Isolation,Identification And Degradation Characteristics Of Phthalic Acid Esters And Organophosphorus Flame Retardants Degrading Bacteria

There is an increasing concern about the release of aromatic pollutants into environment.This is because majority of anthropogenic pollutants are toxic to living organisms.Phthalic acid esters(PAEs)and Organophosphorus flame retardants(OPFRs)are the predominant environmental pollutants that have gained considerable attention because of their acute toxicity,wide distribution,and high persistence.Biodegradation is a powerful tool to remove these toxic compounds from the environment being safe and ecofriendly.Di-(2-ethylhexyl)phthalate(DEHP)is a type of phthalic acid esters commonly used as a plasticizer to endow polyvinyl chloride plastics with desirable physical properties.It is synthesized in massive amounts worldwide.Numerous studies highlighted its adverse effects of DEHP on human health and wildlife.In fact,DEHP is labeled as an endocrine disruptor causing human reproductive problems.In the present work,Enterobacter spp.YC-IL1,a novel strain isolated from contaminated soil in Mila province,Algeria,was identified by 16 S r RNA gene analysis and electronic microscope.This strain is capable of degrading DEHP(100%)efficiently along with a wide range of phthalic acid esters,particularly those containing branched side chains or those bearing ring structures such as butylbenzyl phthalate and dicyclohexyl phthalate.Though optimal activity of DEHP biodegradation was at p H of 7.0,YC-IL1 maintained a considerable activity at lower p H of 5 suggesting its acido-tolerant nature.Strain YC-IL1 showed high DEHP degradation rate in artificially contaminated soil with 86% removed in 6 days.These findings suggest that this strain has the potential to be used in bioremediation of PAE-polluted sites,even under the acidic conditions.On the other hand,Organophosphorus flame retardants are produced in a massive amount worldwide.They serve as plasticizers and flame retardants in many industrial and consumer products such as plastic items,electronics and automobile supplies,flooring and building materials,though many studies highlighted their potential toxicity towards human and wildlife.Two bacterial consortia,namely YC-ML1 and YC-CHW1,were enriched from Mila province in Algeria and Beijing province in china,respectively.Both consortia exhibited excellent degradation ability towards TPh P with 92.6% and 95.3%,respectively,in four days of treatment.However,trials to isolate bacterial strain capable of degrading TPh P independently were fruitless.Both consortia grew on tricresyl phosphate,2-ethylhexyl diphenyl phosphate,and tris(2-ethylhexyl)phosphate containing media and efficiently degrade them with 98.19%,98.5% and 84.78 % for YC-ML1,and 92.78% 91.63% and 74.53% for YC-CHW1,respectively.These consortia effectively workout under a wide range of temperature(20–40°C),p H(6.0–10.0)and salinity(0–4%)with the optimum degradation was at 30°C,p H=7 and 0% Na Cl for both of them.The analysis of 16 S r DNA diversity indicated that the two consortia harbor different bacterial composition.