Abstract:
APROACHES
TO DEFINE THE PHYSIOLOGICAL STATE OF BACTERIA
Kirchen, S*; Brändle, M; Rieder, A; Kühl, B; Marten, S; Schwartz, T; Obst, U
Karlsruhe Institute of Technology, Institute fo Functional Interfaces,
Department of Interface Microbiology, Karlsruhe, Germany
Upon
environmental stress bacteria can enter different physiological stages
including dormant states. In case of dormancies cultivation methods
underestimate the amount of viable bacteria. Thus, new detection methods are
needed to define the physiological state of bacteria. Therefore a number of
different parameters were selected to study gene expression, membrane integrity
and the cellular molecular pattern of stressed bacteria.
Using hygienically relevant bacteria the gene expression of the universal
stress protein usp and other stress responsive targets were determined.
The sigma factor rpoS, pbp5 involved in peptidoglycan synthesis
and rcsA, a regulator in biofilm synthesis in Pseudomonas aeruginosa,
enterococci and Escherichia coli respectively were investigated. Gene
induction and repression of the above mentioned genes became obvious during
stress application.
PCR based population analysis in combination with propidium monoazide (PMA)
treatment was applied to determine the efficiency of innovative disinfection
measures and to distinguish between killed, injured or living cells. Depending
on the applied treatment, the investigated natural populations using PCR and
subsequent denaturing gradient gel electrophoresis (DGGE) represented the
living part of the communities exhibiting intact membrane integrities. Mass
profiling with whole cell approaches using matrix-assisted laser
desorption/ionization (MALDI) mass spectrometry and cluster analyses applied on
enterococci resulted in distinct grouping of bacteria exhibiting different
physiological behaviors.
The presented methods form a powerful analytical platform for the
characterization of the physiological states of bacteria applicable to both
pure cultures and natural mixed populations.
Abstract
Category
31 Methodological Developments