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Metabolism of 4-chloro-2-nitrophenol in a gram-positive bacterium, Exiguobacterium sp. PMA.

Arora PK, Sharma A, Mehta R, Shenoy BD, Srivastava A, Singh VP - Microb. Cell Fact. (2012)

Bottom Line: The effects of different substrate concentrations and various inoculum sizes on degradation of 4C2NP were investigated.Exiguobacterium sp.The crude extract of 4C2NP-induced PMA cells contained enzymatic activity for 4C2NP reductase and 4C2AP dehalogenase, suggesting the involvement of these enzymes in the degradation of 4C2NP.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbial Type Culture Collection (MTCC) and Gene Bank, CSIR-Institute of Microbial Technology, Sec-39A, Chandigarh 1600036, India. arora484@gmail.com

ABSTRACT

Background: Chloronitrophenols (CNPs) are widely used in the synthesis of dyes, drugs and pesticides, and constitute a major group of environmental pollutants. 4-Chloro-2-nitrophenol (4C2NP) is an isomer of CNPs that has been detected in various industrial effluents. A number of physicochemical methods have been used for treatment of wastewater containing 4C2NP. These methods are not as effective as microbial degradation, however.

Results: A 4C2NP-degrading bacterium, Exiguobacterium sp. PMA, which uses 4C2NP as the sole carbon and energy source was isolated from a chemically-contaminated site in India. Exiguobacterium sp. PMA degraded 4C2NP with the release of stoichiometeric amounts of chloride and ammonium ions. The effects of different substrate concentrations and various inoculum sizes on degradation of 4C2NP were investigated. Exiguobacterium sp. PMA degraded 4C2NP up to a concentration of 0.6 mM. High performance liquid chromatography and gas chromatography-mass spectrometry identified 4-chloro-2-aminophenol (4C2AP) and 2-aminophenol (2AP) as possible metabolites of the 4C2NP degradation pathway. The crude extract of 4C2NP-induced PMA cells contained enzymatic activity for 4C2NP reductase and 4C2AP dehalogenase, suggesting the involvement of these enzymes in the degradation of 4C2NP. Microcosm studies using sterile and non-sterile soils spiked with 4C2NP were carried out to monitor the bioremediation potential of Exiguobacterium sp. PMA. The bioremediation of 4C2NP by Exiguobacterium sp. PMA was faster in non-sterilized soil than sterilized soil.

Conclusions: Our studies indicate that Exiguobacterium sp. PMA may be useful for the bioremediation of 4C2NP-contaminated sites. This is the first report of (i) the formation of 2AP in the 4C2NP degradation pathway by any bacterium and (iii) the bioremediation of 4C2NP by any bacterium.

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HPLC elution profile of samples of degradation of 4C2NP by Exiguobacterium sp. PMA. HPLC confirmed complete depletion of 4C2NP by Exiguobacterium sp. PMA within 44 h. Metabolite I was detected in sample of 24 and 36 h whereas metabolite 11 was detected only in the sample of 36 h.
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Figure 2: HPLC elution profile of samples of degradation of 4C2NP by Exiguobacterium sp. PMA. HPLC confirmed complete depletion of 4C2NP by Exiguobacterium sp. PMA within 44 h. Metabolite I was detected in sample of 24 and 36 h whereas metabolite 11 was detected only in the sample of 36 h.

Mentions: High Performance Liquid Chromatography (HPLC) and Gas chromatography–mass spectrometry (GC-MS) studies were carried out to elucidate metabolic pathway of 4C2NP in Exiguobacterium sp. PMA. HPLC confirmed complete depletion of 4C2NP by Exiguobacterium sp. PMA within 44 h (Figure 2). In the 12 h sample, only parent compound was detected. The metabolite I was detected in the sample of 24 h and 36 h whereas the metabolite II was detected only in the 36 h sample. In the sample of 44 h, neither parent compound nor metabolite was detected. The retention time of 4C2NP, metabolite 1 and metabolite II were 16.4 min, 10.6 min and 7.7 min, respectively. The retention times of metabolite I and II were exactly match with that of authentic 4-chloro-2-aminophenol (4C2AP) and 2-aminophenol (2AP).


Metabolism of 4-chloro-2-nitrophenol in a gram-positive bacterium, Exiguobacterium sp. PMA.

Arora PK, Sharma A, Mehta R, Shenoy BD, Srivastava A, Singh VP - Microb. Cell Fact. (2012)

HPLC elution profile of samples of degradation of 4C2NP by Exiguobacterium sp. PMA. HPLC confirmed complete depletion of 4C2NP by Exiguobacterium sp. PMA within 44 h. Metabolite I was detected in sample of 24 and 36 h whereas metabolite 11 was detected only in the sample of 36 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3539986&req=5

Figure 2: HPLC elution profile of samples of degradation of 4C2NP by Exiguobacterium sp. PMA. HPLC confirmed complete depletion of 4C2NP by Exiguobacterium sp. PMA within 44 h. Metabolite I was detected in sample of 24 and 36 h whereas metabolite 11 was detected only in the sample of 36 h.
Mentions: High Performance Liquid Chromatography (HPLC) and Gas chromatography–mass spectrometry (GC-MS) studies were carried out to elucidate metabolic pathway of 4C2NP in Exiguobacterium sp. PMA. HPLC confirmed complete depletion of 4C2NP by Exiguobacterium sp. PMA within 44 h (Figure 2). In the 12 h sample, only parent compound was detected. The metabolite I was detected in the sample of 24 h and 36 h whereas the metabolite II was detected only in the 36 h sample. In the sample of 44 h, neither parent compound nor metabolite was detected. The retention time of 4C2NP, metabolite 1 and metabolite II were 16.4 min, 10.6 min and 7.7 min, respectively. The retention times of metabolite I and II were exactly match with that of authentic 4-chloro-2-aminophenol (4C2AP) and 2-aminophenol (2AP).

Bottom Line: The effects of different substrate concentrations and various inoculum sizes on degradation of 4C2NP were investigated.Exiguobacterium sp.The crude extract of 4C2NP-induced PMA cells contained enzymatic activity for 4C2NP reductase and 4C2AP dehalogenase, suggesting the involvement of these enzymes in the degradation of 4C2NP.

View Article: PubMed Central - HTML - PubMed

Affiliation: Microbial Type Culture Collection (MTCC) and Gene Bank, CSIR-Institute of Microbial Technology, Sec-39A, Chandigarh 1600036, India. arora484@gmail.com

ABSTRACT

Background: Chloronitrophenols (CNPs) are widely used in the synthesis of dyes, drugs and pesticides, and constitute a major group of environmental pollutants. 4-Chloro-2-nitrophenol (4C2NP) is an isomer of CNPs that has been detected in various industrial effluents. A number of physicochemical methods have been used for treatment of wastewater containing 4C2NP. These methods are not as effective as microbial degradation, however.

Results: A 4C2NP-degrading bacterium, Exiguobacterium sp. PMA, which uses 4C2NP as the sole carbon and energy source was isolated from a chemically-contaminated site in India. Exiguobacterium sp. PMA degraded 4C2NP with the release of stoichiometeric amounts of chloride and ammonium ions. The effects of different substrate concentrations and various inoculum sizes on degradation of 4C2NP were investigated. Exiguobacterium sp. PMA degraded 4C2NP up to a concentration of 0.6 mM. High performance liquid chromatography and gas chromatography-mass spectrometry identified 4-chloro-2-aminophenol (4C2AP) and 2-aminophenol (2AP) as possible metabolites of the 4C2NP degradation pathway. The crude extract of 4C2NP-induced PMA cells contained enzymatic activity for 4C2NP reductase and 4C2AP dehalogenase, suggesting the involvement of these enzymes in the degradation of 4C2NP. Microcosm studies using sterile and non-sterile soils spiked with 4C2NP were carried out to monitor the bioremediation potential of Exiguobacterium sp. PMA. The bioremediation of 4C2NP by Exiguobacterium sp. PMA was faster in non-sterilized soil than sterilized soil.

Conclusions: Our studies indicate that Exiguobacterium sp. PMA may be useful for the bioremediation of 4C2NP-contaminated sites. This is the first report of (i) the formation of 2AP in the 4C2NP degradation pathway by any bacterium and (iii) the bioremediation of 4C2NP by any bacterium.

Show MeSH
Related in: MedlinePlus