title: Relationship between plasmid loss and gene expression in Bacillus thuringiensis.
abstract: The large genome of Bacillus thuringiensis was shortened by provoking plasmid loss, and the effect of such loss on the expression of both chromosomal and plasmid-harboured genes was studied. It was evidenced that the genomic material shortening of B. thuringiensis allows for the improvement of the expression of some of the constructive genes. Indeed, it was shown that curing was an efficient tool to obtain mutant strains with better expression of chromosomal genes. In fact, totally cured strains, HD1Cry-B and BNS3Cry, showed higher chitinolytic and/or proteolytic activities than the corresponding wild and/or partially cured ones. Although total curing is drastic for plasmid-harboured gene expression, the authors obtained partially cured strains, Cur255 and CurHD1, with a doubled level of delta-endotoxin production, and a 1.5-fold improvement of the bacteriocin-specific activity, respectively. In addition, the latter strains showed better relative proteolytic activities.
authors.affiliation: Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, PO Box 1177, 3018 Sfax, Tunisia.
authors.forename: Fatma
authors.initials: F
authors.lastname: Driss
authors.forename: Slim
authors.initials: S
authors.lastname: Tounsi
authors.forename: Samir
authors.initials: S
authors.lastname: Jaoua
mesh_terms: D001413:Bacillus thuringiensis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins