Biodegradation of Total Petroleum Hydrocarbons and EPA-16 PAHs in Crude Oil by Pseudomonas aeruginosa KUD2
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Date
2025
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Abstract
The complex mixture of hydrocarbons known as Speciated EPA-16 Polyaromatic
Hydrocarbons (PAHs), which are frequently found in crude oil and are known to be
extremely hazardous, mutagenic, carcinogenic, teratogenic, and immunotoxicogenic to
different life forms, is included in the category of Extractable Total Petroleum Hydrocarbons
(ETPHs), which also includes aliphatic compounds. Considering the environmental and
public health hazards linked to ETPHs and PAHs, there is a compelling need to explore
indigenous bacteria with the capability to efficiently degrade these contaminants. The
present study investigated the biodegradation potential of bacterial isolates from oilpolluted
soil, focusing on Extractable Total Petroleum Hydrocarbons (ETPHs) - Aliphatic
and Speciated EPA-16 Poly Aromatic Hydrocarbons (PAHs) in crude oil samples. In this
study, four predominant bacterial isolates, designated as KUD1, KUD2, KUD3, and KUD4,
were isolated from oil-contaminated soil obtained from Okrika in Rivers State, Nigeria.
These isolates exhibited positive outcomes in both the drop collapse and oil displacement
tests, affirming their biosurfactant-producing, surface tension-reducing, and oil-displacing
capabilities. Among them, KUD2 exhibited the highest emulsification index, highlighting
its proficiency in forming stable oil-in-water emulsions. Consequently, KUD2, owing to
its remarkable growth on agar plates containing 10% crude oil, was chosen for further
investigation. The highly efficient isolate, KUD2 identified as Pseudomonas aeruginosa
using 16S rDNA sequencing. The isolate exhibited enzymatic capabilities in the degradation
of hydrocarbons, with catechol-1,2-dioxygenase enzymes detected with varying activity
levels over time. Conversely, catechol-2,3-dioxygenase (C23O) remained consistently
inactive throughout the experiment, suggesting alternative metabolic pathways or a lack
of involvement in the studied biodegradation process. During the incubation period, the
pH fluctuations correlated with the highest enzyme production, suggesting metabolic
adaptations. Furthermore, P. aeruginosa KUD2 demonstrated significant increases in
Alkane hydroxylase and Alcohol dehydrogenase secretion, reaching peak production after
ten days of incubation signifying their active catalytic roles within the pathways associated
with the investigated biodegradation process. Mass chromatograms revealed the presence
of aromatic hydrocarbons in control crude oil samples, while KUD2 efficiently degraded
ETPHs, reducing their concentration. Likewise, KUD2 demonstrated effective degradation
of Speciated EPA-16 PAHs. The concentrations of aliphatic hydrocarbons in crude oil were
significantly reduced after degradation, with some compounds being entirely degraded.
Overall, this study underscores the potential of P. aeruginosa KUD2 for environmental
bioremediation, as it efficiently degrades hydrocarbons and highlights the enzyme dynamics
and pH influences in the biodegradation process.