Effect of manganese and ferric ions on the degradation of DI-2-ethylhexyl phthalate (DEHP) by acinetobacter SP. SN13
de Toledo R.A.; Xu J.; Chao U.H.; Shim H.
Source PublicationMicropollutants: Sources, Ecotoxicological Effects and Control Strategies
PublisherNova Science Publishers, Inc.

Phthalate esters (PAEs) are artificially synthetized organic compounds extensively used as plasticizers for industrial, medical, and domestic purposes. Di(2-ethylhexyl) phthalate (DEHP) is one of the most synthetized PAEs and is considered resistant to the biological degradation due to its long hydrocarbon chain. An indigenous microorganism was isolated from the sludge collected from a local wastewater treatment plant (Macau SAR, China) to remove DEHP from artificially contaminated water. The 16S rRNA gene sequence analysis identified the microbial strain as Acinetobacter sp. SN13. Such major experimental parameters as pH (6-9) and temperature (35°C) were further optimized to improve the DEHP biodegradation efficiency. The growth kinetics followed the inhibition model (simulated using Matlab), with half saturation constant (272.3 mg l-1), maximum degradation rate (124.8 mg l-1 day-1), and inhibition constant (720.5 mg l-1) estimated for the DEHP degradation, and half saturation constant (137.6 mg l-1), specific growth rate (0.1192 day-1), and inhibition constant (850.3 mg l-1) for the microbial growth on DEHP. Since many environmental sites are contaminated with a mixture of inorganic and organic contaminants, the effect (inhibitory/stimulatory) of some microelements commonly present in wastewater (Fe3+ and Mn2+) on DEHP biodegradation was also evaluated. The biodegradation performance of the isolate was improved as the Fe3+ concentration increased (100-1,000 µg l-1), while higher Mn2+ concentrations (500- 1,000 µg l-1) inhibited the DEHP biodegradation. The aerobic biodegradation of phthalates generally occurs in two stages. First, phthalate diesters (PDEs) hydrolyze to phthalate monoesters (PMEs) followed by the PMEs hydrolysis to phthalic acid (PA) and then, the PA mineralization takes place by different mechanisms. For the Gramnegative bacteria like Acinetobacter sp., PA is usually further degraded via the dioxygenase-catalyzed pathways to protocatechuate (3,4- dihydroxy-benzoate) through 4,5-dihydroxyphthalate and cis-4,5- dihydroxy-4,5-dihydrophthalate. The respective DEHP degradation pathway for Acinetobacter sp. SN13 is proposed through the identification of mono-(2-ethylhexyl) phthalate (MEHP), PA, 3- katoadipate, β-carboxy-cis, cis-muconic acid, and protocatechuate by LCMS.

KeywordAcinetobacter Sp. Biodegradation Pathway Di(2-ethylhexyl) Phthalate Growth Kinetics Microelements
URLView the original
Fulltext Access
Document TypeBook chapter
AffiliationDepartment of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, Macau
First Author AffilicationFaculty of Science and Technology
Recommended Citation
GB/T 7714
de Toledo R.A.,Xu J.,Chao U.H.,et al. Effect of manganese and ferric ions on the degradation of DI-2-ethylhexyl phthalate (DEHP) by acinetobacter SP. SN13:Nova Science Publishers, Inc.,2017:45-67.
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