Novel applications of Lactic Acid Bacteria (LAB) and Recombinant LAB as immune-modulator, antimicrobial and therapeutic agent

Abstract

Lactic acid bacteria (LAB), present in intestines of most animals and humans, plays an important role as starters of fermented food products where it acts as a biopreservative, preventing spoilage by pathogenic microorganisms through acidification, competition for essential nutrients, and / or production of inhibitory compounds. The beneficial role played by these microorganisms in the humans and other animals, including the effect on the immune system, has been reported. LAB are gaining importance due to their “generally recognized as safe” status, long-term use in food and beneficial, probiotic properties. The activation of the systemic and secretory immune response by LAB requires many complex interactions among the different constituents of the intestinal ecosystem (microflora, epithelial cells and immune cells). Furthermore, as LAB can acquire new, desirable traits by the incorporation of genes, that allows the expression of heterologous proteins, they are being probed extensively for construction of a delivery and clearing system for the generation of food-grade recombinant lactic acid bacterium strains ,which can
also act as vaccine vehicles for mucosal administration. Highly efficient expression vectors have been developed which successfully expressed and secreted heterologous fusion proteins in Lactobacilli. Hence, derivatives of
non-pathogenic food related bacteria are currently being evaluated as live vaccines. Several strains have been evaluated for their ability to produce and secrete the B subunit of cholera toxin (CTB), alpha-amylase,
or an epitope from human immunodeficiency virus (gp41 protein) under the control of a set of expression or expression/secretion signals from various lactic acid bacteria. The review describes some of the
immunomodulatory and anti microbial activities of LAB with specific focus on the mechanisms involved in these processes.
LAB, Probiotics, Prebiotics, Synbiotics, Anti microbial,

Keywords: Immunomodulatory, Anti cancer, Recombinant LAB