Vijayalakshmi Gunasekaran - Academia.edu (original) (raw)

Papers by Vijayalakshmi Gunasekaran

Research paper thumbnail of Comparative Proteomic Analysis of an Ethyl Tert-Butyl Ether-Degrading Bacterial Consortium

Microorganisms

A bacterial consortium capable of degrading ethyl tert-butyl ether (ETBE) as a sole carbon source... more A bacterial consortium capable of degrading ethyl tert-butyl ether (ETBE) as a sole carbon source was enriched and isolated from gasoline-contaminated water. Arthrobacter sp., Herbaspirillum sp., Pseudacidovorax sp., Pseudomonas sp., and Xanthomonas sp. were identified as the initial populations with the 16S rDNA analysis. The consortium aerobically degraded 49% of 50 mg/L of ETBE, in 6 days. The ETBE degrading efficiency of the consortium increased to 98% even with the higher concentrations of ETBE (1000 mg/L) in the subsequent subcultures, which accumulated tert-butyl alcohol (TBA). Xanthomonas sp. and Pseudomonas sp. were identified as the predominant ETBE degrading populations in the final subculture. The metaproteome of the ETBE-grown bacterial consortium was compared with the glucose-grown bacterial consortium, using 2D-DIGE. Proteins related to the ETBE metabolism, stress response, carbon metabolism and chaperones were found to be abundant in the presence of ETBE while protei...

Research paper thumbnail of Bacterial degradation of ethyl tert-butyl ether and study of the molecular mechanisms underlying its biodegradation

L’etil tert-butil eter (ETBE) es un compost oxigenant de combustibles utilitzat a Europa per tal ... more L’etil tert-butil eter (ETBE) es un compost oxigenant de combustibles utilitzat a Europa per tal de reduir la contaminacio de l’aire produida per la combustio dels carburants d’automobils. L’us continuat d’ETBE pot contaminar les aigues degut a la seva elevada solubilitat en aigua i tambe podria ser un potencial agent carcinogenic. L’objectiu d’aquest treball es la identificacio i l’estudi de microorganismes biodegradadors potencials d’ETBE i l’analisi dels mecanismes moleculars de la biodegradacio. Dues mostres d’aigua contaminades amb gasolina s’han enriquit amb ETBE i s’han aillat dos consorcis anomenats A i B. El consorci A, format per Methylovorus sp. i Xanthomonas sp., degrada l’ETBE i BTX simultaniament i cometabolicament amb metanol, mentre que el consorci B va ser capac de creixer amb nomes ETBE i el va degradar. El consorci B degrada ETBE quasi completament i fins i tot a elevades concentracions del compost, constituint aixi un consorci amb major capacitat degradadora de l...

Research paper thumbnail of Biodegradation of fuel oxygenates and their effect on the expression of a newly identified cytochrome P450 gene in Achromobacter xylosoxidans MCM2/2/1

Process Biochemistry, 2014

Achromobacter xylosoxidans MCM2/2/1 was enriched and isolated from gasoline-contaminated soil and... more Achromobacter xylosoxidans MCM2/2/1 was enriched and isolated from gasoline-contaminated soil and was found to degrade ethyl tert-butyl ether (ETBE) and methyl tert-butyl ether (MTBE) by 41.48% and 34.15%, respectively, in 6 days. Furthermore, the effect of MTBE and TBA on the expression of cytochrome P450 (CYP) of A. xylosoxidans MCM2/2/1 was examined. The presence of the CYP gene in this organism was first confirmed by amplification of a putative 350 bp CYP gene fragment followed by identification of the entire gene by genome walking and DNA-sequencing. The identified CYP gene of A. xylosoxidans MCM2/2/1 shares a high similarity of about 88% with the thcB gene of A. xylosoxidans A8. Gene expression studies have shown that the CYP gene is expressed in A. xylosoxidans MCM2/2/1; however, the expression of this gene was altered at different concentrations of MTBE.

Research paper thumbnail of The effect of BTX compounds on the biodegradation of ETBE by an ETBE degrading bacterial consortium

Biotechnology and Bioprocess Engineering, 2013

Ethyl tert-butyl ether (ETBE) is a fuel oxygenate that is commonly used in Europe to achieve comp... more Ethyl tert-butyl ether (ETBE) is a fuel oxygenate that is commonly used in Europe to achieve complete combustion of automobile fuels and to control air pollution. It is potentially toxic and can enter the human system via contaminated water bodies. In the present study, we have identified an enriched bacterial consortium from a gasolinecontaminated site that can degrade ETBE. Bacterial consortium A was able to degrade 47% of the added ETBE in 4 days and it continued to degrade up to 51% in 9 days. Consortium A consisted of Xanthomonas sp., Methylibium sp., Methylobacillus sp., and Methylovorus sp. which were identified as the participating bacteria during ETBE degradation by DGGE-16S rDNA analysis. In addition to ETBE, this consortium degraded benzene, toluene and xylene isomers (BTX) when they were present as the sole carbon source. The degradation efficiency increased predominantly when ETBE was included as an additional carbon source. Interestingly, the degradation of ETBE decreased to 14% in 9 days when present with BTX compounds. We report that ETBE degradation is slowed down or inhibited when BTX compounds are present. This is a crucial observation for ETBE degradation in the natural environment.

Research paper thumbnail of Comparative Proteomic Analysis of an Ethyl Tert-Butyl Ether-Degrading Bacterial Consortium

Microorganisms

A bacterial consortium capable of degrading ethyl tert-butyl ether (ETBE) as a sole carbon source... more A bacterial consortium capable of degrading ethyl tert-butyl ether (ETBE) as a sole carbon source was enriched and isolated from gasoline-contaminated water. Arthrobacter sp., Herbaspirillum sp., Pseudacidovorax sp., Pseudomonas sp., and Xanthomonas sp. were identified as the initial populations with the 16S rDNA analysis. The consortium aerobically degraded 49% of 50 mg/L of ETBE, in 6 days. The ETBE degrading efficiency of the consortium increased to 98% even with the higher concentrations of ETBE (1000 mg/L) in the subsequent subcultures, which accumulated tert-butyl alcohol (TBA). Xanthomonas sp. and Pseudomonas sp. were identified as the predominant ETBE degrading populations in the final subculture. The metaproteome of the ETBE-grown bacterial consortium was compared with the glucose-grown bacterial consortium, using 2D-DIGE. Proteins related to the ETBE metabolism, stress response, carbon metabolism and chaperones were found to be abundant in the presence of ETBE while protei...

Research paper thumbnail of Bacterial degradation of ethyl tert-butyl ether and study of the molecular mechanisms underlying its biodegradation

L’etil tert-butil eter (ETBE) es un compost oxigenant de combustibles utilitzat a Europa per tal ... more L’etil tert-butil eter (ETBE) es un compost oxigenant de combustibles utilitzat a Europa per tal de reduir la contaminacio de l’aire produida per la combustio dels carburants d’automobils. L’us continuat d’ETBE pot contaminar les aigues degut a la seva elevada solubilitat en aigua i tambe podria ser un potencial agent carcinogenic. L’objectiu d’aquest treball es la identificacio i l’estudi de microorganismes biodegradadors potencials d’ETBE i l’analisi dels mecanismes moleculars de la biodegradacio. Dues mostres d’aigua contaminades amb gasolina s’han enriquit amb ETBE i s’han aillat dos consorcis anomenats A i B. El consorci A, format per Methylovorus sp. i Xanthomonas sp., degrada l’ETBE i BTX simultaniament i cometabolicament amb metanol, mentre que el consorci B va ser capac de creixer amb nomes ETBE i el va degradar. El consorci B degrada ETBE quasi completament i fins i tot a elevades concentracions del compost, constituint aixi un consorci amb major capacitat degradadora de l...

Research paper thumbnail of Biodegradation of fuel oxygenates and their effect on the expression of a newly identified cytochrome P450 gene in Achromobacter xylosoxidans MCM2/2/1

Process Biochemistry, 2014

Achromobacter xylosoxidans MCM2/2/1 was enriched and isolated from gasoline-contaminated soil and... more Achromobacter xylosoxidans MCM2/2/1 was enriched and isolated from gasoline-contaminated soil and was found to degrade ethyl tert-butyl ether (ETBE) and methyl tert-butyl ether (MTBE) by 41.48% and 34.15%, respectively, in 6 days. Furthermore, the effect of MTBE and TBA on the expression of cytochrome P450 (CYP) of A. xylosoxidans MCM2/2/1 was examined. The presence of the CYP gene in this organism was first confirmed by amplification of a putative 350 bp CYP gene fragment followed by identification of the entire gene by genome walking and DNA-sequencing. The identified CYP gene of A. xylosoxidans MCM2/2/1 shares a high similarity of about 88% with the thcB gene of A. xylosoxidans A8. Gene expression studies have shown that the CYP gene is expressed in A. xylosoxidans MCM2/2/1; however, the expression of this gene was altered at different concentrations of MTBE.

Research paper thumbnail of The effect of BTX compounds on the biodegradation of ETBE by an ETBE degrading bacterial consortium

Biotechnology and Bioprocess Engineering, 2013

Ethyl tert-butyl ether (ETBE) is a fuel oxygenate that is commonly used in Europe to achieve comp... more Ethyl tert-butyl ether (ETBE) is a fuel oxygenate that is commonly used in Europe to achieve complete combustion of automobile fuels and to control air pollution. It is potentially toxic and can enter the human system via contaminated water bodies. In the present study, we have identified an enriched bacterial consortium from a gasolinecontaminated site that can degrade ETBE. Bacterial consortium A was able to degrade 47% of the added ETBE in 4 days and it continued to degrade up to 51% in 9 days. Consortium A consisted of Xanthomonas sp., Methylibium sp., Methylobacillus sp., and Methylovorus sp. which were identified as the participating bacteria during ETBE degradation by DGGE-16S rDNA analysis. In addition to ETBE, this consortium degraded benzene, toluene and xylene isomers (BTX) when they were present as the sole carbon source. The degradation efficiency increased predominantly when ETBE was included as an additional carbon source. Interestingly, the degradation of ETBE decreased to 14% in 9 days when present with BTX compounds. We report that ETBE degradation is slowed down or inhibited when BTX compounds are present. This is a crucial observation for ETBE degradation in the natural environment.