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https://ptsldigital.ukm.my/jspui/handle/123456789/499717| Title: | Production and characterization of biosurfactant from local isolate and application in removal of crude oil from sand |
| Authors: | Zahra Shafiei (P51228) |
| Supervisor: | Wan Mohtar Wan Yusoff, Prof.Dr.HJ. |
| Keywords: | Biosurfactants Crude oil. Sand Biosurfactants. |
| Issue Date: | 6-May-2015 |
| Description: | The potential of indigenous bacterial isolates from a soil sample was taken at Terengganu oil refinery, in Malaysia for the production of biosurfactants was investigated. Morphological tests revealed that the bacteria forms white, flat, irregularly edged colonies. It was characterized as motile, Gram positive and spore forming and positive for oxidase, catalase and nitrate reduction. The isolate hydrolyzed starch, casein, gelatin and Tween 80. The isolate could also utilize glucose, fructose, mannitol, xylose and arabinose. These results identified strain 8M as a member of the bacillus group. In this study, the 16S rRNA gene sequence (1525 bp) of isolate 8M was compared with sequences from B. subtilis group type strains and other closely related taxa. The morphological and biochemical characteristics and the 16S ribosomal deoxyribonucleic acid gene sequence revealed that strain 8M is Bacillus mojavensis. An initial screening test was conducted on eight different bacteria isolates for the production of biosurfactant activity. Isolate 8M produced the highest concentration of biosurfactants and demonstrated the highest of activities based on the following factors: blood agar lysis (2.5 cm), the oil-spreading test (19 mm) and drop collapse test 42 mm. Isolate 8M was also able to reduce the surface tension of the medium E from 60 mN/m to 28.5 mN/m with an emulsification index (E24) of 83% and 80% for hexadecane and crude oil, respectively. The aim of the present work was to achieve high production of biosurfactant from the newly isolated local strain, by investigating various factors on growth and biosurfactant production and the response was evaluated followed by measuring the surface tension activity (mN/m), acid precipitated biosurfactant concentration (g/L) and biomass concentration (g/L).The maximum concentration of biosurfactant (0.85 g/L) was obtained when sucrose at the concentration of 1% w/v and potassium nitrate at 0.1% w/v were employed as carbon and nitrogen sources respectively, with a C/N ratio of 8. The highest reduction in surface tension (27 mN/m) was obtained under the optimal conditions of 35°C, 50 g/L NaCl concentration and an initial pH 7.0. Biosurfactant production is growth associated when B. mojavensis 8M was cultivated in medium E and the duration of fermentation is 4 days. The biosurfactant produced by B.mojavensis 8M was recovered by acid precipitation and was extracted with methanol. A purification protocol was developed and a thorough qualitative and quantitative speciation analysis was performed with liquid chromatography-mass spectrometry. Identities of isolated products were verified by using Thin Layer Chromatography (TLC), high performance liquid chromatography (HPLC), Liquid Chromatography-Mass Spectrometry (LC-MS), Nuclear Magnetic Resonance Spectroscopy (NMR), and infrared spectroscopy (FT-IR), further analysis was carried out to identified the lipopeptide. The chemical characterization showed that the four isolates produced very similar mixtures, containing C13-, C15- and C18- surfactin, although in different proportions. The structure of surfactins produced by the strain was shown to be in good agreement with their mass fragmentation. Product ions are observed at molecular weight (M/W) 1036, 1047, 1078 and 1120 corresponding to C53H93N7O13, C54H95N7O13, C56H95N7O13 and C59H105N7O13, respectively. The efficiency of the residual oil recovery increased by 37.5% after the addition of cell free, 3 days old culture in a sand-packed column saturated with crude oil.,Ph.D |
| Pages: | 157 |
| Call Number: | TP248.B57 Z334 2015 |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi |
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| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_81741+SOURCE1+SOURCE1.0.PDF Restricted Access | 4.32 MB | Adobe PDF |  View/Open |
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