Strain of Bacillus thuringiensis from Restinga, toxic to Aedes (Stegomyia) aegypti (Linnaeus) (Diptera, Culicidae)

Abstract

Bacillus thuringiensis is the most commonly used entomopathogen in the control of Aedes aegypti, which is a vector for different etiological agents that cause serious infections in humans. Several studies aim to isolate strains of this bacterium from different environments, with the perspective of selecting isolates with larvicidal activity for mosquitoes. Aiming at the insecticidal action of B. thuringiensis, the present study aimed to prospect B. thuringiensis of restinga and mangrove soils from the state of Maranhão, Brazil, with toxic potential for use in the biological control of Ae. aegypti. Bioassays were performed to determine the entomopathogenic activity of the bacilli against Ae. aegypti and lethal concentrations (LC50 and CL90) were estimated after the tests. Polymerase Chain Reaction and SDS-PAGE techniques were performed to verify the gene and protein content of the isolates, respectively. The soil of the mangrove and restinga ecosystems showed potential for obtaining B. thuringiensis. This isolate, in addition to having proteins with molecular mass similar to the toxins Cry and Cyt, also presented several diptera-specific genes cry and cyt, demonstrating that it has high potential to be used in the biological control of Ae. aegypti.

Genetic diversity of Brazilian Bacillus thuringiensis isolates with toxicity against Aedes aegypti (Diptera: Culicidae)

“…The BtMA isolates showed a great diversity of the diptera-specific genes cry4, cry10, cry11, cyt1 and cyt2 52,34,59 . Groups V and VI included BtMA isolates with all the investigated genes, with the exception of the BtMA-694 isolate from group V, which did not amplify the cyt2Ba gene, and the BtMA-689 isolate from group VI, which did not amplify the cry11Ba gene.…”

“…(BtMA) obtained from soil samples and with high toxicity to A. aegypti larvae amplified for cry (cry4Aa, cry4Ba, cry10Aa, cry11Aa and cry11Ba) and cyt (cyt1Aa, cyt1Ab, cyt2Aa and cyt2Ba) 52,34,59 and seven standard subspecies of Bt were used in this survey (Tables 1 and 2 3). Amplification was accomplished with the Gencycler-G96G thermocycler (Biosystems), following the standard program at 94 °C for 5 min; 36 cycles at 94 °C for 1 min; annealing (with temperatures varying for each primer) for 1 min; extension at 72 °C for 2 min; and final extension at 72 °C for 7 min.…”

Relations between soil attributes and the abundance of Bacillus thurigiensis in the Cerrado of Maranhão state, Brazil

“…However, new Bacillus thuringiensis strains with high toxicity rate to A. aegypti have been found in Atlantic Forest soils (Santos et al, 2012). Similarly, other authors have collected them in Cerrado, Amazon and Caatinga soils (Soares-da-Silva et al, 2015), in restinga and mangrove soils (Vieira-Neta et al, 2021) and continue to raise Soil fertility and the abundance of Bacillus thurigiensis randomly, and each sub-sample being 10 m apart, to form a composite sample in each area, three areas of native Cerrado forest per municipality being surveyed (sampled), totaling 15 total samples. The soil was collected using a Dutch auger, also used for the analysis of chemical and texture attributes, and specifically for the analysis of Bacillus thuringiensis; a wooden spatula was used for soil collection, with subsequent storage in previously sterilized Falcon-type centrifuge tubes.…”

Fixation of pfcrt chloroquine resistance alleles in Plasmodium falciparum clinical isolates collected from unrest tribal agencies of Pakistan

“…Both encode trans-membrane CQ transporter proteins present on the membrane of P. falciparum digestive vacuole. These transporter proteins are responsible for the transport and gathering of CQ in the parasite's food vacuole, which is the site for CQ action, while mutations in these genes alter the efflux of CQ from the intracellular digestive vacuole (Plowe, 2009;Vieira-Neta et al, 2021). Resistance to CQ is mediated by mutations at codons 72-76 (C72S/R, M74I/T, N75E/D/K/I, and K76T/I/N) P. falciparum Pfcrt gene, results in amino acid substitutions from wild type CVMNK to two most prevalent mutant haplotypes CVIET and SVMNT present in African and South-East Asian countries respectively.…”