Study into biodegradation of cocamidopropyl betaine, an amphoteric surfactant, by Pseudomonas bacteria and activated sludge

Abstract

Abstract: The paper examines the biodegradation rate of cocamidopropyl betaine by bacteria of the genus Pseudomonas and activated sludge. The following microorganisms were taken as destructor strains: Pseudomonas fluorescens TR (VKPM B-4881), Pseudomonas putida TP-19 (B-6582), Pseudomonas stutzeri T (B-4904), Pseudomonas putida TSh-18 (B-2950), Pseudomonas putida TO (B-3959), Pseudomonas mendocina 2S (B-4710), Pseudomonas oleovorans TF4-1L (B-8621) and activated sludge obtained at activated sludge reactors of a Kuzbass plant. Biooxidation of surfactant samples was carried out in 250 cm3 glass flasks, placed into an incubator shaker, at a constant temperature of 30ºС for pure cultures and 18ºС for activated sludge. The destructor strain should reduce the surfactant concentration to safe values within a minimum time interval. Pseudomonas stutzeri T (B-4904) and Pseudomonas fluorescens TR (B-4881) strains provided the shortest half-life of the surfactant under study – 2.5 and 2.6 days, respectively. For Pseudomonas putida TO (B-3959), Pseudomonas putida TSh-18 (B-2950) and Pseudomonas oleovorans TF4-1L (B-8621) strains, these values amounted to 3.0, 4.5 and 4.9 days, respectively. The maximum half-life of the surfactant under study was demonstrated by Pseudomonas mendocina 2S (B-4710) and Pseudomonas putida TP-19 (B-6582) microorganisms – 5.5 and 6.0 days, respectively. The maximum biodegradation of the surfactant was observed under its exposure to the biocenosis of microorganisms. Over 14 days, the concentration of cocamidopropyl betaine decreased to 0.27% of its initial concentration. The efficiency of Pseudomonas bacteria as destructors of surfactants was demonstrated. Bacteria of this genus exhibit a shorter generation time and a higher rate of biomass growth when compared to other strains and a shorter period of adaptation to surfactants when compared to activated sludge. Capable of reducing surfactant concentrations to safe values in a minimum time interval, Pseudomonas strains can be used as an effective agent in the development of technologies for wastewater purification from amphoteric surfactants.