Different optimization conditions required for enhancing the biodegradation of linear alkylbenzosulfonate and sodium dodecyl sulfate surfactants by novel consortium of Acinetobacter calcoaceticus and Pantoea agglomerans

The anionic surfactants linear alkylbenzosulfonate (LAS) and sodium dodecyl sulfate (SDS) were degraded by a consortium of the mixed facultative anaerobes Acinetobacter calcoaceticus and Pantoea agglomerans which were isolated from wastewater. The growth of this consortium in nutrient broth medium at temperature of 30 degrees C; pH 8.5; and agitation rates of 250 rpm, was able to degrade high biomass of the two surfactants. Under these growth conditions a complete degradation of 4000ppm SDS biomass was achieved within 120h incubation time while a longer period (150 h) was capable of degrading only 60% of 300 ppm LAS biomass. However, a full degradation of LAS was accomplished by additional supplementation of the mixed culture with some carbon sources. Also, an alternative supplementation with nitrogen nutrients has increased the biodegradation extent of LAS from 60% to 90%. In contrast, such supplementation of the mixed culture with carbon and nitrogen nutrients had adverse effects on the induction of SDS degradation. Both surfactants at higher concentrations became toxic to the mixed co-culture bacteria particularly affecting the A. calcoaceticus strain of the consortium. The supplementation of either surfactant as sole carbon source to the mixed culture growing in minimal medium produced 10% degradation of SDS and 60% degradation of LAS, respectively. These data are discussed in terms of differences between the enzymic induction of LAS and SDS bacterial biodegradation. (c) 2007 Elsevier Inc. All rights reserved.