Phycoremediation of crude oil-contaminated water: Current microbial remediation protocol and effect on the ecosystem: A review

Abstract

Owing to the extensive use of petroleum hydrocarbons in the modern world, petrochemi
cal derivatives have become one of the major environmental pollutants with ensuing envi
ronmental devastation. Pollution of aquatic environments by hydrocarbon via numerous 
anthropogenic and natural sources has become even more worrisome. The detrimental 
effects of this pollution on the aquatic micro and macroorganisms, including fishes, birds, 
and mammals, have been thoroughly documented. The associated health impacts of crude 
oil pollution on humans and the environment have resulted in the current microbial reme
diation protocol to alleviate the effect on the ecosystem. The physicochemical protocols 
of cleaning the aquatic environments of hydrocarbon pollutants have been found deficient 
because of the high cost and the need for high-tech equipment and expertise. The ability of 
diverse microorganisms to degrade hydrocarbon pollutants as sources of carbon has been 
well studied for over three decades. These studies have focused mostly on bacteria. The 
bacterial-based crude oil remediation protocol is an effective means of remediating crude 
oil-polluted environments. It is environmentally friendly and cost-effective. It is even more 
effective when in collaboration with different species of bacteria (consortium) or when in 
association with plants (rhizodegradation). However, bacterial-based metabolism of organic 
pollutants, like crude oil, comes with severe reduction in dissolved oxygen, giving rise to 
longer time for microbial adaptation to the pollutants and the actual degradation, thus rais
ing questions on the application of bacterial-based remediation protocols. Studies on the 
hydrocarbon metabolism by algae are already available with some details on the oxygenic 
metabolic pathways. The present review, therefore, highlights the potentials/advantages of 
algae in crude oil remediation. In addition to algae’s direct involvement in the breakdown 
of hydrocarbon pollutants, it provides an enabling environment, like the copious supply of 
oxygen, for indigenous aerobic microbes equally involved in the remediation.