Distribution of <i>cry</i> and <i>cyt</i> Genes among Indigenous <i>Bacillus thuringiensis</i> Isolates with Mosquitocidal Activity

Abstract

Bacillus thuringiensis strains isolated from Madurai, TamilNadu, India were evaluated for their mosquitocidal activity, as well as cry and cyt genes diversity. It revealed that 99% of the parasporal crystal morphology of these isolates was spherical in nature and a variable percentage (0%-100%) of toxicity was observed against Culex quinquefasciatus and Aedes aegypti. PCR analysis revealed that 53% of the isolates were positive for the various cry and cyt genes tested, whereas 47% did not produce any PCR product for the cry gene analyzed. Diverse pattern of cry and cyt genes distribution was observed even in the isolates from the same sample. B. thuringienis subsp. LDC-9 showed threefold higher toxicity against Culex quinquefasciatus than that of B. thuringiensis var israelensis which might be used as a potential strain to control mosquitoes in near future after field evaluation.

Isolation and characterization of native Bacillus thuringiensis strains from Saudi Arabia with enhanced larvicidal toxicity against the mosquito vector Anopheles gambiae (s.l.)

“…Each of these 23 isolates and the Bti -H14 strain were tested for positive amplification of the cry and cyt and chi genes specific to Diptera using a battery of previously-described universal and specific primers [25, 31–34] (Additional file 2: Table S2). All examined isolates yielded amplicons of the predicted size for cry4 , cry11 , cyt1 and cyt2 (Fig.…”

“…Oligonucleotide primers were synthesized in a DNA synthesizer (Applied Biosystems, Foster City, CA, USA) using the manufacturer’s instructions. PCR amplifications were performed as previously described [25] and the resulting amplicons were visualized by running the PCR products (15μl) on 2% agarose electrophoretic gels as described in Mahalakshmi et al [34]. …”

Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria

“…For example, the expression of cry4 , cry10 , or cry11 genes give rise to spherical shape crystals, and their respective proteins are known to be active against Diptera [73,74,75,76]. Crystals with a bipyramidal shape result from the accumulation of Cry1 or Cry9 proteins, which are active mainly against Lepidoptera [24,77,78].…”

Characterization of a native Bacillus thuringiensis isolates from Malaysia that produces exosporium-enclosed parasporal inclusion

“…In addition to smooth colonies with irregular shape, Lima et al (2002) also characterized a B. thuringiensis isolate that produced dark yellowish colonies. Apart from the characteristics stated, many also reported that B. thuringiensis strains formed "fried-egg" appearance on agar plate (Travers et al, 1987;El-kersh et al, 2012;Mahalakshmi et al, 2012). The descriptions for colony morphology are very subjective.…”