Enhanced Degradation of a Model Oil Compound in Soil Using a Liquid Foam-Microbe Formulation

Abstract

This paper describes the development of a protein-based foam formulation and subsequent investigations into its suitability to enhance the degradation of a model hydrocarbon ( n -hexadecane) using novel bench-scale soil microcosms. High-density protein-based foam concentrates based upon those developed by the fire-fighting industry were selected for experimental investigation. Using crude protein hydrolysate as a starting material, a foam formulation was developed with properties suitable for bioremediation studies. This formulation incorporated eight hydrocarbon-degrading bacteria that had been selected for their ability to degrade hexadecane. In addition to their ability to utilize n -hexadecane, the bacteria were tested for compatibility with the foam formulation and each other. Seven individual Acinetobacter spp. and a Pseudomonas species were selected for use in the consortium based on these criteria. The use of this “bioactive foam” led to enhanced n -hexadecane degradation when compared to controls without foam. Following 7-d incubation, 60% of the n -hexadecane remained in the soil column using a foamed formulation, as compared to 90% with a nonfoamed control. In a subsequent experiment over a 15-d time course, the authors observed significantly greater n -hexadecane degradation in response to oxygenated bioactive foam treatment.