerged as the most effective, yielding the highest BNC concentration (8.19 g/L) after 7 days, followed by pineapple peel (2.16 g/L) and banana peel (2.11 g/L). Extensive research was conducted to enhance the properties of BNC by an environmentally friendly approach, incorporating silver nanoparticles (AgNP) utilising Momordica charantia fruit extract, resulting in a BNC-Ag nanocomposite. The synthesis involved mixing 1 mM silver nitrate (AgNO3) with 15 mL of M. charantia fruit extract to reduce Ag ions to AgNP, which was confirmed by UV-vis spectroscopy with an absorbance peak at 408 nm. Furthermore, the characterization of BNC on FESEM and TEM demonstrated that the wastes as carbon sources had little impact on the diameter of the BNC fibre, whereas XRD revealed slight differences in crystallinity index, with up to 85 % obtained on sugarcane molasses-derived BNC. The FTIR analysis revealed similar chemical profiles on all the BNC, which also indicates the formation of cellulose. The BNC-Ag nanocomposite exhibited potent antibacterial activity against gram-negative bacteria; Pseudomonas aeruginosa and Salmonella typhi, as well as gram-positive bacteria; Bacillus subtilis and Staphylococcus aureus through the disc diffusion method, with a diameter of inhibition zones up to 16.8 mm. The findings highlight the great ability of BNC to preserve its remarkable properties and the potentiality of agricultural wastes to replace conventional HS medium, as well as BNC-Ag nanocomposite as an antibacterial material, therefore paving the way for more widespread commercial applications of BNC in the future.

Text 125112 - Full Text.pdf Download (4MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18806

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