title: Environmental stress speeds up DNA replication in Pseudomonas putida in chemostat cultivations.
abstract: Cellular response to different types of stress is the hallmark of the cell's strategy for survival. How organisms adjust their cell cycle dynamics to compensate for changes in environmental conditions is an important unanswered question in bacterial physiology. A cell using binary fission for reproduction passes through three stages during its cell cycle: a stage from cell birth to initiation of replication, a DNA replication phase and a period of cell division. We present a detailed analysis of durations of cell cycle phases, investigating their dynamics under environmental stress conditions. Applying continuous steady state cultivations (chemostats), the DNA content of a Pseudomonas putida KT2440 population was quantified with flow cytometry at distinct growth rates. Data-driven modeling revealed that under stress conditions, such as oxygen deprivation, solvent exposure and decreased iron availability, DNA replication was accelerated correlated to the severity of the imposed stress (up to 1.9-fold). Cells maintained constant growth rates by balancing the shortened replication phase with extended cell cycle phases before and after replication. Transcriptome data underpin the transcriptional upregulation of crucial genes of the replication machinery. Hence adaption of DNA replication speed appears to be an important strategy to withstand environmental stress.
authors: Institute for Biochemical Engineering, University of Stuttgart, Stuttgart, Germany.
authors: Sarah
authors: S
authors: Lieder
authors: Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
authors: Michael
authors: M
authors: Jahn
authors: Institute for Biochemical Engineering, University of Stuttgart, Stuttgart, Germany.
authors: Joachim
authors: J
authors: Koepff
authors: Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
authors: Susann
authors: S
authors: Müller
authors: Institute for Biochemical Engineering, University of Stuttgart, Stuttgart, Germany. takors@ibvt.uni-stuttgart.de.
authors: Ralf
authors: R
authors: Takors
mesh_terms: D061249:Batch Cell Culture Techniques / Q000379:methods; D002453:Cell Cycle; D004261:DNA Replication; D004269:DNA, Bacterial / Q000235:genetics*; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D008954:Models, Biological; D016958:Pseudomonas putida / Q000235:genetics / Q000254:growth & development*; D013312:Stress, Physiological
chemical_list: D004269:DNA, Bacterial
keywords: Chemostat; DNA replication; Environmental stress; Flow cytometry; Pseudomonas putida