Surfactant/Alkali Stress Effect in Exopolysaccharide Production by Xanthomonas and Enterobacter Strains

New innovative technologies are required today for lowering the production costs of highly demanded microbial exopolysaccharides (EPS). The physiological “stress” caused by the presence of alkaline and non-cationic surfactants (Triton X-100) in the media (alone or in combination) may significantly increase Xanthomonas campestris and Enterobacter sp. Production of EPS. A mineral media (MSM) was supplemented with sucrose and crude glycerin (GB) and prepared with produced water either diluted (PW) or dialyzed (DPW) for removing mineral salts. Under conditions of alkaline stress (pH 9.5), the microbial population of X. campestris showed an increase in EPS production of 16.7% (p < 0.01). The addition of Triton X-100, however, increased the production and also the viscosity of the X. campestris EPS. On the other hand, this former substance was toxic to Enterobacter sp. in the lowest concentration tested (0.1%). The association of alkaline stress with Triton X-100 increased the production and quality of the EPS produced by X. campestris, with maximum values of 88.72% of production and 190.35% of viscosity in the medium prepared with DPW (P < 0.0001). The technology developed “surfactant/alkali stress” is an innovative way of reducing production costs and increasing the quality of EPS xanthan gum.