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Title:	Production of biosurfactant from indigenous iranian bacterial isolates: characterization, optimization and development of fermentation system
Authors:	Fooladi Tayebeh (P52561)
Supervisor:	Aidil Abdul Hamid, Prof. Madya Dr.
Keywords:	Bacterial Isolates Biosurfactants
Issue Date:	9-Feb-2015
Description:	Biosurfactants are microbially produced molecules that show excellent surface-active properties. Biosurfactants have become of interest due to their wide variety of potential applications. In this study, ten potential Iranian isolates obtained from soil samples contaminated with oil were investigated. Isolate 2IR was chosen as the best candidate for biosurfactant production, based on preliminary tests such as emulsification activity and surface tension reduction. Isolated strain was identified as Bacillus pumilus based on morphological, biochemical and 16S rRNA sequencing tests. Analysis of the biosurfactant by thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC) showed the presence of five fractions and structural composition of these separate fractions was further identified using infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and Mass spectrometry (LC-ESI) techniques. The biosurfactant produced by B. pumilus 2IR was found to be lipopeptidic in nature. The biosurfactant which was produced as a primary metabolite associated with growth of B. pumilus 2IR was able to reduce the surface tension of media to 34 mN/m with critical micelle concentration of 120 μg/mL. Optimal environmental conditions for high lipopeptide production at the shake-flask level were, pH of 6-8, temperature at 30 °C and NaCl concentration of 5% during 72 h of incubation time. For media components, results showed that the favored carbon source was glucose, whereas the optimum nitrogen sources were potassium nitrate and ammonium sulfate with C/N ratio of 12. Biosurfactant production and biomass concentration by isolate 2IR were achieved in shake-flask with optimized media to 0.75 g/L and 3.18 g/L, respectively. Further medium optimization using statistical experimental design (Response surface methodology, RSM) resulted in a 12% increase in biosurfactant production when using glucose, crude oil, potassium nitrate and ammonium sulfate at concentrations of 30.31 g/L, 0.8 % (v/v), 2.88 g/L and 2.4 g/L, respectively with maximum reduction in surface tension (30.5 mN/m). Comparison of biosurfactant production using different modes of fermentation; shake-flask, batch and fed-batch cultivation in a 5-L stirred tank fermenter was studied. Fed-batch fermentation gave the highest biosurfactant production (1.06 g/L) with an improvement of 26% and 11.5% as compared to biosurfactant production obtained in shake-flask and batch culture in 5-L fermenter using optimized medium, respectively. Moreover, biomass concentration obtained in fed-batch fermenter improved by 1.6 fold compared to shake-flask cultivation and 1.4 fold over the batch study.,PhD / Doktor Falsafah
Pages:	199
Call Number:	TP248.B57F644 2015 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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