Abstract

With heptachlor as the sole carbon source, an effective heptachlor-degrading microorganism (named strain H) was isolated from the sludge of heptachlor-polluted sewage of a chemical plant, via enrichment, screening and purification. Strain H was identified as a facultative anaerobic Gram-negative bacterial strain belonging to genus Shigella based on the physiological-biochemical characteristics and the similarity analysis of its 16S rDNA gene sequence with the sequences logged in the Ribosomal Database Project and GenBank databases. When the optimal inoculation volume and the pH were 20% and 7.1–7.6, respectively, strain H was able to degrade heptachlor by more than 88.2% after130 h, with initial concentration of heptachlor being 300 μg/L at 30 ± 0.5 °C. It was also shown that strain H can grow on the degradation products of heptachlor such as 1-hydroxychlordene or heptachlor epoxide. Furthermore, additional carbon sources can accelerate the degradation rate of heptachlor because of co-metabolism. The degradation dynamics could be described by a first-order reaction model. A real-world field experiment demonstrated that strain H was effective in practical applications of heptachlor biodegradation in contaminated soil.

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