There are a diverse number of naturally-occurring Lactobacillus species found in the human GI tract and many are considered to exert beneficial roles there. Establishing these roles, individually and in combination, remains a significant challenge. Realization of the genome content of one major species of intestinal lactobacilli will provide key insights toward understanding their capabilities, roles, and interactions. Functional analysis of gene content and expression will be greatly accelerated and is expected to provide key insights to the survival, roles, and potential benefits of this group of commensal organisms. Relative to the other members of the acidophilus complex, there exists a significant platform of work on the L. gasseri species related to its transformability by electroporation (Luchansky et al., 1988), expression of heterologous genes (Cho et al., 2000), and the available genome sequence information for one temperate bacteriophage (Altermann et al., 1999; Raya et al., 1992). L. gasseri is substantially more amenable to DNA introduction and manipulation which has lead to the development of more genetic tools that will be useful in the functional genomic analysis of this species (Kullen and Klaenhammer, 1999; Russell and Klaenhammer, 2001).
This project and accompanying efforts of the Lactic Acid Bacteria Genomics Consortium will carry out genome sequencing of a number of Lactobacillus species, some with considerable diversity in ecological habitat (milk, meat, plants, GI tract) and roles (probiotic versus fermentation of plants, milk, wine). Comparative genomic analysis between the various Lactobacillus species that occupy the GI tract is expected to identify important regions that are necessary for survival and activity in this environment. In addition, comparative genomics of intestinal lactobacilli with other lactic acid bacteria, from distinctive environments will hopefully identify the regions that are involved in the adaptation of lactobacilli to many specialized and varied environments, including the GI tract.
Contributed by Todd R. Klaenhammer
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