Properties of Bacillus anthracis spores prepared under various environmental conditions

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Properties of Bacillus anthracis spores prepared under various environmental conditions Renu B. Baweja · Mohd S. Zaman · Abid R. Mattoo · Kirti Sharma · Vishwas Tripathi · Anita Aggarwal · Gyanendra P. Dubey · Raj K. Kurupati · Munia Ganguli · N. K. Chaudhury · Somdutta Sen · Taposh K. Das · Wasudev N. Gade · Yogendra Singh

Received: 2 December 2006 / Revised: 28 July 2007 / Accepted: 4 August 2007 / Published online: 23 August 2007 © Springer-Verlag 2007

Abstract Bacillus anthracis makes highly stable, heatresistant spores which remain viable for decades. EVect of various stress conditions on sporulation in B. anthracis was studied in nutrient-deprived and sporulation medium adjusted to various pH and temperatures. The results revealed that sporulation eYciency was dependent on conditions prevailing during sporulation. Sporulation occurred earlier in culture sporulating at alkaline pH or in PBS than control. Spores formed in PBS were highly sensitive towards spore denaturants whereas, those formed at 45°C were highly resistant. The decimal reduction time (D-10 time) of the spores formed at 45°C by wet heat, 2 M HCl, 2 M NaOH and 2 M H2O2 was higher than the respective

Communicated by Erko Stackebrandt. R. B. Baweja · M. S. Zaman · A. R. Mattoo · K. Sharma · V. Tripathi · A. Aggarwal · G. P. Dubey · R. K. Kurupati · M. Ganguli · Y. Singh (&) Institute of Genomics and Integrative Biology, Mall Road, Delhi, 110007, India e-mail: [email protected] N. K. Chaudhury Institute of Nuclear Medicine and Allied Sciences, Delhi, India S. Sen The Centre for Genomic Application, 254 Okhla Industrial Area, New Delhi, India T. K. Das All India Institute of Medical Sciences, New Delhi, India W. N. Gade Department of Biotechnology, Pune University, Pune, India

D-10 time for the spores formed in PBS. The dipicolinic acid (DPA) content and germination eYciency was highest in spores formed at 45°C. Since DPA is related to spore sensitivity towards heat and chemicals, the increased DPA content of spores prepared at 45°C may be responsible for increased resistance to wet heat and other denaturants. The size of spores formed at 45°C was smallest amongst all. The study reveals that temperature, pH and nutrient availability during sporulation aVect properties of B. anthracis spores. Keywords Bacillus anthracis · Spore sensitivity · Sporulation · Germination · Dipicolinic acid

Introduction In the natural environment, bacteria acclimatize to a variety of adverse conditions, such as Xuctuating temperatures, pH and nutrient limitation. Members of the genus Bacillus respond to such hostile conditions by adopting an alternative developmental pathway leading to sporulation. Bacillus anthracis, a mammalian pathogen, is the etiological agent of anthrax. The infection occurs from intradermal inoculation, ingestion or inhalation of the spores (Klein et al. 1966). Bioterrorist attacks with B. anthracis spores have sparked renewed interest in studying methods of bacterial spore inactivation. In earlier studies, electron beam irradiat