PCR-based identification of Bacillus thuringiensis pesticidal crystal genes

Abstract

The polymerase chain reaction (PCR) is a molecular tool widely used to characterize the insecticidal bacterium Bacillus thuringiensis. This technique can be used to amplify specific DNA fragments and thus to determine the presence or absence of a target gene. The identification of B. thuringiensis toxin genes by PCR can partially predict the insecticidal activity of a given strain. PCR has proven to be a rapid and reliable method and it has largely substituted bioassays in preliminary classification of B. thuringiensis collections. In this work, we compare the largest B. thuringiensis PCR-based screenings, and we review the natural occurrence of cry genes among native strains. We also discuss the use of PCR for the identification of novel cry genes, as well as the potential of novel technologies for the characterization of B. thuringiensis strains.

Diversity of <i>Bacillus thuringiensis</i> strains isolated from coffee plantations infested with the coffee berry borer <i>Hypothenemus hampei</i>

“…The most common cry genes found in nature are those within the cry1 subfamily (Porcar and Juárez-Pérez 2003). The most abundant gene found in our collection was cry2, and the second most abundant was the cry1 gene family.…”

“…The identification of Bt cry genes by PCR has proven to be a very useful method for strain characterization and selection (Porcar and Juárez-Pérez, 2003). In addition Carozzi et al (1991) found correspondence of toxicity with the amplification of particular cry gene profiles, introducing PCR as a tool to predict B. thuringiensis insecticidal activity.…”

Identification and bioactivity of native strains of Bacillus thuringiensis from grain-related habitats in Turkey

“…Strains in the collections are characterized by a number of different methods to identify and to test and confirm their toxicity against different insect orders (Arango et al, 2002;Wang et al, 2003;Tamez-Guerra et al, 2004;Martinez et al, 2005). Identification of cry gene content by PCR is the most effective technique in screening large native collections to predict insecticidal activities of individual strains (Ben-Dov et al, 1997;Porcar and Juarez-Perez, 2002). In addition, serolog-ical analysis, biological activity tests, plasmid contents, chromosomal DNA, and protein profiling are used as complementary methods in the search for novel strains.…”

Characterization and Biological Activity of Bacillus thuringiensis Isolates that Are Potentially Useful in Insect Pest Control

“…Identification of cry genes by means of PCR has been used to predict insecticidal activity of the strains [17,18] and to determine the distribution of cry genes within a collection of B. thuringiensis strains [20,33]. In this context, our crystalliferous strains were characterized in terms of presence of cry1 and cry2 genes by amplification with general primers.…”

“…The literature data report the possibility of using the whole-cell protein profile as a discriminating method with potency similar to RAPD with combined DNA patterns [1]. However, there is not always a good correlation between these factors and insecticidal activity of Bt strains [20,21]. In addition, there is a need to develop knowledge about the biological properties and diversity of Bt isolates since these data allow a better understanding of the biological factors that determine insecticidal properties.…”