Chitin hydrolysis by Listeria spp. including L. monocytogenes

Department of Veterinary Pathobiology, Faculty of Life Sciences, University of Copenhagen, Copenhagen, Denmark

^* To whom correspondence should be addressed. Email: jjl{at}life.ku.dk.

	Abstract

Listeria spp., including the food borne pathogen Listeria monocytogenes are ubiquitous micro organisms in the environment and thus are difficult to exclude from food processing plants. The factors that contribute to their multiplication and survival in nature are not well understood but the ability to catabolize various carbohydrates is likely to be very important. One major source of carbon and nitrogen in nature is chitin, an insoluble linear -1,4-linked polymer of N-acetylglucosamine (GlcNAc). Chitin is found in cell walls of fungi and certain algae, in the cuticles of arthropods and in shells and radulae of molluscs. In the present study we demonstrate that Listeria monocytogenes and other Listeria spp. are able to hydrolyze -chitin. The chitinolytic activity is repressed by presence of glucose in the media suggesting that chitinolytic activity is subjected to catabolite repression. Activity is also regulated by temperature and is higher at 30°C compared to 37°C. In L. monocytogenes EGD chitin hydrolysis depends on genes encoding two chitinases, lmo0105 (chiB) and lmo1883 (chiA) but not on a gene, lmo2467, encoding a putative chitin binding protein. The chiB and chiA genes are phylogenetically related to various well characterized chitinases. The potential biological implications of chitinolytic activity of Listeria are discussed.