Please use this identifier to cite or link to this item:
https://ptsldigital.ukm.my/jspui/handle/123456789/463566| Title: | Characterization of marine bacteria isolates with algicidal activity against toxic dinoflagellates |
| Authors: | Shaima Abdulfattah Gamal Mohammed (P65075) |
| Supervisor: | Asmat Ahmad, Assoc. Prof. Dr. |
| Keywords: | Marine bacteria Toxic dinoflagellates Algicidal activity Bacterial culture Dissertations, Academic -- Malaysia |
| Issue Date: | 2-Aug-2016 |
| Description: | Algicidal activity of bacteria isolated from coastal waters of Port Dickson and Kelantan against several toxic dinoflagellate species was investigated. Out of 103 bacterial culture isolates that were initially screened for their algicidal activity, 32 isolates were found to be active against Alexandrium minutum and 13 were active against Gambierdiscus belizeanus. Two potential algicidal isolates, designated sdPS-7 and sdPD-4 against Alexandrium minutum, and Aeromonas hydrophila CTT7 (UKM culture collection) were selected for further study. Isolate sdPS-7 demonstrated the highest algicidal activity (≥ 99%) against all tested dinoflagellates within the first 2 hours of treatment. This isolate was resistant to ampicillin, penicillin, bacitracin, DD14 reagent, novobiocin and chloramphenicol. This bacterium showed optimum growth in marine broth medium at pH 7 following 28 hrs of incubation at 28°C and 180 rpm agitation. It also exhibited optimum algicidal activity against two clones of A. minutum when grown in marine broth medium at an initial pH 7 for 24 hrs and shaking speed of 180 rpm. The sdPS-7 bacterium filtrate retained algicidal activity stability (≥ 91%) when treated at different temperatures ranging from 2°C to 100°C. It was also stable under light, dark and UV conditions when treated for 3 hours each. Repeated freezing and thawing also did not affect filtrate activity. The filtrate also retained algicidal activity at pH 5 - 8. Ethyl acetate crude extract (10 mg/ mL w/v) of the sdPS-7 isolate was effective against all tested dinoflagellates and caused cell death within the first hour of treatment. The treated cells morphologywas examined under an inverted light microscope. Most of the treated dinoflagellates cells were observed to have completely lost cell motility and regular shape. This was followed by cell rupture and death. The algicidal activity of the ethyl acetate crude extract was also demonstrated at minimum cytotoxicity concentration values of 5 mg/mL to 0.1 mg/mL when tested against two clones of A. minutum. The crude extract was partially purified by Flash Column Chromatography and six fractions were studied for algicidal activity against three clones of A. minutum. Only one fraction was found active,causing ≥ 95 % cell death within the first hour of treatment. The active crude and fraction were tested for cytotoxicity using 3-(4,5-dimethyl-2-thiazolyl)-2,5 diphenyltetrazolium (MTT) assay. Cytotoxicity concentration (CC50) values obtained were higher than 0.03 mg/mL and were thus considered non toxic. Morphological, biochemical and 16S rRNA sequence analysis revealed the identity of sdPS-7 and sdPD-4 isolates to be Aeromonas hydrophila and Exiguobacterium sp, respectively.,Certification of Master's/Doctoral Thesis" is not available |
| Pages: | 113 |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_84141+SOURCE1+SOURCE1.0.PDF Restricted Access | 117.05 kB | Adobe PDF |  View/Open |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.