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Updated: Jan 12, 2026

Isolation, Propagation, and Identification of Bacterial Species with Hydrocarbon Metabolizing Properties from Aquatic Habitats
Published on: December 7, 2021
Preferential selection of toxic polyaromatic hydrocarbons and their intermediates by Pseudomonas fragi driven by
Ankita Das1, Sourav Debnath1, Anand Prakash Maurya1
1Soil and Environmental Microbiology Laboratory, Department of Microbiology, Assam University, Silchar, Assam 788011, India.
Abstract:
The extensive use of petroleum crude and its derivatives has caused widespread contamination by polycyclic aromatic hydrocarbons (PAHs), posing serious ecological and health risks. Bioremediation using microbial pathways offers a sustainable solution, yet microbial substrate preference and catabolite repression critically influence PAH degradation efficiency. This study examined the degradation of three high molecular weight PAHs, fluoranthene, pyrene, and benzo(a)pyrene by Pseudomonas fragi DBC, focusing on catechol 1,2-dioxygenase and catechol 2,3-dioxygenase. P. fragi DBC degraded 90-99 % of the PAHs within 28 days, with a marked initial preference for benzo(a)pyrene. Enzyme-substrate analyses revealed higher binding affinity of both dioxygenases for benzo(a)pyrene and its intermediates compared to other PAHs. Toxicity assessments showed that ligands with higher enzyme affinity were more toxic than their degradation products. qRT-PCR analysis indicated increased transcription of both dioxygenase genes in the presence of PAHs, highlighting the strain's enhanced catabolic potential for mineralizing a broad spectrum of PAH pollutants. These findings underscore the crucial role of enzyme-mediated substrate specificity in governing microbial degradation kinetics in complex environmental settings.
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