Biodegradation of di-n-butylphthalate and phthalic acid by a novel Providencia sp 2D and its stimulation in a compost-amended soil

A novel 2D strain that could effectively degrade di-n-butylphthalate (DBP) and its major metabolite, phthalic acid (PA), was isolated from compost and identified as Providencia sp. 2D. A complete degradation of DBP (200 mg L-1) was observed within 3 days under optimal conditions obtained by response surface methodology. This strain 2D could utilize various phthalic acid esters (PAEs) as substrates for growth, and could co-metabolize DBP in the presence of extra C sources. A novel combination of two common pathways in PA degradation was proposed for DBP degradation pathway, representing the first report of two ring cleavage pathways of the intermediate PA in a microbial species. Strain 2D efficiently enhanced the removal rate of DBP in contaminated soil with a sharp decrease of the DBP half-life compared to non-bioaugmentation treatments. Moreover, the addition of compost improved the degradation rate of DBP in soil by stimulating microbial activity. The results support the feasibility of remediating DBP-contaminated soils inoculated with strain 2D and treated with compost.