Mechanisms Used by Bacteria in the Removal of Oil Pollutants: An Overview

Abstract

Oil pollution poses a serious environmental threat, particularly due to the toxic and persistent nature of petroleum hydrocarbons. Microbial bioremediation, especially using bacteria, is an eco-friendly and cost-effective strategy to degrade oil pollutants in contaminated environments. Bacteria utilize specialized metabolic pathways to break down hydrocarbons. This research was aimed to outline the mechanisms used by bacteria in the removal of oil pollutants. The degradation process generally follows these stages: emulsification by bio-surfactants, adsorption onto bacterial cells, cellular uptake, and enzymatic breakdown. Enzymes like alkane hydroxylases and catechol dioxygenases convert complex hydrocarbons into simpler, non-toxic compounds such as carbon dioxide and water. Five major microbial degradation pathways for hydrocarbons were discussed: terminal, sub-terminal, di-terminal oxidation, the Finnerty pathway, and degradation of aromatic hydrocarbons. The degradation mechanisms vary based on the structure of the pollutant—straight-chain alkanes, cyclic compounds, or polycyclic aromatic hydrocarbons (PAHs). The efficiency of microbial degradation is influenced by factors such as temperature, oxygen, nutrient availability, oil composition, and microbial community dynamics. Techniques like bio-stimulation (nutrient enhancement) and bio-augmentation (adding effective microbial strains) greatly improve biodegradation performance. Beyond biological methods, physical and chemical remediation techniques—like flotation, incineration, chemical oxidation, and surfactants—are explored. However, these are often expensive, energy-intensive, and less sustainable compared to microbial methods. Enzymes are central to microbial oil degradation, and bacterial adaptability is often enhanced through horizontal gene transfer, enabling better pollutant breakdown. Aerobic and anaerobic degradation pathways allow for flexibility under varying environmental conditions. Ultimately, microbial degradation offers a promising solution to oil pollution, and further advancement through genetic engineering, process optimization, and integration of biotechnologies could enhance its effectiveness.

Keywords: Mechanisms, Bacteria, Oil-Pollutants, Degradation