SOS gene induction and possible mutagenic effects of freeze-drying in Escherichia coli and Salmonella typhimurium

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• 作者：Rachel Rosen ; Sebastian Buchinger ; Ramona Pfänder…
• 关键词：Freeze ; drying ; SOS regulon ; DNA damage ; Mutagenesis ; Lyophilization ; Bioreporters
• 刊名：Applied Microbiology and Biotechnology
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：100
• 期：21
• 页码：9255-9264
• 全文大小：552 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Biotechnology
  Microbiology
  Microbial Genetics and Genomics
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1432-0614
• 卷排序：100

文摘

We report the results of a study of the potential negative effects of the freeze-drying process, normally considered a benign means for long-term conservation of living cells and the golden standard in bacterial preservation. By monitoring gene induction using a whole-cell Escherichia coli bioreporter panel, in which diverse stress-responsive gene promoters are fused to luminescent or fluorescent reporting systems, we have demonstrated that DNA repair genes belonging to the SOS operon (recA, sulA, uvrA, umuD, and lexA) were induced upon resuscitation from the freeze-dried state, whereas other stress-responsive promoters such as grpE, katG, phoA, soxS, and sodA were not affected. This observation was confirmed by the UMU-chromotest (activation of the umuD gene promoter) in Salmonella typhimurium, as well as by real-time PCR analyses of selected E. coli SOS genes. We further show that a functional SOS operon is important in viability maintenance following resuscitation, but that at the same time, this repair system may introduce significantly higher mutation rates, comparable to those induced by high concentrations of a known mutagen. Our results also indicate that the entire freeze-drying process, rather than either freezing or drying separately, is instrumental in the induction of DNA damage.