Shuttle Vectors of Bacillus thuringiensis

Abstract

Bacillus thuringiensis is characterized by the synthesis of parasporal crystals during sporulation; these are composed of one or more highly specific insecticidal or nematocidal endotoxin proteins. Genetic manipulation of B. thuringiensis has been achieved due to the development of stable shuttle vectors and the establishment of efficient transformation systems. Shuttle vectors of B. thuringiensis have been constructed using essentially replicons from resident plasmids from this bacterium that replicate by the theta mechanism. Also, these vectors have been developed using plasmid replicons from other Gram-positive bacteria or RCR plasmids. The transformation of B. thuringiensis with these vectors has been accomplished mainly through electroporation. The development of shuttle vectors with better characteristics and protocols with high transformation efficiency have greatly facilitated basic research and engineering of B. thuringiensis.

Cloning Systems in Bacillus: Bioengineering of Metabolic Pathways for Valuable Recombinant Products

“…Stable shuttle vectors were developed for B. thuringiensis strains to increase their insecticidal activity due to the so-called crystal toxins (encoded by cry genes) typically encoded by large natural plasmids. Examples of such vectors include pHT3101, pHT315, pHBLBIV, and pEMB0557, all of them with two origins of replication: for Gram-negative bacteria (e.g., ori pUC18, ori pBeloBAC11) and for Gram-positive bacteria (e.g., ori pHT1030, ori pBLB, ori p60), both named after the original vectors from which they were derived [26].…”