African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5223

Full Length Research Paper

Isotope effects on cell growth and sporulation, and spore heat resistance, survival and spontaneous mutation of Bacillus cereus by deuterium oxide culture

Ming-Feng Lu1,2*, Yue-Jie Zhang2 and Hong-Yu Zhang3,4
1School of Life Sciences, Shandong Normal University, Jinan 250014, P. R. China. 2School of Life Sciences, Shandong University of Technology, Zibo 255091, P. R. China. 3National Key Laboratory of Crop Genetic Improvement, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China. 4Center for Bioinformatics, Huazhong Agricultural University, Wuhan 430070, P. R. China.  
Email: [email protected]

  •  Accepted: 19 June 2012
  •  Published: 19 February 2013

Abstract

Deuterated spores of Bacillus cereus were prepared using a multi-stage adaptation protocol and then preserved at -20, 4, 25 and 40°C, respectively, to investigate the genetic mutation effects of deuterium oxide (D2O) isotope. The effects of the D2O isotope on cell growth and sporulation, and spore heat resistance, survival and spontaneous mutation rate of spores were examined. The results suggested that B. cereus cells can be grown in a cultured medium containing 98% D2O, with no observed growth inhibitory effect. The improved heat resistance of the deuterated spores and the decreased sporulation rate were accompanied by an increase in the D2O concentration in the cultured medium. Although, the survival rate of spores reduced along with the extension of the preservation time, in contrast to spores cultured by H2O medium, the deuterated spores had higher survival rate at -20 and 40°C at storage, respectively. In general, the spontaneous mutation rate increased along with preservation temperature and time. The spontaneous mutation rate of the deuterated spores significantly decreased when compared with that of hydrogen culture (P<0.05). This result provided a preliminary experimental evidence to validate the Löwdin DNA mutation model based on the inter-base double proton transfer in a hydrogen pond of base pairs.

 

Key words: Deuterium oxide, Isotope effect, spontaneous mutation, proton-tunneling model.