SARANNA FANNING^1,2, DOUWE VAN SINDEREN¹

1. University College Cork, Department of Microbiology and
Alimentary Pharmabiotic Centre Cork, Ireland

2. Carnegie Mellon University, Department of Biological Sciences, Pittsburgh, PA 15213, USA

Abstract

The gastrointestinal microbiota is presumed to play a beneficial role in human health (1-10), and extensive efforts have been made to investigate this microbiota, and influence its composition to gain health benefits (11-18). Many members of the gut microbiota are classified as health-promoting or probiotic, imparting activities such as prevention of colonization and/or persistence of pathogens, promoting host immune responses and antimicrobial activity (19-27). In order to confer their benefits, probiotics must, at least temporarily, colonize the gut and survive environmental perturbations. Recent research suggests that a polysaccharide or sugar coating on the outside of the cell envelope is critical for in vivo cell survival (25, 28-30). This review addresses the attributes of polysaccharide coatings that may contribute to probiotic survival in the gut.

WHAT ARE PROBIOTICS AND WHY IS THEIR IN VIVO SURVIVAL IMPORTANT?

The word probiotic, meaning “for life”, makes reference to the ability of certain bacteria to restore a healthy balance within the gastrointestinal tract (GIT) when it is disturbed due to, for example, the use of antibiotics, stress, consumption of sterile foods, and ageing. The most widely adopted definition is that from the World Health Organization stating a probiotic to represent "live microorganisms which when administered in adequate amounts confer a health benefit on the host" (World Health Organization, 2001). The beneficial attributes of probiotics have been reviewed (31-33), and include immune modulation, decreased pathogen load and easing of irritable bowel syndrome, reducing blood pressure and cardiovascular disease risk factors (34). Probiotics are reported to affect systemic and mucosa-associated immune responses, to modulate macrophage function and cytokine production, while they are also understood to play a role in counteracting certain human infections, including, among others, urinary tract infections, rotavirus-mediated gastroenteritis, and Clostridium difficile-indu ...