Factors affecting the emergence of pathogens on foods.

Recent times have seen the emergence of a number of new or emerging pathogens. Research is needed to establish the mechanisms underlying their emergence in foods, and their interactions with traditional food production processes. The paper reviews the general relationships between environmental stresses and pathogen emergence. Non genetic mechanisms of pathogen adaptation to stress are considered, focusing on acid resistance as an example of particular importance to pathogen survival in food and the human host. The influence of environmental factors in genetic adaptation in stationary phase cells are considered in relation to the development of non-directed antibiotic resistance, i.e. development of resistance when antibiotics are not present in the environment. The paper examines the molecular mechanisms underlying such genetic processes and their enhancement during environmental stress. The implications of these mechanisms for food safety and pathogen emergence are discussed.