Construction of a genomic library in Bifidobacterium longum B2

Abstract- Bifidobacterium longum is a typical species of human digestive tract. It believes to contribute to well being and so it is considered a probiotic species. Adhesion is an impor-tant prerequisite in the probiotic selections so we study the link between this phenotype and molecular aspects of the surface of this species. After a preliminary screening of several strains for their adhesive properties, we made SDS-PAGE of total extract and we found a protein more express in hydrophobic strains than in hydrophilic ones. A genomic library in Bifidobacterium longum B2 was constructed. So we choose the strain B2 which shows a great expression of this protein. We made the SDS-PAGE of cell wall associated proteins to localize it. This protein has a Mr of approximately 160 KDa. In order to clone the DNA sequence we made a genomic library of this strain. Then we immunoscreened the library and we obtained three positive plaques. Key words: Bifidobacterium longum, genomic library, adhesion, immunoscreening