Achromobacter denitrificans strain SP1 efficiently remediates di(2-ethylhexyl)phthalate

This study describes how Achromobacter denitrificans strain SP1, a novel isolate from heavily plastics-contaminated sewage sludge efficiently consumed the hazardous plasticizer, di(2-ethylhexyl)phthalate (DEHP) as carbon source supplemented in a simple basal salt medium (BSM). Response surface methodology was employed for the statistical optimization of the process parameters such as temperature (32°C), agitation (200 rpm), DEHP concentration (10 mM), time (72 h) and pH (8.0). At these optimized conditions, experimentally observed DEHP degradation was 63%, while the predicted value was 59.2%; and the correlation coefficient between them was 0.998, i.e., highly significant and fit to the predicted model. Employing GC-MS analysis, the degradation pathway was partially deduced with intermediates such as mono(2-ethylhexyl)phthalate and 2-ethyl hexanol. Briefly, this first report describes A. denitrificans strain SP1 as a highly efficient bacterium for completely remediating the hazardous DEHP (10 mM) in 96 h in BSM (50% consumed in 60 h), which offers great potentials for efficiently cleaning the DEHP-contaminated environments such as soil, sediments and water upon its deployment.