Molecular characterization of Bacillus thuringiensis strains from Argentina

Abstract

Bacillus thuringiensis INTA 7-3, INTA 51-3, INTA Mo9-5 and INTA Mo14-4 strains were obtained from Argentina and characterized by determination of serotype, toxicity, plasmid composition, insecticidal gene content ( cry and vip ) and the cloning of the single- vip3A gene of the INTA Mo9-5 strain. The serotype analysis identified the serovars tohokuensis and darmstadiensis for the INTA 51-3 and INTA Mo14-4 strains, respectively, whereas the INTA Mo9-5 strain was classified as "autoagglutinated". In contrast to the plasmid patterns of INTA 7-3, INTA 51-3 and INTA Mo9-5 (which were similar to B. thuringiensis HD-1 strain), strain INTA Mo14-4 showed a unique plasmid array. PCR analysis of the four strains revealed the presence of cry genes and vip3A genes. Interestingly, it was found that B. thuringiensis 4Q7 strain, which is a plasmid cured strain, contained vip3A genes indicating the presence of these insecticidal genes in the chromosome. Bioassays towards various lepidopteran species revealed that B. thuringiensis INTA Mo9-5 and INTA 7-3 strains were highly active. In particular, the mean LC(50) obtained against A. gemmatalis larvae with the INTA Mo9-5 and INTA 7-3 strains were 7 (5.7-8.6) and 6.7 (5.6-8.0) ppm, respectively. The INTA Mo14-4 strain was non-toxic and strain INTA 51-3 showed only a weak larvicidal activity.

Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria

“…Genes coding for Vip3 proteins are commonly found among B. thuringiensis strains, and hence, some studies have even found them in 50% and up to 87% of the strains tested and in Ͼ90% of strains carrying cry1 and cry2 genes (20,21,(40)(41)(42)(43)(44). vip3 genes are ϳ2.4 kb in length, and they are normally carried on large plasmids (43,45), although in some cases, they have been proposed to be located in the bacterial chromosome (46). Many strategies for screening of B. thuringiensis isolates have been performed with the aim of isolating new vip3 genes (19,20,25,42,(46)(47)(48)(49)(50)(51)(52).…”

“…vip3 genes are ϳ2.4 kb in length, and they are normally carried on large plasmids (43,45), although in some cases, they have been proposed to be located in the bacterial chromosome (46). Many strategies for screening of B. thuringiensis isolates have been performed with the aim of isolating new vip3 genes (19,20,25,42,(46)(47)(48)(49)(50)(51)(52). At the time of writing of this review, there have been 54 vip3Aa, 2 vip3Ab, 1 vip3Ac, 4 vip3Ad, 1 vip3Ae, 3 vip3Af, 15 vip3Ag, 1 vip3Ah, 1 vip3Ai, 2 vip3Ba, 3 vip3Bb, and 4 vip3Ca genes reported (9).…”

Distribution of Genes Encoding Putative Virulence Factors and Fragment Length Polymorphisms in the vrrA Gene among Brazilian Isolates of Bacillus cereus and Bacillus thuringiensis

“…Conversely, evidence indicating that the gene is chromosomally located has been presented (16), although that conclusion was based on the examination of a single isolate. The widely divergent values recorded for carriage of this gene among strains of B. thuringiensis may indicate that the acquisition of this gene, possibly via horizontal gene transfer from other soil microbes, was a relatively recent event in the evolution of B. thuringiensis.…”

Identification, Cloning and Expression of an Insecticide <b><i>cry8</i></b> Gene from <b><i>Bacillus</i></b><b><i>thuringiensis </i></b>INTA Fr7-4

“…In the long term, our goal is to find new insecticidal proteins from the local B. thuringiensis insecticidal gene pool to serve as a supply for the development of new tools for crop protection. The entries of the collection have been characterized to different extents [e.g., Benintende et al, 2000;Franco-Rivera et al, 2004;Sauka et al, 2010a].…”