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Transcriptional activity around bacterial cell death reveals molecular biomarkers for cell viability

Author: Kort, R. · Keijser, B.J. · Caspers, M.P.M. · Schuren, F.H. · Montijn, R.
Type:article
Date:2008
Institution: TNO Kwaliteit van Leven
Source:BMC Genomics, 9
Identifier: 241277
doi: doi:10.1186/1471-2164-9-590
Article number: No.: 590
Keywords: Biology · Biotechnology · Bacterial RNA · Ribosome RNA · Biological marker · Article · Bacillus subtilis · Bacterial cell · Bacterial growth · Bacterial membrane · Bacterial reproduction · Cell culture · Cell death · Cell viability · Cellular stress response · Controlled study · Cytology · Gene cluster · Gene expression · Genetic transcription · Growth curve · Heat stress · Nonhuman · Protein folding · RNA stability · Sporogenesis · Transcription regulation · Bacterial count · DNA microarray · Gene expression profiling · Gene expression regulation · Genetics · Growth, development and aging · Heat · Heat shock response · Microbial viability · Multigene family · Physiology · Transcription initiation · Bacillus subtilis · Bacteria (microorganisms) · Posibacteria · Bacillus subtilis · Biological Markers · 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

Abstract

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. © 2008 Kort et al; licensee BioMed Central Ltd. Chemicals / CAS: Biological Markers; RNA, Bacterial