Bacterial degradation of phthalate isomers and their esters

Abstract

Phthalate isomers and their esters are used heavily in various industries. Excess use and leaching from the product pose them as major pollutants. These chemicals are toxic, teratogenic, mutagenic and carcinogenic in nature. Various aspects like toxicity, diversity in the aerobic bacterial degradation, enzymes and genetic organization of the metabolic pathways from various bacterial strains are reviewed here. Degradation of these esters proceeds by the action of esterases to form phthalate isomers, which are converted to dihydroxylated intermediates by specifi c and inducible phthalate isomer dioxygenases. Metabolic pathways of phthalate isomers converge at 3,4-dihydroxybenzoic acid, which undergoes either ortho-or meta-ring cleavage and subsequently metabolized to the central carbon pathway intermediates. The genes involved in the degradation are arranged in operons present either on plasmid or chromosome or both, and induced by specifi c phthalate isomer. Understanding metabolic pathways, diversity and their genetic regulation may help in constructing bacterial strains through genetic engineering approach for effective bioremediation and environmental clean up.

Biodegradation of phenanthrene by Pseudomonas sp. strain PPD: purification and characterization of 1-hydroxy-2-naphthoic acid dioxygenase

“…Phenanthrene-grown cells failed to show O 2 uptake with phthalic acid, although it is one of the proposed intermediate metabolites. This could be due to the inability of phenanthrene or intracellular phthalic acid to induce phthalic acid permease, which is responsible for phthalic acid uptake (Chang & Zylstra, 1999;Vamsee-Krishna & Phale, 2008).…”

Carbon source-dependent modulation of NADP-glutamate dehydrogenases in isophthalate-degrading Pseudomonas aeruginosa strain PP4, Pseudomonas strain PPD and Acinetobacter lwoffii strain ISP4

“…With respect to phthalate isomers, the metabolic pathways and enzymes involved in the degradation of phthalate and terephthalate have been studied in greater detail than those of isophthalate (Chatterjee & Dutta, 2003;Eaton, 2001;Eaton & Ribbons, 1982;Keyser et al, 1976;Phale et al, 2007;Quan et al, 2005;Shigematsu et al, 2003;Vamsee-Krishna et al, 2006;Vamsee-Krishna & Phale, 2008;Wang et al, 1995Wang et al, , 2003. There are very few reports that describe the utilization of all three phthalate isomers as the carbon source by a single microbial strain (Vamsee-Krishna et al, 2006;Vamsee-Krishna & Phale, 2008;Wang et al, 1995).…”

“…With respect to phthalate isomers, the metabolic pathways and enzymes involved in the degradation of phthalate and terephthalate have been studied in greater detail than those of isophthalate (Chatterjee & Dutta, 2003;Eaton, 2001;Eaton & Ribbons, 1982;Keyser et al, 1976;Phale et al, 2007;Quan et al, 2005;Shigematsu et al, 2003;Vamsee-Krishna et al, 2006;Vamsee-Krishna & Phale, 2008;Wang et al, 1995Wang et al, , 2003. There are very few reports that describe the utilization of all three phthalate isomers as the carbon source by a single microbial strain (Vamsee-Krishna et al, 2006;Vamsee-Krishna & Phale, 2008;Wang et al, 1995). The first key step involved in the bacterial degradation of phthalate isomers is the double hydroxylation of the aromatic ring by the respective phthalate dioxygenase to yield a cis-dihydrodiol intermediate, which is further metabolized to aliphatic intermediates of the central carbon cycle via 3,4-dihydroxybenzoate (3,4-DHB) (Ballou & Batie, 1988;Batie et al, 1987;Schlafli et al, 1994;Tarasev & Ballou, 2005;Vamsee-Krishna et al, 2006).…”

Bypassing Isophthalate Inhibition by Modulating Glutamate Dehydrogenase (GDH): Purification and Kinetic Characterization of NADP-GDHs from Isophthalate-Degrading Pseudomonas aeruginosa Strain PP4 and Acinetobacter lwoffii Strain ISP4

“…Due to the persistence of these compounds in the environment, microorganisms have evolved and adapted to utilize them as sole sources of carbon and energy. Compared to the organisms whose metabolic pathways for isophthalate degradation have been studied, a large number of organisms have been studied in detail to determine their metabolic pathways for phthalate and terephthalate degradation (12,17,18,20,25,26,29,31,32,35,36). The fewer isophthalate-degrading strains and the difficulties in isolating them could be due to the fact that isophthalate acts as a competitive inhibitor of glutamate dehydrogenase (GDH), which plays an important role at the interface of C metabolism and N metabolism (5,11,13,16,27,28,30,33,34).…”

“…Phthalate isomers and their esters are used widely in various industries and are considered potent pollutants because of their carcinogenic, mutagenic, teratogenic, and endocrine-disrupting properties (31,32). Due to the persistence of these compounds in the environment, microorganisms have evolved and adapted to utilize them as sole sources of carbon and energy.…”