title: Gene transcription from the linear plasmid pBClin15 leads to cell lysis and extracellular DNA-dependent aggregation of Bacillus cereus ATCC 14579 in response to quinolone-induced stress.
abstract: The Bacillus cereus type strain ATCC 14579 harbours pBClin15, a linear plasmid with similar genome organization to tectiviruses. Since phage morphogenesis is not known to occur it has been suggested that pBClin15 may be a defect relic of a tectiviral prophage without relevance for the bacterial physiology. However, in this paper, we demonstrate that a pBClin15-cured strain is more tolerant to antibiotics interfering with DNA integrity than the WT strain. Growth in the presence of crystal violet or the quinolones nalidixic acid, norfloxacin or ciprofloxacin resulted in aggregation and lysis of the WT strain, whereas the pBClin15-cured strain was unaffected. Microarray analysis comparing the gene expression in the WT and pBClin15-cured strains showed that pBClin15 gene expression was strongly upregulated in response to norfloxacin stress, and coincided with lysis and aggregation of the WT strain. The aggregating bacteria experienced a significant survival benefit compared with the planktonic counterparts in the presence of norfloxacin. There was no difference between the WT and pBClin15-cured strains during growth in the absence of norfloxacin, the pBClin15 genes were moderately expressed, and no effect was observed on chromosomal gene expression. These data demonstrate for the first time that although pBClin15 may be a remnant of a temperate phage, it negatively affects the DNA stress tolerance of B. cereus ATCC 14579. Furthermore, our results warrant a recommendation to always verify the presence of pBClin15 following genetic manipulation of B. cereus ATCC 14579.
authors.affiliation: Laboratory for Microbial Dynamics (LaMDa), Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway.
authors.forename: Aniko
authors.initials: A
authors.lastname: Vörös
authors.affiliation: Laboratory for Microbial Dynamics (LaMDa), Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway.|Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Norway.|Department of Biochemistry, Institute for Cancer Research, Norwegian Radium Hospital, Oslo, Norway.
authors.forename: Roger
authors.initials: R
authors.lastname: Simm
authors.affiliation: Laboratory for Microbial Dynamics (LaMDa), Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway.
authors.forename: Jasmin K
authors.initials: JK
authors.lastname: Kroeger
authors.affiliation: Laboratory for Microbial Dynamics (LaMDa), Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway.
authors.forename: Anne-Brit
authors.initials: AB
authors.lastname: Kolstø
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism; D001409:Bacillus cereus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D001433:Bacteriolysis; D002448:Cell Adhesion; D004269:DNA, Bacterial / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D046228:Microarray Analysis; D010957:Plasmids; D015363:Quinolones / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D015363:Quinolones