Cloning and expression of the Bacillus sphaericus 2362 mosquitocidal genes in a non-toxic unicellular cyanobacterium, Synechococcus PCC6301.
Genes encoding the mosquitocidal binary toxin of Bacillus sphaericus 2362 were introduced into Synechococcus PCC6301, a cyanobacterium that can tolerate a number of potential variations in the mosquito breeding environment, and can serve as a food source for mosquito larvae. The toxin genes, preceded by a Synechococcus rbcL promoter, were located on a mobilizable Escherichia coli Synechococcus shuttle vector, which was introduced into Synechococcus PCC6301 at frequencies of 10(-5)-10(-7) exconjugants/recipient, depending on the selective conditions used. Recombinant Synechococcus exhibited significant toxicity against 2-day-old and 6-day-old Culex quinquefasciatus larvae, the concentration required to kill 50% of larvae (LC50) being 2.1 x 10(5) and 1.3 x 10(5) cells/ml respectively. Mosquitocidal activity decreased tenfold after 20 generations of non-selective growth.
Sangthongpitag
K
K
Department of Biotechnology, University of New South Wales, Sydney, Australia.
Penfold
R J
RJ
Delaney
S F
SF
Rogers
P L
PL
D000818:Animals; D001407:Bacillus / Q000235:genetics* / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism* / Q000633:toxicity; D001681:Biological Assay; D015153:Blotting, Western; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D009033:Culicidae; D000458:Cyanobacteria / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D005822:Genetic Vectors; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D051379:Mice; D011401:Promoter Regions, Genetic; D011995:Recombination, Genetic
D001427:Bacterial Toxins