Probiotics as Biotherapeutic Agents: Present Knowledge and Future Prospects

Abstract

Since the early observations of Elie Metchnikoff, a wealth of experiments have described the use of selected microorganisms, mainly belonging to the lactic acid bacteria family, for the prevention or treatment of a variety of pathological situations. Nevertheless, the mechanisms underlying the proposed actions remain vastly unknown, partly as a consequence of the complexity of the gastro-intestinal ecosystem with which these biotherapeutic agents are expected to interact, but also because of the increasing variety of strains considered to have potential probiotic characteristics. During the past decades, however, the beneficial effect of specific strains in preventing or treating intestinal disorders has been substantiated by well-controlled clinical trials. Increasing evidence, including human studies, is also supporting the immunomodulatory role attributed to given lactic acid bacterial strains. The desire by consumers to use natural methods for health maintenance rather than long-term chemotherapeutic agents (i.e. antibiotics), linked to their expectation that food becomes a source of prolonged well-being, supports the speculation that the probiotic market will expand rapidly. Much of this growth will also depend on the reliability of claims that these products will bare. Therefore, the legislator will have to provide clear rules and regulations which will depend on measurable biomarkers and criteria based on scientific evidence. These commercial and legislative needs will hopefully provide scientists with the resources necessary to conduct the multidisciplinary research required to establish facts and mechanisms of action for carefully selected probiotic strains. These research results will probably be as essential for the positioning of probiotic preparations as either a food, a food supplement or as pharmaceutical preparation.

High-level, inducible gene expression in Lactobacillus sakei and Lactobacillus plantarum using versatile expression vectors

“…Lactobacillus plantarum is also found in many habitats, including dairy and meat products, plant and vegetable fermentations, and in the gastrointestinal tract and oral cavity of humans (Axelsson & Ahrné, 2000). Some L. plantarum strains have probiotic effects on human health (Alander et al, 1999;Schultz et al, 2002;Mercenier et al, 2003). Lactobacilli have great potential as food-grade cell factories and as delivery vehicles for interesting proteins, such as antigens, antibodies and growth factors (Pouwels et al, 1996(Pouwels et al, , 2001Pavan et al, 2000;Krüger et al, 2002;Scheppler et al, 2002).…”

Construction of a combined physical and genetic map of the chromosome of Lactobacillus acidophilus ATCC 4356 and characterization of the rRNA operons

“…The evidence of these beneficial effects has led to the use of a broad range of Lactobacillus species as 'probiotic' bacteria (e.g. Gilliland, 1990;Goldin, 1998;Vaughan et al, 1999;Gorbach, 2000;Rolfe, 2000;Mercenier et al, 2003). Also, in recent years, selected Lactobacillus species have been used as vaccine delivery systems, which can be administered orally and can effectively induce protective immune responses (Mercenier et al, 1996;Wells et al, 1996;Pouwels et al, 2001;Seegers, 2002;Scheppler et al, 2002).…”

The genome sequence of the probiotic intestinal bacterium Lactobacillus johnsonii NCC 533

“…It has been proposed that a balanced and diverse microbiota is essential for healthy intestinal function, as well as resistance to infection by enteric pathogens (4). As a result, several lactobacilli, a few bifidobacteria, and their fermented food products are extensively marketed as probiotic foods (5,6).…”