Use of agricultural wastes in rhamnolipid production by Pseudomonas aeruginosa USM-AR2

Abstract

This study investigates agricultural wastes as potential fermentation substrates to provide a cheaper solution in rhamnolipid production by P. aeruginosa USM-AR2 while simultaneously attempting to recycle waste. Rhamnolipid production was estimated by orcinol assay, oil spreading test (OST), and emulsification index (E24). The wastes used were waste cooking oil and glycerine pitch. Rhamnolipid fermentation was carried out in shake flask culture using minimal salt medium (MSM) supplemented with 3% (v/v) agricultural wastes as the sole carbon source and NaNO3 as the nitrogen source. MSM supplemented with waste cooking oil exhibited higher biomass, while glycerine pitch resulted in higher rhamnolipid production. Rhamnolipid from MSM supplemented with waste cooking oil demonstrated higher diameter of clearing zone in the OST than glycerine pitch. It exhibited high emulsification activity on waste cooking oil at 63.3 ± 0.03%, with glycerine pitch recording higher E24 at 71.5 ± 0.03%. In conclusion, P. aeruginosa USM-AR2 was able to utilize agricultural wastes to produce appreciable amounts of rhamnolipid.