Development of molecular tools for bifidobacterium species

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Probiotic and prebiotic products as "quality of life and managing biological resources" are on the market in the forms of milk based drinks, yogurts and capsules. Intake of probiotic bacteria is associated with beneficial health benefits to the human and animal hosts, but current understanding of how the bacteria actually illicit these effects is not very good. Although the genetics and molecular tools of more common dairy lactic bacteria like Lactococcus and Lactobacillus exist, knowledge is lacking behind with closely related Bifidobacterium genus, which is phylogenetically and physiologically (bifidus shunt) distinct. After the molecular tools and mechanisms are elucidated, a more rational approach to the therapeutic use of probiotics could be possible. The current focus of my research program is centered on the hypothesis that one can study fundamental scientific knowledge and improve the performance of probiotic strain by genetic manipulation of its expression of certain proteins. As genetic tools become available for bifidobacteria, more work can be done on understanding their physiology and metabolic activities important for survival in food as well as for understanding their beneficial effects in the gastrointestinal system. The short term objectives are to (1) develop food grade cloning and expression systems, (2) construct new over-expression systems for production of a heterologous protein like bile salt hydrolase (BSH) to validate BSH hypothesis for cholesterol lowering effect of Bifidoabcterium lactis strains (BSH mutant, native and over-expressed) in hens and mice models, and 3) demonstrate the hypothesis that one can improve the performance of probiotic strains by cloning the genes of interest in the respective BSH negative mutants. An air and acid tolerant industrial strain, Bifidobacterium lactis clearly identified as probiotic traits that currently used in probiotic yogurts and this presents a challenge as very little genetic expression work has been done. The concept of developing an innovative Bifidobacterium food-grade vector and expression system to advance our understanding of the metabolic activity, gene function, and expression is a novelty that will be useful for researcher and industries to evaluate the probiotic effects.