Studies On Biodegradation Characteristic Of DEHP By Newly Isolated Ochrobactrum Sp. Strain L1-W

Phthalates are large family of chemical compounds used as plasticizers to improve flexibility,softening,durability of various daily items.Among phthalates,DEHP is the most widely used phthalate.It is primarily used for the manufacturing of products made of PVC.DEHP is also used to make shoes,shower curtain,medical devices,clothes,bedding,gelling agents,packaging,building materials,binders and children toys.Despite being so useful,its exposure results in many adverse health effects.DEHP is an endocrine disrupting hormone that interferes with normal physiology of organisms.It has been reported to cause reproductive,respiratory,developmental defects in not only in humans but also in other animals.Both hydrolysis and photolysis have been found to be ineffective to remove DEHP from contaminated environment,leaving biodegradation as the most effective and reliable method to eliminate it and remediate the environment.This study aimed at isolation and characterization of highly efficient bacterium capable of degrading DEHP and uses it as sole carbon source.Soil and water samples were collected from Southlake(Nanhu)and processed in our laboratory.Strain L1-W was isolated and characterized morphologically,physiologically and using 16S rDNA sequencing.Based on the results,isolate L1-W was classified in the genus of Ochromobatrum sp.Its optimum degradation was best recorded when the temperature,pH and concentration were 30℃ 6.0 and 400 mg/l.Furthermore,Ll-W showed a strong ability to withstand high salinity content up to 10%of salt concentration making it one of the excellent candidates to remediate a salty environment without additional cost of desalination.Besides,L1-W proved to have a broad range to use other phthalates such as Benzyl butyl phthalate,Di-butyl phthalate,Di-methyl phthalate,Dioctyl phthalate and Di-ethyl Phthalate as sole source of carbon.Degradation kinetics of DEHP by Ochrobactrum sp.L1-W followed the first order equation with the half-live of 11.3 hours when the initial concentration was 200 mg/l and 98.7%of DEHP was degraded under the above optimum conditions.According to these findings,strain Ochrobactrum antropi L1-W could be used to remove DEHP from contaminated environment and restore natural conditions.