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Nutrients can enhance the abundance and expression of alkane hydroxylase CYP153 gene in the rhizosphere of ryegrass planted in hydrocarbon-polluted soil.

Arslan M, Afzal M, Amin I, Iqbal S, Khan QM - PLoS ONE (2014)

Bottom Line: Results obtained from these experiments showed that the bacterial inoculation improved plant growth and hydrocarbon degradation and these were further enhanced by nutrients application.The abundance and expression of CYP153 gene in the rhizosphere of ryegrass was found to be directly associated with the level of applied nutrients.It is thus concluded that the combination between vegetation, inoculation with pollutant-degrading bacteria and nutrients amendment was an efficient approach to reduce hydrocarbon contamination.

View Article: PubMed Central - PubMed

Affiliation: Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan; Earth Sciences Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia.

ABSTRACT
Plant-bacteria partnership is a promising strategy for the remediation of soil and water polluted with hydrocarbons. However, the limitation of major nutrients (N, P and K) in soil affects the survival and metabolic activity of plant associated bacteria. The objective of this study was to explore the effects of nutrients on survival and metabolic activity of an alkane degrading rhizo-bacterium. Annual ryegrass (Lolium multiflorum) was grown in diesel-contaminated soil and inoculated with an alkane degrading bacterium, Pantoea sp. strain BTRH79, in greenhouse experiments. Two levels of nutrients were applied and plant growth, hydrocarbon removal, and gene abundance and expression were determined after 100 days of sowing of ryegrass. Results obtained from these experiments showed that the bacterial inoculation improved plant growth and hydrocarbon degradation and these were further enhanced by nutrients application. Maximum plant biomass production and hydrocarbon mineralization was observed by the combined use of inoculum and higher level of nutrients. The presence of nutrients in soil enhanced the colonization and metabolic activity of the inoculated bacterium in the rhizosphere. The abundance and expression of CYP153 gene in the rhizosphere of ryegrass was found to be directly associated with the level of applied nutrients. Enhanced hydrocarbon degradation was associated with the population of the inoculum bacterium, the abundance and expression of CYP153 gene in the rhizosphere of ryegrass. It is thus concluded that the combination between vegetation, inoculation with pollutant-degrading bacteria and nutrients amendment was an efficient approach to reduce hydrocarbon contamination.

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Ratio of gene expression and gene abundance in the vegetated and unvegetated soil.
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pone-0111208-g003: Ratio of gene expression and gene abundance in the vegetated and unvegetated soil.

Mentions: The higher levels of bacterial colonization, the abundance and expression of CYP153 gene were observed in the rhizospheric soil of ryegrass vegetated in diesel-contaminated soil. A strong positive correlation (r = 0.991) between gene abundance and expression further indicated that the inoculated bacterium not only colonized but was also metabolically active in hydrocarbon degradation. In contaminated soil without vegetation, the survival of Pantoea sp. strain BTRH79 and expression of CYP153 were significantly lower than in the vegetated soil. This might be due to the fact that the inoculated rhizobacterium could not proliferate and was not metabolically active in the soil without vegetation. Nutrients application enhanced bacterial survival, the abundance and expression of CYP153 gene in the rhizosphere. Similarly, in a previous study, the addition of N, P and K in a petroleum-contaminated soil enhanced microbial population and hydrocarbon mineralization [35]. Between two levels of applied nutrients, significantly more gene abundance and expression were seen in the rhizosphere of ryegrass grown in the soil treated with higher level of nutrients. Higher amount of applied nutrients was required for bacterial proliferation and their catabolic activity [36]. The ratio between gene expression and gene abundance suggests that there were more metabolically active cells in the presence of high concentration of nutrients in the soil (Fig. 3).


Nutrients can enhance the abundance and expression of alkane hydroxylase CYP153 gene in the rhizosphere of ryegrass planted in hydrocarbon-polluted soil.

Arslan M, Afzal M, Amin I, Iqbal S, Khan QM - PLoS ONE (2014)

Ratio of gene expression and gene abundance in the vegetated and unvegetated soil.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215983&req=5

pone-0111208-g003: Ratio of gene expression and gene abundance in the vegetated and unvegetated soil.
Mentions: The higher levels of bacterial colonization, the abundance and expression of CYP153 gene were observed in the rhizospheric soil of ryegrass vegetated in diesel-contaminated soil. A strong positive correlation (r = 0.991) between gene abundance and expression further indicated that the inoculated bacterium not only colonized but was also metabolically active in hydrocarbon degradation. In contaminated soil without vegetation, the survival of Pantoea sp. strain BTRH79 and expression of CYP153 were significantly lower than in the vegetated soil. This might be due to the fact that the inoculated rhizobacterium could not proliferate and was not metabolically active in the soil without vegetation. Nutrients application enhanced bacterial survival, the abundance and expression of CYP153 gene in the rhizosphere. Similarly, in a previous study, the addition of N, P and K in a petroleum-contaminated soil enhanced microbial population and hydrocarbon mineralization [35]. Between two levels of applied nutrients, significantly more gene abundance and expression were seen in the rhizosphere of ryegrass grown in the soil treated with higher level of nutrients. Higher amount of applied nutrients was required for bacterial proliferation and their catabolic activity [36]. The ratio between gene expression and gene abundance suggests that there were more metabolically active cells in the presence of high concentration of nutrients in the soil (Fig. 3).

Bottom Line: Results obtained from these experiments showed that the bacterial inoculation improved plant growth and hydrocarbon degradation and these were further enhanced by nutrients application.The abundance and expression of CYP153 gene in the rhizosphere of ryegrass was found to be directly associated with the level of applied nutrients.It is thus concluded that the combination between vegetation, inoculation with pollutant-degrading bacteria and nutrients amendment was an efficient approach to reduce hydrocarbon contamination.

View Article: PubMed Central - PubMed

Affiliation: Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan; Earth Sciences Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia.

ABSTRACT
Plant-bacteria partnership is a promising strategy for the remediation of soil and water polluted with hydrocarbons. However, the limitation of major nutrients (N, P and K) in soil affects the survival and metabolic activity of plant associated bacteria. The objective of this study was to explore the effects of nutrients on survival and metabolic activity of an alkane degrading rhizo-bacterium. Annual ryegrass (Lolium multiflorum) was grown in diesel-contaminated soil and inoculated with an alkane degrading bacterium, Pantoea sp. strain BTRH79, in greenhouse experiments. Two levels of nutrients were applied and plant growth, hydrocarbon removal, and gene abundance and expression were determined after 100 days of sowing of ryegrass. Results obtained from these experiments showed that the bacterial inoculation improved plant growth and hydrocarbon degradation and these were further enhanced by nutrients application. Maximum plant biomass production and hydrocarbon mineralization was observed by the combined use of inoculum and higher level of nutrients. The presence of nutrients in soil enhanced the colonization and metabolic activity of the inoculated bacterium in the rhizosphere. The abundance and expression of CYP153 gene in the rhizosphere of ryegrass was found to be directly associated with the level of applied nutrients. Enhanced hydrocarbon degradation was associated with the population of the inoculum bacterium, the abundance and expression of CYP153 gene in the rhizosphere of ryegrass. It is thus concluded that the combination between vegetation, inoculation with pollutant-degrading bacteria and nutrients amendment was an efficient approach to reduce hydrocarbon contamination.

Show MeSH
Related in: MedlinePlus