Influence of Produced Water and Light Irradiation on the Composition of Exopolysaccharide Produced by <scp><i>L. amnigena</i></scp> Evaluated by Raman Spectroscopy

This study aimed to compare the changes in the composition of the exopolysaccharide (EPS) produced by Lelliottia amnigena in culture medium containing distilled water (DW) and dialyzed produced water (DPW) irradiated by either Laser (λ660 nm, 8.0 J/cm²) or LED (λ630 nm, 12.0 J/cm²) during bacterial growth using Raman spectroscopy at 1064 nm. The cultures of L. amnigena were irradiated at 9- and 12-h, and the EPS obtained from different production protocols were analyzed dehydrated. Raman spectra showed peaks assigned to saccharides from EPS polymer, and principal component analysis revealed differences in the composition of the EPS produced depending on the water used in production and the light source used for irradiation. Remarkably, the presence of acyl groups (acetyl and pyruvyl) in the mannose residues at the group DW and mannose without evidence of acetyl in the irradiated groups; the irradiated groups also presented evidence of carboxylate (succinyl).