Abstract:
The dissolution and degradation of higher ring-number polycyclic aromatic compounds were tested in
batch and attached growth medium using soil biopile and fixed-film bioreactor systems. Bioavailability of
polycyclic aromatic hydrocarbons (PAHs) decreases with increasing ring-number. This means high ringnumber
compounds will survive longer in the environment and will therefore have a longer-term impact. In
the current study, pyrene and fluoranthene were degraded using a biosurfactant producing culture of
Pseudomonas aeruginosa grown in fixed-bed and soil biopile experiments. High ring-number PAHs prove
to be recalcitrant in nature due to their hydrophobicity and poor partitioning to soil media fixed biomass in
biofilm reactors. The use of biosurfactant could facilitate faster dissolution of the PAH and thus would
increase bioavailability of the PAH compounds to PAH degrading bacteria. The culture used in this study
was obtained from engine oil contaminated soil, that grow on HMW PAHs and are capable of degrading
PAHs were enriched, isolated and characterize. The isolated microbial cultures were further characterised
16S rDNA gene sequencing and genotype fingerprinting. During baseline study, over 90 % fluoranthene
was degraded as a model compound in biofilm reactor system. Over 88 % pyrene was degraded in soil
biopiles. In both cases, increased biosurfactant dose improved degradation rate up to the point where the
PAH concentration became inhibitory to biomass growth and PAH degradation.
