Application of alkyl polyglycosides for enhanced bioremediation of petroleum hydrocarbon-contaminated soil using Sphingomonas changbaiensis and Pseudomonas stutzeri

Abstract

Bioremediation is considered a cost-effective and environmentally sound method for degradation of petroleum hydrocarbons in contaminated soils. This study investigated the effects of biosurfactant alkyl polyglycosides (APG) on enhanced biodegradation of petroleum hydrocarbon-contaminated soils using Sphingomonas changbaiensis and Pseudomonas stutzeri and explored the mechanism responsible for the enhanced petroleum hydrocarbon degradation. To accomplish this, the following treatments were evaluated: (1) bioaugmentation with Sphingomonas changbaiensis; (2) bioaugmentation with Pseudomonas stutzeri; (3) a combination of Sphingomonas changbaiensis and APG; and (4) a combination of Pseudomonas stutzeri and APG. The results showed that the degradation rates of total petroleum hydrocarbons (TPH) in contaminated soil samples bioaugmented with S. changbaiensis and P. stutzeri for 30 days were 39.2 ± 1.9% and 47.2 ± 1.2%, respectively. The addition of biosurfactant APG enhanced the bioremediation processes and improved the biodegradation rates. The biodegradation rate at 1.5 g/kg APG in soil samples bioaugmented with S. changbaiensis was 52.1 ± 2.0%, while the rate at 1.5 g/kg APG in soil samples bioaugmented with P. stutzeri was 59.0 ± 1.8%. The half-life decreased from 39.7 d to 24.5 d and from 29.6 to 20.1 d when the dosage of APG was 1.5 g/kg in contaminated soil samples bioaugmented with S. changbaiensis and P. stutzeri, respectively. Mechanism studies showed that the addition of APG can increase the TPH solubility, promote the sorption of TPH onto microbial cells and subsequent trans-membrane transport by APG-induced structural changes, stimulate microbial activities and participate in the co-metabolism. Therefore, the combination of bioaugmentation and APG is an effective method for remediation of petroleum hydrocarbon-contaminated soil.