Poster Presentations

Session Title: Novel Technologies and Methods: Functional Community Analysis
Presentation Date: Thursday, August 21, 2008
Poster Board Number: 0248

EFFECTS OF LONG-TERM STEADY STATE CONDITIONS ON RESPIRATORY FLEXIBILITY OF PARACOCCUS DENITRIFICANS

A.P. Natale, K.J. Purdy
University of Warwick, Department of Biological Sciences, Coventry, United Kingdom

Metabolic flexibility of microbial populations is commonly considered an evolutionary effect of growth in fluctuating environmental conditions. Although generally accepted, there is little experimental evidence to support this hypothesis. The aim of this study is to investigate the genetic and phenotypic effects of long-term homogeneous conditions on the respiratory flexibility of Paracoccus denitrificans, a bacterium commonly found in environments in which the oxygen availability varies dramatically. This bacterium's ability to shift from aerobic respiration to denitrification under microareophilic and anaerobic conditions makes it a popular model for respiratory metabolic studies. In this study, the use of Capillary Electrophoresis Single-Strand Conformation Polymorphism (CE-SSCP) as a suitable tool to detect the accumulation of point mutations in ssDNA fragments was validated. Sensitivity, detection limit, and manual labour time of similar techniques such as Denaturing Gradient Gel Electrophoresis (DGGE) and SSCP were compared with CE-SSCP. This technique was then used to investigate the genetic basis of adaptation in the respiratory pathways of Paracoccus denitrificans under homogeneous aerobic and anaerobic conditions. Two aerobic respiration cytochrome oxidases (aa3 and cbb3) and three denitrification reductases (Nap, Nir and Nos) were targeted in continuous cultures to investigate whether the selective pressure of long-term steady states affects the respiratory flexibility of Paracoccus denitrificans.