Biofilm communities and biodegradation within permeable reactive barriers at fuel spill sites in Antarctica

Determining the composition of the complex microbial communities within biofilms can aid us in understanding the potential for biodegradation on different permeable reactive barrier materials. Microbial communities were examined under Antarctic conditions across laboratory and field studies using amplicon pyrosequencing, and the reaction of these communities to petroleum hydrocarbon contamination and NH4+ supplementation was assessed. Putative hydrocarbon degrading bacteria in the orders Actinomycetales and Burkholderiales were identified in laboratory flow cells and within the upper PRB and lower PRB at Casey Station, Antarctica. The release of NH4+ from ammonium exchanged zeolite was shown to reduce the microbial diversity of biofilms, when compared to natural zeolite. Bacteria from the orders Sphingomonadales, Rhodocyclales, Pseudomonadales and Xanthomonadales were also observed across the Zeopro™/granular activated carbon permeable reactive barrier mixtures. The bacterial species were observed within a uniform microbial biofilm layer, embedded within extracellular polymeric substances on the surface of the materials. This study demonstrates that petroleum hydrocarbon contamination can contribute to the enrichment of certain hydrocarbon degrading species on permeable reactive barrier materials.