Affiliation:
1. FEST Division, Environmental Toxicology Group, CSIR-Indian Institute of Toxicology Research , Lucknow 226001, Uttar Pradesh , India
2. Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002, Uttar Pradesh , India
3. Analytical Sciences and Accredited Testing Services, CSIR-Indian Institute of Toxicology Research , Lucknow 226001, Uttar Pradesh , India
Abstract
Abstract
Aims
Isolation of phthalate esters (PAEs) degrading bacteria from a solid waste dumpsite could degrade many plasticizers efficiently and to investigate their degrading kinetics, pathways, and genes.
Methods and results
Based on their 16S rRNA gene sequence the strains were identified as Dietzia kunjamensis IITR165 and Brucella intermedia IITR166, which showed a first-order degradation kinetic model under lab conditions. The quantification of phthalates and their intermediate metabolites identification were done by using ultra-high-performance liquid chromatography (UHPLC) and gas chromatography-tandem mass-spectrometry (GC-MS/MS), respectively. Both the bacteria utilized >99% dibutyl phthalate at a high concentration of 100-400 mg L−1 within 192 h as monitored by UHPLC. GC-MS/MS revealed the presence of metabolites dimethyl phthalate (DMP), phthalic acid (PA), and benzoic acid (BA) during DBP degradation by IITR165 while monobutyl phthalate (MBP) and PA were identified in IITR166. Phthalate esters degrading gene cluster in IITR165 comprised two novel genes coding for carboxylesterase (dkca1) and mono-alkyl phthalate hydrolase (maph), having only 37.47% and 47.74% homology, respectively, with reported phthalate degradation genes, along with the terephthalate dioxygenase system (tphA1, A2, A3, and B). However, IITR166 harbored different gene clusters comprising di-alkyl phthalate hydrolase (dph_bi), and phthalate dioxygenase (ophA, B, and C) genes.
Conclusions
Two novel bacterial strains, Dietzia kunjamensis IITR165 and Brucella intermedia IITR166, were isolated and found to efficiently degrade DBP at high concentrations. The degradation followed first-order kinetics, and both strains exhibited a removal efficiency of over 99%. Metabolite analysis revealed that both bacteria utilized de-methylation, de-esterification, and decarboxylation steps during degradation.
Funder
S.S.
R.S.T.
Council of Scientific and Industrial Research, India
University Grants Commission India
Publisher
Oxford University Press (OUP)
Subject
Applied Microbiology and Biotechnology,General Medicine,Biotechnology