A 2.2-kb fragment containing a replicon from pBtoxis, the large plasmid that encodes the insecticidal endotoxins of Bacillus thuringiensis subsp. israelensis, was identified, cloned, and sequenced. This fragment contains cis elements, including iterons, found in replication origins of other large plasmids and suggests that pBtoxis replicates by a type A theta mechanism. Two genes, pBt156 and pB...

A region of DNA which determined the production of the insecticidal toxin of Bacillus thuringiensis subsp. israelensis was cloned into a derivative of a broad-host-range group IncQ plasmid vector of gram-negative bacteria. The plasmid which we constructed was transferred by conjugative mobilization into a Bradyrhizobium species that nodulates pigeon peas. In this species the construction was ma...

The mosquitocidal glycoprotein endotoxin of Bacillus thuringiensis subsp. israelensis was digested with chymotrypsin to yield protease-resistant domains which were then separated from smaller protease digestion products by high-performance liquid chromatography. Once purified, the domains no longer bound wheat germ agglutinin, a lectin which binds N-acetylglucosamine (GlcNAc) and GlcNAc oligome...

We recently identified a minireplicon of pBtoxis from Bacillus thuringiensis subsp. israelensis that contained an operon encoding two novel proteins (ORF156 and ORF157), both of which are required for replication. ORF157 contains a helix-turn-helix motif and shares no homology with known plasmid replication proteins (Rep), and ORF156 contains the signature motif present in FtsZ/tubulin proteins...

The impact of promoter modification on the expression of the mosquitocidal Bacillus thuringiensis subsp. israelensis cryIVB gene when used to transform the cyanobacterium Synechococcus sp. strain PCC 7942 has been examined. Maximal transcript and protein abundances were achieved by the addition of the lacZ promoter upstream of the cryIVB sequence. Replacement of the endogenous corresponding Bac...

Mendelian crosses were used to analyze the patterns of inheritance of Cry-toxin resistance in two colonies of Culex quinquefasciatus Say larvae resistant to bacterial toxins produced by Bacillus thuringiensis subsp. israelensis de Barjac. Resistance levels exceeded 1000-fold at 95% lethal concentration of the CryllAa-resistant colony (Cq11A). F1 offspring of reciprocal crosses to a susceptible ...

The effects of two widespread environmental pollutants, perchlorate and hexavalent chromium, were assessed on the efficacy of Bacillus thuringiensis subsp. israelensis (Bti) and Bacillus sphaericus (Bsph) against fourth instars of Culex quinquefasciatus Say (Diptera: Culicidae) in 24-h laboratory bioassays. Although 250 mg/liter perchlorate, a level somewhat higher than would be considered ecol...

In the same way that cry genes, coding for larvicidal delta endotoxins, constitute a large and diverse gene family, the cyt genes for hemolytic toxins seem to compose another set of highly related genes in Bacillus thuringiensis. Although the occurrence of Cyt hemolytic factors in B. thuringiensis has been typically associated with mosquitocidal strains, we have recently shown that cyt genes ar...

Cry11A from Bacillus thuringiensis subsp. israelensis and Cry11Ba from Bacillus thuringiensis subsp. jegathesan were introduced, separately and in combination, into the chromosome of Bacillus sphaericus 2297 by in vivo recombination. Two loci on the B. sphaericus chromosome were chosen as target sites for recombination: the binary toxin locus and the gene encoding the 36-kDa protease that may b...