Production and viscosity of Xanthan gum are increased by LED irradiation of X. campestris cultivated in medium containing produced water of the oil industry

Abstract

Oil recovery is a challenge and microbial enhanced oil recovery is an option. We theorized that the use of produced water (PW) with photo-stimulation could influence both production and viscosity of Xanthan gum. This study aimed at the evaluation of the effect of photo-stimulation by λ630 ± 1 ηm LED light on the biosynthesis of Xanthan gum produced by Xanthomonas campestris IBSBF 2103 strain reusing PW of the oil industry. We assessed the effect of photo-stimulation by LED light (λ630 nm) on the biosynthesis of Xanthan gum produced by X. campestris in medium containing produced water. Different energy densities applied during the microbial growth phase were tested. The highest production was achieved when using 12 J/cm2 LED light (p<0.01). Three protocols were assessed: Non-irradiated (Control), Irradiation with LED light during the growth phase (LEDgrowth) and Irradiation with LED light during both growth and production phases (LED growth+production). Both the amount and viscosity of the xanthan gum was significantly higher (p<0.01) in the group LEDgrowth+production. The study showed that LED irradiation (λ630 ± 1 ηm) during both the growth and production phases of the biopolymer increased both the production and viscosity of Xanthan gum.