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. 2017 Apr 28:15:1-10.
doi: 10.1016/j.btre.2017.04.002. eCollection 2017 Sep.

Comparative study on the degradation of dibutyl phthalate by two newly isolated Pseudomonas sp. V21b and Comamonas sp. 51F

Vinay Kumar  1 , Neha Sharma  2 , S S Maitra  1
Affiliations

Comparative study on the degradation of dibutyl phthalate by two newly isolated Pseudomonas sp. V21b and Comamonas sp. 51F

Vinay Kumar et al. Biotechnol Rep (Amst). .

Abstract

Dibutyl phthalate is (DBP) the top priority toxicant responsible for carcinogenicity, teratogenicity and endocrine disruption. This study demonstrates the DBP degradation capability of the two newly isolated bacteria from municipal solid waste leachate samples. The isolated bacteria were designated as Pseudomonas sp. V21b and Comamonas sp. 51F after scanning electron microscopy, transmission electron microscopy, Gram-staining, antibiotic sensitivity tests, biochemical characterization, 16S-rRNA gene identification and phylogenetic studies. They were able to grow on DBP, benzyl butyl phthalate, monobutyl phthalate, diisodecyl phthalate, dioctyl phthalate, and protocatechuate. It was observed that Pseudomonas sp. V21b was more efficient in DBP degradation when compared with Comamonas sp. 51F. It degraded 57% and 76% of the initial DBP in minimal salt medium and in DBP contaminated samples respectively. Kinetics for the effects of DBP concentration on Pseudomonas sp. V21b and Comamonas sp. 51F growth was also evaluated. Stoichiometry for DBP degradation and biomass formation were compared for both the isolates. Two major metabolites diethyl phthalate and monobutyl phthalates were identified using GC-MS in the extracts. Key genes were amplified from the genomes of Pseudomonas sp. V21b and Comamonas sp. 51F. DBP degradation pathway was also proposed.

Keywords: Degradation kinetics; Endocrine disruptors; Gene identification; Phthalate ester degradation; Stoichiometry.

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Figures

Fig. 1
Fig. 1
(a) Scanning electron micrograph of strain 21b. Scale bar 2 μm. (b) Scanning electron micrograph of strain 51F. Scale bar 2 μm.(c) Transmission electron micrograph of strain 21b. Scale bar 20 nm. (d) Transmission electron micrograph of strain 51F. Scale bar 100 nm.
Fig. 2
Fig. 2
(a) Phylogenetic tree of Pseudomonas sp. V21b. (b) Phylogenetic tree of Comamonas sp. 51F. The evolutionary history was inferred using the UPGMA method.
Fig. 3
Fig. 3
(a) Comparative growth of Pseudomonas sp. V21b and Comamonas sp. 51F. (b) Comparative degradation of DBP by Pseudomonas sp. V21b and Comamonas sp. 51F in MSM. (c) Comparative degradation of DBP by Pseudomonas sp. V21b and Comamonassp. 51F in DBP contaminated samples.
Fig. 4
Fig. 4
(a) DBP degradation kinetics of Pseudomonas sp. V21b. (b) DBP degradation kinetics of Comamonas sp. 51F.
Fig. 5
Fig. 5
DBP degradation metabolic intermediates identified by GC–MS. Structure and m/z ratio of the identified metabolic intermediates. M1- dibutyl phthalate, M2-diethyl phthalate, and M3-monobutyl phthalate.
Fig. 6
Fig. 6
Phthalate esters degrading genes amplified form the genomes of Pseudomonas sp. V21b and Comamonas sp. 51F. (a) Pseudomonas sp. V21b. (b) Comamonas sp. 51F. Ld-ladder, c-control, Oph-A1-17, 151, Oph-B-4, Oph-C-14, 154, Oph-D-16, 152, Tph-A2-9, Tph-A3-155 and Tph-B-155.
Fig. 7
Fig. 7
DBP degradation pathway based on the identified metabolic intermediates.
See this image and copyright information in PMC

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