Production Of Antimicrobial Compounds From A Local Marine Bacterial Isolate, Bacillus Sp. (S1A4)
| dc.contributor.author | Hui Ming, Lim | |
| dc.date.accessioned | 2018-06-07T04:22:53Z | |
| dc.date.available | 2018-06-07T04:22:53Z | |
| dc.date.issued | 2007-03 | |
| dc.description.abstract | A total of 160 strains of marine microorganisms were supplied by the Fisheries Research Institute, Penang. They were collected from samples all over the shores of Malaysia. Out of those, 134 were bacterial strains, 9 actinomycetes, 3 fungal and 14 yeast isolates. About 113 isolates were found to produce pigments. Non - pigmented strains (white colonies) were the most commonly found (26%) while the yellow coloured strains followed with a close second (25%), orange pigmented isolates (16%), and the rest were brown, beige, light green, dark blue, red, grey and transparent isolates in a small percentage. Among the marine isolates provided, only 88 isolates were tested for antimicrobial activity. 59.1 % exhibited antimicrobial activity (52 isolates) of which, 50.0% (42 isolates) exhibited antibacterial activity, 10.3% (9 isolates) antifungal activity and 10.2% (9 isolates exhibited both antibacterial and antifungal activities. The distribution of the antimicrobial compounds in the three selected isolates showed that ali of them produced both extracellular and cell - bound antimicrobial compounds. The isolate S 1 A4 was chosen for further experiments because it exhibited a wide spectrum of activity, was easily subcultured, and grew well in the cultivation medium. The isolate S 1 A4 was identified as the genus Bacillus sp. The production of antimicrobial compounds was enhanced by optimizing physical (culture conditions) and physiological (medium compositions) conditions. The optimized cultural conditions were: 150 rpm for the agitation speed, 4% (v/v) of 3 x 108 cells/ml of the inoculum size, initial pH medium of 7.3 and the incubation temperature was fixed at 3rC. About 50ml of natural filtered sea water was used in making the cultivation medium which consisted of 0.40% (w/v) of starch, 0.50% (w/v) of peptone, 0.20% (w/v) of yeast extract, 0.01 % (w/v) of ferric phosphate, 0.09% (w/v) of L-arginine and 0.05% of KC!. Even though the production of antimicrobial compounds started during its exponential growth phase, maximum production was achieved during the idiophase. After optimization using the shake flask system, there was an increase of 29.6 U/ml or 39.6% increment in antimicrobial compound production. After optimization in the shake flask system, a tubular airlift fermenter with a 2.0L capacity was used for scaling up and then all the parameters were again reoptimized. The optimized conditions were: 4 IImin of aeration, 4% (v/v) (3 x 108 cells per ml) of initial inoculum size and initial pH of 7.3. Filtered natural sea water was used in making the medium which consisted of : 0.5% (w/v) of starch, 0.6% (w/v) peptone, 0.2% (w/v) of yeast extract, 0.01 % (w/v) ferric phosphate, 0.09% (w/v) of L-arginine and 0.05% of KC!. An increment of about 13.8% (4.1 U/ml) of antimicrobial compound production was obtained after optimization in a tubular airlift fermenter. Characterization of the crude extract of the antimicrobial compound found that it was thermostable in a temperature range between 35"C - 65°C, and pH stable between the pH values between 6 -10. The antimicrobial compounds exhibited bactericidal activity against the cells of Staphylococcus aureus .SEM and TEM micrographs showed that the antimicrobial compound lysed the cell wall of S. aureus besides interfering with the intemal structure of the ceils. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/5704 | |
| dc.subject | Antimicrobial Compounds | en_US |
| dc.subject | Bacillus Sp. (S1A4) | en_US |
| dc.title | Production Of Antimicrobial Compounds From A Local Marine Bacterial Isolate, Bacillus Sp. (S1A4) | en_US |
| dc.type | Thesis | en_US |
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