Molecular approaches to study probiotic bacteria

Functional foods comprising probiotic bacteria are receiving Increasing att ention from the scientific community and science funding agencies [1]. An e ssential aspect relating to the functionality of probiotic-based foods is t o develop molecular methods to determine the presence, activity and viabili ty of probiotic bacteria in the human gastrointestinal [GI] tract [2]. The CI tract is composed of a complex ecosystem of various microbial habitats c olonized by numerous different commensal micro-organisms. This indigenous g ut microbiota is essential to the overall health of the host by performing important physiological functions. In particular, they protect against path ogenic bacteria and drive the development of the immune system during neona tal life. Further metabolic activities of the CI microbiota that beneficial ly affect the host include continued degradation of food components, vitami n production, and production of short chain fatty acids that feed the colon ic mucosa. It is clear that Factors such as diet, sickness, stress, or medi cation can result in loss of well-being of the host, and it is assumed that some of these symptoms are due to perturbation of what is termed the norma l balance of the gut microbiota. Knowledge of the structure and function of the standard microbiota. and its response to diet, genetic background and lifetime of the host must be taken into account when designing probiotic-ba sed functional foods. The application of molecular techniques for detection and identification of microbes has provided a major breakthrough in the an alysis of microbial ecosystems and their function [3]. The successful appli cation and further potential of these molecular methods to study probiotic bacteria and their impact on the standard CI microbiota is discussed below. (C) 2000 Elsevier Science Ltd. All Fights reserved.