A Review of Pyrene Bioremediation Using Mycobacterium Strains in a Different Matrix

Polycyclic aromatic hydrocarbons are compounds with 2 or more benzene rings, and 16 of them have been classified as priority pollutants. Among them, pyrene has been found in higher concentrations than recommended, posing a threat to the ecosystem. Many bacterial strains have been identified as pyrene degraders. Most of them belong to Gram-positive strains such as Mycobacterium sp. and Rhodococcus sp. These strains were enriched and isolated from several sites contaminated with petroleum products, such as fuel stations. The bioremediation of pyrene via Mycobacterium strains is the main objective of this review. The scattered data on the degradation efficiency, formation of pyrene metabolites, bio-toxicity of pyrene and its metabolites, and proposed degradation pathways were collected in this work. The study revealed that most of the Mycobacterium strains were capable of degrading pyrene efficiently. The main metabolites of pyrene were 4,5-dihydroxy pyrene, phenanthrene-4,5-dicarboxylate, phthalic acid, and pyrene-4,5-dihydrodiol. Some metabolites showed positive results for the Ames mutagenicity prediction test, such as 1,2-phenanthrenedicarboxylic acid, 1-hydroxypyrene, 4,5-dihydropyrene, 4-phenanthrene-carboxylic acid, 3,4-dihydroxyphenanthrene, monohydroxy pyrene, and 9,10-phenanthrenequinone. However, 4-phenanthrol showed positive results for experimental and prediction tests. This study may contribute to enhancing the bioremediation of pyrene in a different matrix.

Automated summary

Polycyclic aromatic hydrocarbons, including pyrene, are priority pollutants due to their environmental effects. Bacterial strains, especially Mycobacterium and Rhodococcus, have been identified as efficient pyrene degraders. This review collected scattered data on degradation efficiency, metabolite formation, bio-toxicity, and proposed degradation pathways. Most Mycobacterium strains showed efficient degradation of pyrene, with 4,5-dihydroxy pyrene, phenanthrene-4,5-dicarboxylate, phthalic acid, and pyrene-4,5-dihydrodiol as the main metabolites. Some metabolites exhibited positive results in mutagenicity tests. This study contributes to the understanding and enhancement of pyrene bioremediation.