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 × 10 ⁴ MPN/g (σ=3.4 × 10 ⁴ MPN/g) and 2.4 % (σ= 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.