GENOMICS AND PROTEOMICS Global transcriptome analysis of the Mycobacterium bovis BCG response to sodium hypochlorite Hyeung-Jin Jang & Chantal Nde & Freshteh Toghrol & William E. Bentley Received: 27 July 2009 / Revised: 12 August 2009 / Accepted: 13 August 2009 / Published online: 16 September 2009 # US Government 2009 Abstract Tuberculosis is a common and often deadly infectious disease caused by mycobacteria, mainly Myco- bacterium tuberculosis and infrequently by other subspe- cies of the M. tuberculosis complex, such as M. bovis. Sodium hypochlorite (bleach) is routinely used in hospitals and health care facilities for surface sterilization; however, the modes of action of bleach on M. bovis BCG and how this organism develops resistance to sodium hypochlorite have not been elucidated. In this study, we performed a global toxicogenomic analysis of the M. bovis response to 2.5 mM sodium hypochlorite after 10 and 20 min. M. bovis BCG growth was monitored by measuring the quantity of ATP in picomoles produced over a short exposure time (10–60 min) to sodium hypochlorite. This study revealed significant regulation of oxidative stress response genes of M. bovis BCG, such as oxidoreductase, peroxidase, heat shock proteins and lipid transport, and metabolism genes. We interpreted this response as a potentially more lethal interplay between fatty acid metabolism, sulfur metabolism, and oxidative stress. Our results also suggest that sodium hypochlorite repressed transcription of genes involved in cell wall synthesis of M. bovis. This study shows that the treatment of M. bovis BCG with bleach inhibits the biosynthesis of outer cell wall mycolic acids and also induces oxidative damage. Keywords Toxicogenomics . Microarray . Mycobacterium bovis BCG . Sodium hypochlorite . Bleach Introduction Tuberculosis (TB) is a common and often deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis and infrequently by other subspecies of the M. tuberculosis complex, such as M. bovis. The 2004 World Health Organization mortality and morbidity statistics show that 14.6 million chronic active TB cases, 8.9 million new cases, and 1.6 million deaths occurred that year, the majority of which happened in developing countries. According to a report from the Centers for Disease Control and Prevention, from 1993 to 2006, the number of TB cases in the USA decreased by 45%, from 25,107 to 13,779. This decline occurred unequally in the USA: among the US-born population, the numbers of cases fell by 66% while the number of cases among foreign-born people in the USA increased by 5% (Cain et al. 2008). Recently, the Bill and Melinda Gates foundation contributed to support the fight against global health threats from infectious diseases such as AIDS, malaria, and TB. Bill Gates has also appealed to the world’ s industrialized nations to show an increased commitment to the fight against the global threat of infectious diseases (Pasterkamp 2001). Electronic supplementary material The online version of this article (doi:10.1007/s00253-009-2208-0) contains supplementary material, which is available to authorized users. H.-J. Jang Department of Biochemistry, College of Oriental Medicine, Kyung Hee University, Seoul 130–701, Republic of Korea C. Nde : W. E. Bentley Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, MD 20742, USA F. Toghrol (*) Microarray Research Laboratory, Biological and Economic Analysis Division, Office of Pesticide Programs, US Environmental Protection Agency, Fort Meade, MD 20755, USA e-mail: toghrol.freshteh@epa.gov Appl Microbiol Biotechnol (2009) 85:127–140 DOI 10.1007/s00253-009-2208-0