Insecticidal activity of Bacillus thuringiensis crystal proteins

Martins

et al. 2012

Pesq. agropec. bras.

Resumo -O objetivo deste trabalho foi selecionar e caracterizar estirpes nativas de Bacillus thuringiensis tóxicas a Diatraea saccharalis (Lepidoptera: Crambidae). Cento e seis estirpes pertencentes ao Banco Selection and characterization of Bacillus thuringiensis efficient strains against Diatraea saccharalis (Lepidoptera: Crambidae)Abstract -The objective of this work was to select and characterize native strains of Bacillus thuringiensis toxic to Diatraea saccharalis (Lepidoptera: Crambidae). A hundred-and-six strains, belonging to the bank of invertebrate bacteria (Brazil), of Embrapa Genetic Resources and Biotechnology, were tested as to their toxicity to D. saccharalis, and the most toxic ones were characterized by biochemical and molecular methods. Out of the 106 tested strains, 16 caused 100% mortality within 24 hours. The three most toxic strains showed median lethal concentrations between 8 and 43 ng cm -2 . The protein profile of the 16 strains showed the presence of 130 and 65 kDa proteins, and the molecular characterization showed the presence of cry1and cry2 type genes: cry1Aa, cry1Ab, cry1Ac, and cry2Aa. The median lethal concentration of spores and crystals obtained from recombinant strains, which individually expressed the genes cry1Aa, cry1Ab, cry1Ac, and cry2Aa, varied between 222 and 610 ng cm -2 , values much higher than the ones of the most toxic native strains, which have the possibility of simultaneously expressing these genes. This result indicates a synergy between the toxins. There are interactions between B. thuringiensis toxins and their receptors in the sugarcane borer.

Section: Resultsunclassified

Seleção e caracterização de estirpes de Bacillus thuringiensis eficientes contra a Diatraea saccharalis (Lepidoptera: Crambidae)

Martins

et al. 2012

Pesq. agropec. bras.

“…Lepidoptera pests may be susceptible to Cry1, Cry8, Cry9, Cry15,Cry22, Cry32, and Cry51. Proteins Cry2, Cry3 and Cry22 are toxic to hymenopterans (Van FranKenHuyzen 2009).…”

Section: Introductionmentioning

confidence: 99%

Crystalline protein profiling and cry gene detection in Bacillus thuringiensis strains isolated during epizootics in Cydia pomonella L.

2014

Abstract:The composition of Bacillus thuringiensis crystalline inclusions was characterized in 18 strains: 12 isolates were obtained from the intestinal tract of Cydia pomonella larvae during epizootics, 2 isolates were cultured from Leucoma salicis larvae taken from their natural populations, and 4 reference strains. The number and molecular mass of B. thuringiensis crystalline proteins (Cry and Cyt) was estimated by the sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The crystals contained 1-8 proteins with molecular masses of 36-155 kDa. The toxin profiles differed both quantatively and qualitatively. The B. thuringiensis MPU B9 isolate had the highest number and diversity of Cry toxins. The analysis of crystal composition by SDS-PAGE was insufficient to detect groups and subgroups of Cry proteins. We identified 20 groups and 3 subgroups of Cry and Cyt crystalline toxins. Only one epizootic strain harboured cry25. In single reference strains, the cry1H, cry10 and cry25 genes were found. We did not find any correlation between the occurrence of cry genes and electrophoretic protein profiles of crystalline toxins.

Molecular & Cellular Proteomics

“…Moreover, different strains can produce various ICPs having specific insecticidal activity. To date, B. thuringiensis has been reported to produce over 760 kinds of ICPs that are classified into 72 Cry groups (723 kinds) and 3 Cyt groups (37 kinds) (http://www.lifesci.sussex.ac.uk/Home/ Neil Crickmore/Bt/; November, 2012), which endow it with an extensive spectrum of insecticidal activity (4). Moreover, many studies have confirmed that B. thuringiensis is one of the safest microbial products known (5).…”

mentioning

confidence: 99%

“…Our results, for the first time, systematically reveal the metabolic regulation mechanisms involved in the supply of the amino acids, carbon substances, and energy for spore and parasporal crystal formation at both the transcriptional and translational levels. 4 , 0.5g; glucose, 1.0 g; and yeast extract 2.0 g/L (pH 7.4). Two biological replicate cell samples were collected by centrifugation (6000 ϫ g, 5 min, 4°C) at 7 h, 9 h, 13 h, and 22 h. Each sample was divided into two parts for whole-genome transcriptomics and proteomics analyses.…”

mentioning

confidence: 99%

The Metabolic Regulation of Sporulation and Parasporal Crystal Formation in Bacillus thuringiensis Revealed by Transcriptomics and Proteomics

Wang

Han

Cao

et al. 2013

Bacillus thuringiensis is a well-known entomopathogenic bacterium used worldwide as an environmentally compatible biopesticide. During sporulation, B. thuringiensis accumulates a large number of parasporal crystals consisting of insecticidal crystal proteins (ICPs) that can account for nearly 20 -30% of the cell's dry weight. However, the metabolic regulation mechanisms of ICP synthesis remain to be elucidated. In this study, the combined efforts in transcriptomics and proteomics mainly uncovered the following 6 metabolic regulation mechanisms: (1) proteases and the amino acid metabolism (particularly, the branched-chain amino acids) became more active during sporulation; (2) stored poly-␤-hydroxybutyrate and acetoin, together with some low-quality substances provided considerable carbon and energy sources for sporulation and parasporal crystal formation; (3) the pentose phosphate shunt demonstrated an interesting regulation mechanism involving gluconate when CT-43 cells were grown in GYS medium; (4) the tricarboxylic acid cycle was significantly modified during sporulation; (5) an obvious increase in the quantitative levels of enzymes and cytochromes involved in energy production via the electron transport system was observed; (6) most F 0 F 1 -ATPase subunits were remarkably up-regulated during sporulation. This study, for the first time, systematically reveals the metabolic regulation mechanisms involved in the supply of amino acids, carbon substances, and energy for B. thuringiensis spore and parasporal crystal formation at both the transcriptional and translational levels. Molecular & Cellular Proteomics