Date of Award

4-1-2022

Thesis Type

masters

Document Type

Thesis (Restricted Access)

Divisions

science

Department

Institute of Biological Sciences

Institution

Universiti Malaya

Abstract

Grey oyster mushroom (Pleurotus pulmonarius) is one of the most popular mushrooms in Malaysia and contains a high amount of nutrients. However, the fresh grey oyster mushroom is having short shelf life thus reducing its quality and economic value. Limited study on maintaining the fresh quality and prolonging the shelf life of the fresh grey oyster mushroom. Silver nanoparticles (Ag-NPs) are known to act as antimicrobial agents against a wider range of microorganisms. Therefore, this study aimed to identify the 11 spoilage bacteria strains isolated from rotten grey oyster mushrooms and evaluate the antimicrobial activity of different sizes of Ag-NPs (30.88 nm, 60.52 nm, 99.16 nm) to inhibit the growth of spoilage bacteria using the broth microdilution method. The spoilage bacterial strains were identified as Raoultella ornithinolytica, Raoultella planticola, Klebsiella sp., Enterobacter cloacae, and Cedecea neteri based on biochemical assay and 16S rRNA sequencing. At 50 μg/ml, Ag-NPs (30.88 nm) showed inhibition (ranged from 99.21-100%) on the growth of the 11 strains of spoilage bacteria. Also, Ag-NPs 30.88 nm and Ag-NPs 60.52 nm exhibited higher minimum inhibitory concentration to the spoilage bacteria as compared to Ag-NPs 99.16 nm. In conclusion, smaller-sized Ag-NPs have higher bacterial inhibitory capacity compared to large-sized Ag-NPs.

Note

Dissertation (M.A.) – Faculty of Science, Universiti Malaya, 2022.

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