BACKGROUND: In bacteriology, the ability to grow in selective media and to form colonies on nutrient agar plates is routinely used as a retrospective criterion for the detection of living bacteria. However, the utilization of indicators for bacterial viability-such as the presence of specific transcripts or membrane integrity-would overcome bias introduced by cultivation and reduces the time span of analysis from initiation to read out. Therefore, we investigated the correlation between transcriptional activity, membrane integrity and cultivation-based viability in the Gram-positive model bacterium Bacillus subtilis.
RESULTS: We present microbiological, cytological and molecular analyses of the physiological response to lethal heat stress under accurately defined conditions through systematic sampling of bacteria from a single culture exposed to gradually increasing temperatures. We identified a coherent transcriptional program including known heat shock responses as well as the rapid expression of a small number of sporulation and competence genes, the latter only known to be active in the stationary growth phase.
CONCLUSION: The observed coordinated gene expression continued even after cell death, in other words after all bacteria permanently lost their ability to reproduce. Transcription of a very limited number of genes correlated with cell viability under the applied killing regime. The transcripts of the expressed genes in living bacteria -- but silent in dead bacteria-include those of essential genes encoding chaperones of the protein folding machinery and can serve as molecular biomarkers for bacterial cell viability.
|Publication status||Published - 6 Dec 2008|
- Bacillus subtilis
- Colony Count, Microbial
- Gene Expression Profiling
- Gene Expression Regulation, Bacterial
- Heat-Shock Response
- Hot Temperature
- Microbial Viability
- Multigene Family
- Oligonucleotide Array Sequence Analysis
- RNA Stability
- RNA, Bacterial
- Transcription, Genetic
- Transcriptional Activation
- Journal Article