Home About us MoEF Contact us Sitemap Tamil Website  
About Envis
Whats New
Research on Microbes
Microbiology Experts
Online Submission
Access Statistics

Site Visitors

blog tracking

Vol. 75, No. 20, 2009; Pages: 6478–6487

Diversity, Abundance, and Consistency of Microbial Oxygenase Expression and Biodegradation in a Shallow Contaminated Aquifer

Jane M. Yagi and Eugene L. Madsen*

Department of Microbiology, Cornell University, B57A Wing Hall, Ithaca, NY 14853.


The diversity of Rieske dioxygenase genes and short-term temporal variability in the abundance of two selected dioxygenase gene sequences were examined in a naphthalene-rich, coal tar waste-contaminated subsurface study site. Using a previously published PCR-based approach (S. M. Ní Chadhain, R. S. Norman, K. V. Pesce, J. J. Kukor, and G. J. Zylstra, Appl. Environ. Microbiol. 72:4078–4087, 2006) a broad suite of genes was detected, ranging from dioxygenase sequences associated with Rhodococcus and Sphingomonas to 32 previously uncharacterized Rieske gene sequence clone groups. The nag genes appeared frequently (20% of the total) in two groundwater monitoring wells characterized by low (~102 ppb; ~1 M) ambient concentrations of naphthalene. A quantitative competitive PCR assay was used to show that abundances of nag genes (and archetypal nah genes) fluctuated substantially over a 9-month period. To contrast short-term variation with long-term community stability, in situ community gene expression (dioxygenase mRNA) and biodegradation potential (community metabolism of naphthalene in microcosms) were compared to measurements from 6 years earlier. cDNA sequences amplified from total RNA extracts revealed that nah- and nag-type genes were expressed in situ, corresponding well with structural gene abundances. Despite evidence for short-term (9-month) shifts in dioxygenase gene copy number, agreement in field gene expression (dioxygenase mRNA) and biodegradation potential was observed in comparisons to equivalent assays performed 6 years earlier. Thus, stability in community biodegradation characteristics at the hemidecadal time frame has been documented for these subsurface microbial communities.

Keywords:Pseudomonas spp., nah genes, Burkholderia spp., phn genes,Ralstonia,Comamonas spp,physiology.

Corresponding author: Tel (607) 255-2417, Fax (607) 255-3904.

E-mail: elm3@cornell.edu


Copyright © 2005 ENVIS Centre ! All rights reserved
This site is optimized for 1024 x 768 screen resolution