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https://ptsldigital.ukm.my/jspui/handle/123456789/500049| Title: | Characterization of an algicidal bacterium Loktanella sp. Gb03 and its impacts on a toxic dinoflagellate Coolia malayensis |
| Authors: | Anmar Hameed Bloh (P70793) |
| Supervisor: | Asmat Ahmad, Prof. Dr. |
| Keywords: | Bacteria Marine water Toxic dinoflagellate Universiti Kebangsaan Malaysia -- Dissertations |
| Issue Date: | 18-Aug-2017 |
| Description: | The aims of this study were to isolate, screen and identify local algicidal bacteria from marine water and dinoflagellate cultures, to determine the algicidal activity against toxic dinoflagellate Coolia malayensis and to identify the algicidal bioactive compounds. Out of 174 isolates only six (Lysinibacillus sp. Gb01, Loktanella sp. Gb02, Loktanella sp. Gb03, Vibrio owensii Gb04, Vibrio alginolyticus Gb05, Loktanella sp. Gb06) were found to have algicidal activity. Further characterization were performed on selected isolates using scanning electron microscope (SEM), growth characteristic on various media and salt, temperature and pH tolerance. Loktanella sp. UKMGb03 isolated from laboratory culture of the dinoflagellate Gambierdiscus belizeanus was found to have the highest algicidal activity, when 10% (v: v) filtrated supernatant culture of Gb03 was applied to C. malayensis cultures (1.0 × 103 cells/mL), 100% of cells were destroyed after 24 hours. Loktanella sp. Gb03 attacked the dinoflagellate cells indirectly by producing extracellular compounds. The compounds were stable and showed the same activity even when heated at 100°C. Six different solvents (methanol, ethyl acetate, hexane, chloroform, acetonitrile and water) were used to extract the bioactive compounds. The ethyl acetate extract showed the highest activity. Non cytotoxic effect of ethyl acetate extract on Vero cells was observed with cytotoxic concentration (CC50) value determined by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. Antioxidant activity of ethyl acetate extract were determined using DPPH (2,2-diphenyl-1-picrylhydrazyl), and the results showed similarity in the half maximal inhibitory concentration (IC50) values between test compounds and positive control. Ethyl acetate crude extract was purified using column chromatography (CC), thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) techniques to obtain a purified fraction Gbf11. Further analysis using Gas chromatography-mass spectrometry (GC-MS), Nuclear magnetic resonance (1HNMR), Fourier Transform Infra-red (FTIR) and UV absorption showed that Gbf11 fraction is 1H Indole 3 carbaldehyde (C9H7NO). Taken together, there results suggested that Loktanella sp. Gb03 could be a candidate for controlling HABs.,Certification of Master's/Doctoral Thesis" is not vailable |
| Pages: | 179 |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi |
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|---|---|---|---|---|
| ukmvital_98689+SOURCE1+SOURCE1.0.PDF Restricted Access | 309.95 kB | Adobe PDF |  View/Open |
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