Size Optimization of Lemongrass (Cymbopogon citratus) Essential Oil Nanoparticles as Antimicrobial Substance against Bacteria Isolated from South Sumatran Formation Water

Microbiologically influenced corrosion (MIC) caused by biofilm is one of the main cause of pipelines failure in oil and gas industry. Lemongrass (Cymbopogon citratus) essential oil (LEO) can serve as an environmentally friendly alternative for toxic chemical biocide such as glutaradehyde. This research aimed to optimize lemongrass essential oil nanoparticles formulation and to determine its antimicrobial activity against biofilm forming consortium isolated from formation water taken from South Sumatran oil reservoir. The formulation was optimized by varying chitosan concentration, tween 80 concentration, and CS/TPP ratio. The optimum formulation resulting in smallest nanoparticles size (1.8 nm) was obtained with 0.125% chitosan, 0.5% tween 80, and 6/1 ratio of CS/TPP. Antimicrobial activity of 49 nm (LNP) and 1.8 nm (SNP) sized nanoparticles were tested against planktonic bacteria and biofilm. Minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) were used as parameters. LEO concentration of 0.06% was observed as MIC for both formula. MBIC and MBEC was not observed up until 0.15% LEO. However, LNP was observed to exhibit higher ability to inhibit and eradicate biofilm. Based on MIC, MBIC, and MBEC, 49 nm sized nanoparticles (LNP) showed the highest antimicrobial activity.