Characterizing JP-5 Biodegradation Potential in Hawaii Soil Microbiome: Phylogeny, Growth Kinetics, and Biosurfactant Production

Soil and groundwater contamination from petroleum spills continues to present major environmental and human health challenges. A recent fuel contamination event in the Pearl Harbor region of the Island of Oahu, Hawaii, highlights the need for a better understanding of the biodegradation capabilities of the indigenous soil microbiome and potential for bioremediation. Soil sampling and subsequent cultivation-based enumeration showed that the abundance and relative abundance of JP-5 degrading bacterial biomass to be 1.9 x 104 MPN/g ({sigma}=3.4 x 104 MPN/g) and 2.4 % ({sigma}= 4.4 %), respectively. Isolation and 16S rRNA gene sequencing showed diverse phylogenetic groups of JP-5 degrading bacteria, including Achromobacter, Ralstonia, Stenotrophomonas, Pseudomonas, Acinetobacter, Staphylococcus, Bacillus, and Gordonia. Logistic modeling of batch growth experiments revealed significant variation in growth kinetic parameters amongst the soil bacterial isolates. Biosurfactant production by the JP-5-degrading bacterial isolates showed significant correlation with maximum optical density (r = 0.69, p < 0.001), relative growth rate (r = 0.41, p = 0.008), and relative lag phase duration (r = -0.36, p = 0.02), indicating an important role of biosurfactant production in enhancing hydrocarbon bioavailability. The results revealed the ubiquitous presence and phylogenetic diversity of JP-5 degrading microbial capabilities in the Hawaii soil microbiome and their potentials for bioremediation applications.