The current study is aimed to evaluate the mechanism of anthracene degradation by a bacterial strain isolated from fly ash deposition site near Jamadoba Coal Preparation Plant, Jharkhand, India. The Bushnell-Haas media cultured (containing anthracene as sole carbon source) bacterial isolate was identified by 16S rRNA gene sequence coding as the Bacillus thuringiensis strain, which showed the efficiency to degrade anthracene. The degradation efficiency of the strain has been estimated to be around 91% (for 40 mg l-1 of anthracene concentration) after 2 weeks of incubation at 33-36°C and initial pH of 6·8-7. The growth kinetics of the isolated strain has been described well by the Haldane-Andrews model of microbial growth pattern for inhibitory substrate, with a correlation factor (R2 value) of 0·9790. The maximum specific growth rate (μmax ) was 0·01053 h-1 and the value of inhibition coefficient for Haldane model was specified as 18·2448 mg l-1 . In the present study, some diphenol metabolites were identified besides the known possible biodegradation products.
Significance and impact of the study: Polycyclic aromatic hydrocarbons (PAHs) are recognized as significant health risks and consequently listed as priority pollutants by environmental protection agencies across the globe. The aim of the present study was to degrade one of the important PAHs, anthracene, by a newly isolated Bacillus thuringiensis strain. This is the first report of anthracene degradation by B. thuringiensis. This is also the very first growth kinetic study of a bacteria in an anthracene-containing medium. Some diphenol metabolites were found for the first time as anthracene biodegradation by-products, which can be an indication towards a new pathway.
Keywords: Bacillus thuringiensis; anthracene; biodegradation; diphenol metabolite; growth kinetics.
© 2017 The Society for Applied Microbiology.