PRODUCTION AND CHARACTERIZATIONS OF RHAMNOLIPID FROM BIOCONVERSION OF PALM OIL MILL EFFLUENT (POME) BY HALOPHILIC BACTERIUM Pseudomonas stutzeri BK−AB12

• Main Author: RIZKI FAZLI (NIM: 20515049), RAHMAD
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30131
• Institution: Institut Teknologi Bandung

<p align="justify">Rhamnolipid is one of the biosurfactant groups that have been applied as antimicrobial, anticorrosive, bioemulsifier, bioremediation and surfactant for enhanced oil recovery (EOR). Pseudomonas sp has been known as one of the rhamnolipid producer. This study aims to produce and characterize rhamnolipid as a result of bioconversion of palm oil mill effluent (POME) by Pseudomonas stutzeri BK-AB12. The first stage of this study was performing optimization of the bacterial growth on a mineral salt medium (MSM) by varying POME concentration as a carbon source from 5% to 50% (v/v) and urea concentration from 0.2% to 1.5% (w/v) as a nitrogen source. The best medium composition for the bacterial growth was obtained when the MSM medium containing 20% POME and 0.2% urea, pH 7.5 and 5%(w/v) NaCl. The growth curve showed that the bacteria reached the stasionary phase at 48 hours and begin entering the phase of death after 72 hours. Rhamnolipid was produced when bacterial growth reached the end of stasionary phase to the death phase up to 96 hours. In order to verify that the biosurfactant produced by Pseudomonas stutzeri BK-AB12 is rhamnolipid, the rhamnolipid qualitative test on blue agar medium containing cethyltryacetyl bromide-methylene blue (CTAB-MB) was performed and this test gave a positive result by the appearance of dark blues zones around rhamnolipidcontaining wells. The resulted rhamnolipid is extracted and purified to further characterize its physicochemical properties. The characterization results revealed that the rhamnolipid sample showed the highest emulsification index, which was about 71.4%, at pH 9, 15%(w/v) NaCl, and 55oC. The critical micelle concentration (CMC) of this biosurfactant was about 390 mg/L with a decrease in surface tension of water about 16 dyne/cm. Structural analysis using FTIR reaffirmed that the biosurfactant spectrum profile was similar to rhamnolipid. Structural analysis using 1-D 1H NMR showed that fatty acid constituent of rhamnolipid appeared at the chemical shift about 0,6 ppm to 2,4 ppm. Further structural analysis using HRMS have successfully indentified several new structures of rhamnolipid produced by Pseudomonas stutzeri BK&#8722;AB12. This study thus showed that POME can be used as an alternative carbon source to produce rhamnolipid by Pseudomonas stutzeri BK-AB12.<p align="justify">