Petroleum hydrocarbons represent the most frequent environmental contaminant.
The introduction of petroleum hydrocarbons into a pristine environment immediately changes
the nature of that environment, resulting in reduced ecosystem functionality. Natural attenuation
represents the single, most important biological process which removes petroleum hydrocarbons
from the environment. It is a process where microorganisms present at the site degrade the organic
contaminants without the input of external bioremediation enhancers (i.e., electron donors, electron
acceptors, other microorganisms or nutrients). So successful is this natural attenuation process that in
environmental biotechnology, bioremediation has developed steadily over the past 50 years based
on this natural biodegradation process. Bioremediation is recognized as the most environmentally
friendly remediation approach for the removal of petroleum hydrocarbons from an environment
as it does not require intensive chemical, mechanical, and costly interventions. However, it is
under-utilized as a commercial remediation strategy due to incomplete hydrocarbon catabolism and
lengthy remediation times when compared with rival technologies. This review aims to describe the
fate of petroleum hydrocarbons in the environment and discuss their interactions with abiotic and
biotic components of the environment under both aerobic and anaerobic conditions. Furthermore,
the mechanisms for dealing with petroleum hydrocarbon contamination in the environment will
be examined. When petroleum hydrocarbons contaminate land, they start to interact with its
surrounding, including physical (dispersion), physiochemical (evaporation, dissolution, sorption),
chemical (photo-oxidation, auto-oxidation), and biological (plant and microbial catabolism of
hydrocarbons) interactions. As microorganism (including bacteria and fungi) play an important
role in the degradation of petroleum hydrocarbons, investigations into the microbial communities
within contaminated soils is essential for any bioremediation project. This review highlights the
fate of petroleum hydrocarbons in tertial environments, as well as the contributions of different
microbial consortia for optimum petroleum hydrocarbon bioremediation potential. The impact of
high-throughput metagenomic sequencing in determining the underlying degradation mechanisms is
also discussed. This knowledge will aid the development of more efficient, cost-effective commercial
bioremediation technologies. |
