Optimization of rhamnolipid production from bioconversion of palm oil mill effluent (POME) waste by Pseudomonas stutzeri BK-AB12 using response surface methodology

Abstract

Rhamnolipid is one of the most widely used biomaterials in the industry due to it has various applications, such as antimicrobial, anti-corrosion, emulsification, bioremediation, and surfactant for enhanced oil recovery. Rhamnolipid is produced by several bacteria that grow in a medium containing high concentration of lipid as a major carbon source. The production of rhamnolipid is still relatively high cost, therefore, this study is aimed to decrease the production cost of rhamnolipid by utilizing palm oil mill effluent (POME) waste as a major carbon source. Pseudomonas stutzeri BK-AB12 has been identified in our previous study as one of the potential rhamnolipid producing bacteria. In order to obtain the best conditions in rhamnolipid production by bacteria, response surface methodology (RSM) was applied in this study. The study begins by observing bacterial growth in a medium salt mineral (MSM) containing POME as a carbon source within concentration 10% to 30% (v/v). The RSM results showed that P.stutzeri BK-AB12 optimally produced rhamnolipid after the fermentation was running for 90 hours in the medium containing POME 20% (v/v) and 0.175% (w/v) urea. The produced rhamnolipid was then extracted and characterized. The critical micelle concentration (CMC) of biosurfactant was about 390 mg•L -1 with a decrease in surface tension of water about 16 dyne•cm -1 , which can be categorized as the potential surfactant for various applications.