African Journal of Microbiology Research Vol. 5(29), pp. 5188-5193, 9 December, 2011 Available online at http://www.academicjournals.org/AJMR ISSN 1996-0808 ©2011 Academic Journals DOI: 10.5897/AJMR11.929 Full Length Research Paper Expression of chitinase and chitin binding proteins (CBP’s) by Listeria monocytogenes J0161 in biofilm and Co-culture broths Prem Saran Tirumalai and Soam Prakash* Environmental and Advanced Parasitology Lab, Department of Zoology, Faculty of Science, Dayalbagh Educational Institute (Deemed University), Dayalbagh, Agra – 282110, India. Accepted 17 October, 2011 Listeria monocytogenes is a dreaded pathogen colonizes to form biofilm in the natural environments and in food processing facility. Biofilm state makes the bacterium resistant to antimicrobial agents. L. monocytogenes, an intracellular parasite also colonizes the mammalian epithelial cells in the gut. Chitinase and other chitinolytic proteins expressed by L. monocytogenes contribute to the colonization of the bacterium in the intestine. It has been reported that chitinase and chitin binding proteins are essential for attachment of the bacterium to the epithelial cells. In this study, we have pursued to analyze, if chitinase and chitin binding proteins play a role in biofilm formation and the expression of these proteins otherwise in a co-culture state. We report the expression pattern of these proteins, which supports our claim that chitinase and chitin binding proteins have a role to play in biofilm formation. Key words: Listeria monocytogenes, chitinase, microarray, biofilm, co-culture, gene expression. INTRODUCTION Listeria monocytogenes is a Gram-positive saprophyte that is found in soil, water, and decaying vegetation (Chaturongakul et al., 2008; Czuprynski, 2005; Freitag et al., 2009). If consumed by a susceptible host, L. monocytogenes can adopt a pathogenic lifestyle and lead to fatal infections (Allerberger and Wagner, 2010; Barbuddhe and Chakraborty 2009). While significant attention has focused on the gene products of L. monocytogenes that specifically contribute to sustenance within host cells, relatively less is known on the genes that contribute to bacterial life outside the infected host. The role of chitinases in the growth of L. monocytogenes in environmental conditions is well *Corresponding author. E-mail: prakashsoamdei@gmail.com. Tel: +91 9410421149. Fax: +91 562 2801226. Abbreviations: CF, Cystic fibrosis; TSB, tryptone soy broth; PBS, phosphate buffer solution; DNA, deoxyribonucleic acid. documented (Leisner et al., 2008). In fact, chitin binding proteins (CBP’s) and chitinases are hypothesized to con- tribute to adherence and sustenance of some bacterial species in the environment (Kirn et al., 2005). Chitinases are glycosyl hydrolases that catalyze the hydrolysis of the 1,4-beta-linkages in chitin. Chitinases are found in a wide range of species from all kingdom of life, which includes bacteria, viruses, higher plants as well as mammals. Chitinases have diverse physiological and biological roles depending on the organisms. They also play an important part in maintaining the chitin balance in the natural environment. In addition, to the functions of regulating cellular growth and proliferation, chitinases also play an important biological role in defending the host cells or by increasing interaction with pathogens due to their ability to hydrolyze and/or interact with chitin present in pathogens or host cells. In Vibrio cholerae, chitinase have been reported to contribute to virulence and pathogenicity. The role of bacterial CBP’s in the processes of pathogenesis (for example, adhesion, colonization) to the host cells has been reported (Kirn et