title: Physiological and cell morphology adaptation of Bacillus subtilis at near-zero specific growth rates: a transcriptome analysis.
abstract: Nutrient scarcity is a common condition in nature, but the resulting extremely low growth rates (below 0.025 h(-1) ) are an unexplored research area in Bacillus subtilis. To understand microbial life in natural environments, studying the adaptation of B. subtilis to near-zero growth conditions is relevant. To this end, a chemostat modified for culturing an asporogenous B. subtilis sigF mutant strain at extremely low growth rates (also named a retentostat) was set up, and biomass accumulation, culture viability, metabolite production and cell morphology were analysed. During retentostat culturing, the specific growth rate decreased to a minimum of 0.00006 h(-1) , corresponding to a doubling time of 470 days. The energy distribution between growth and maintenance-related processes showed that a state of near-zero growth was reached. Remarkably, a filamentous cell morphology emerged, suggesting that cell separation is impaired under near-zero growth conditions. To evaluate the corresponding molecular adaptations to extremely low specific growth, transcriptome changes were analysed. These revealed that cellular responses to near-zero growth conditions share several similarities with those of cells during the stationary phase of batch growth. However, fundamental differences between these two non-growing states are apparent by their high viability and absence of stationary phase mutagenesis under near-zero growth conditions.
authors.affiliation: Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands; Kluyver Centre for Genomics of Industrial Fermentation, P.O. Box 5057, 2600 GA, Delft, The Netherlands.
authors.forename: Wout
authors.initials: W
authors.lastname: Overkamp
authors.forename: Onur
authors.initials: O
authors.lastname: Ercan
authors.forename: Martijn
authors.initials: M
authors.lastname: Herber
authors.forename: Antonius J A
authors.initials: AJ
authors.lastname: van Maris
authors.forename: Michiel
authors.initials: M
authors.lastname: Kleerebezem
authors.forename: Oscar P
authors.initials: OP
authors.lastname: Kuipers
mesh_terms: D000064:Acclimatization / Q000235:genetics / Q000502:physiology*; D001412:Bacillus subtilis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D018533:Biomass; D020869:Gene Expression Profiling; D005947:Glucose / Q000378:metabolism; D014158:Transcription, Genetic; D059467:Transcriptome / Q000235:genetics*
chemical_list: D005947:Glucose