Abstract

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants, ubiquitously present and are hazardous to all forms of life due to their toxic, carcinogenic, and mutagenic nature. With enhanced understanding of adverse effects of PAHs on living organisms, reclamation of PAH-contaminated sites has become a global concern. In order to devise efficient bioremediation strategies for PAH-degradation, the identification and study of metabolic potential of microbial species is essential. The goal of this study is to isolate PAH-degrading bacterial strains from petroleum contaminated soil that can utilize PAHs as their sole carbon source and investigate their growth on medium containing PAHs as only carbon source. For the first time, the evolutionary relationship of isolated bacterial strains with known PAH-degrading bacterial strains having PAH-catabolic genes/enzymes involved in PAH-bioremediation was examined. Two strains isolated from contaminated soil, that is, Kocuria flava DTU-1Y and Rhodococcus pyridinivorans DTU-7P may have the ability to utilize PAHs as sole carbon source for their growth. Phylogenetic analysis for evolutionary relationship revealed that these strains are related to different known PAH-degrading bacterial strains which have catabolic genes/enzymes involved in degradation pathway. The bacterial strains reported in this study may also possess the genes responsible for PAH-degradation and can prove useful in devising sustainable bioremediation approach.

摘要

多环芳烃 (PAHs) 是一种持久性有机污染物，无处不在，由于其有毒、致癌和致突变的性质，对所有形式的生命都是有害的。随着对 PAHs 对生物体的不利影响的深入了解，PAH 污染场地的回收已成为全球关注的问题。为了设计有效的 PAH 降解生物修复策略，鉴定和研究微生物物种的代谢潜力是必不可少的。本研究的目的是从石油污染的土壤中分离出多环芳烃降解菌株，这些菌株可以利用多环芳烃作为其唯一碳源，并研究它们在含有多环芳烃作为唯一碳源的培养基上的生长情况。首次，检查了分离的细菌菌株与已知的具有 PAH 分解代谢基因/酶的 PAH 降解菌株的进化关系，这些基因/酶参与 PAH 生物修复。从污染土壤中分离出的两种菌株，即Kocuria flava DTU-1Y 和Rhodococcus pyridinivorans DTU-7P 可能具有利用 PAHs 作为其生长的唯一碳源的能力。进化关系的系统发育分析表明，这些菌株与不同的已知多环芳烃降解菌株有关，这些菌株具有参与降解途径的分解代谢基因/酶。本研究中报道的细菌菌株也可能具有负责 PAH 降解的基因，并且可以证明对设计可持续的生物修复方法很有用。