Improvement of Biosurfactant Production from West Java Oil Field Indigenous Bacterial Isolate Using Adaptive Laboratory Evolution

• Main Author: Gilang Satrio Nugroh, Gregorius
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/42561
• Institution: Institut Teknologi Bandung

Biosurfactant is a type of surface-active compound (detergent) which has the properties of biodegradability, nontoxicity, effectivity in various environmental condition, as well as selectivity compared to synthetic sufactants. These unique properties have made biosurfactant a global market demand whose value could reach up to 12,5 million tones in a year. However, this high demand doesn’t come with a sufficient amount of supply. Biosurfactant production level is still very low because of low productivity from the producing microbes which makes its production economically inefficient. Previous research has been done on optimizing microbes’ productivity from their nutritional and growth parameters. Therefore, this research aims to do a strain improvement strategy to improve the productivity of biosurfactant-producing microbe using adaptive laboratory evolution (ALE) selected for its tolerance towards synthetic surfactant. The thermophilic hydrocarbonoclastic producing-microbe was isolated from an oil reservoir well in West Java as a wild-type strain (WT). The isolate is further adapted using ALE to increasing concentration of Cetyl-Trimethyl Ammonium Bromide (CTAB) sequentially to obtain resistant strains. The selected resistant strain was further compared with WT for its biosurfactant-producing ability (yield, production rate) and biosurfactant characteristic (activity, structure). A performance stability in terms of biosurfactant production and resistance stability analysis were also done on the resistant strain as criteria for industrial production strain until generation 30. Result showed that a biosurfactant-producing isolate (ABG2) was successfully obtained as WT and a 7 ppm-CTAB-resistant strain (KG7’) was shown to have 3.2 fold-increase (23.5±1.3%) on interfacial tension (IFT) percentage reduction compared to WT (7.4±0.7%). Comparative analysis showed difference on the dynamic of biosurfactant production which was shown from the production kinetics of 2.6 fold-increase in yield (Yp/x) (18,75±1,53mg/108CFU) with a significant decrease in production rate (53,75±6,48mg/L/jam) compared to WT (yield 7,07±0,89mg/108CFU, rate 140,83±10,6mg/L/jam). Biosurfactant activity of KG7’ in various environmental condition was shown to be less stable compared to WT and both biosurfactants were shown to be lipopeptides. Stability analysis showed unstability in terms of resistance and biosurfactant-producing performance. In conclusion, this research has shown that a significant increase in biosurfactant yield could successfully be obtained using ALE selected for CTAB resistance, but further development is still needed to optimize production rate, biosurfactant stability, as well as performance stability of the resistant strain.