scholarly journals Isolation of Bacillus thuringiensis strains that contain Dipteran-specific cry genes from Ilha Bela (São Paulo, Brazil) soil samples

2012 ◽  
Vol 72 (2) ◽  
pp. 243-247 ◽  
Author(s):  
EB. Campanini ◽  
CC. Davolos ◽  
ECC. Alves ◽  
MVF. Lemos
Keyword(s):  
Biological Control ◽  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Ribosomal Subunit ◽  
Soil Samples ◽  
Bacterial Isolates ◽  
Cry Genes ◽  
Cry Proteins ◽  
Crystal Proteins ◽  
Bacterium Bacillus

The entomophatogenic bacterium Bacillus thuringiensis produces crystal proteins, named Cry proteins which are encoded by the cry genes. This bacterium is used on biological control of important economical pests, as well as in the control of disease´s vectors, such as Aedes aegypti, a mosquito that transmits the dengue viruses. Isolates of this bacterium can be characterized by the content of cry genes and this prediction helps target different insect orders. In this research, we isolated 76 colonies of B. thuringiensis from 30 soil samples that were taken from Ilha Bela (SP, Brazil), a place where simulids are already biologically controlled by B. thuringiensis, to find bacterial isolates that were capable of controlling A. aegypti. The 16S ribosomal subunit genes of the selected isolates were sequenced, and the isolates were molecularly characterized based on their Dipteran-specific cry gene contents. Eight of the 76 isolates (10.52%) contained the cry4Aa, cry4Ba or cry10Aa genes, these isolates were carried out against A. aegypti larvae on bioassay. The presence or absence of specific cry genes was associated with the observed average larval mortalities. From the 76 isolates, seven (9.2%) were potentially able to control A. aegypti larvae. Therefore these are promising isolates for the biological control of A. aegypti larvae.

scholarly journals Fatores de virulência de Bacillus thuringiensis: o que existe além das proteínas Cry

2012 ◽  
Vol 5 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Gislayne Trindade Vilas-Bôas ◽  
Rita C. Alvarez ◽  
Clelton A. Dos Santos ◽  
Laurival A. Vilas-Boas
Keyword(s):  
Biological Control ◽  
Bacillus Thuringiensis ◽  
Virulence Factors ◽  
Insect Pests ◽  
Cry Proteins ◽  
Control Programs ◽  
Wide Range ◽  
Vip Proteins ◽  
Bacterium Bacillus ◽  
And Control

As proteínas Cry produzidas pela bactéria entomopatogênica Bacillus thuringiensis Berliner são bem conhecidas devido a alta citotoxicidade que exibem a uma variedade de insetos-alvo. O modo de ação destas proteínas é específico e torna os produtos à base de B. thuringiensis os mais amplamente utilizados em programas de controle biológico de pragas na agricultura e de importantes vetores de doenças humanas. Contudo, embora as proteínas Cry sejam os fatores de virulência inseto-específico mais conhecidos, linhagens de B. thuringiensis apresentam também uma ampla gama de fatores de virulência, os quais permitem à bactéria atingir a hemolinfa e colonizar eficientemente o inseto hospedeiro. Dentre estes fatores, destacam-se as proteínas Vip, Cyt, enterotoxinas, hemolisinas, fosfolipases, proteases, enzimas de degradação, além das recentemente descritas parasporinas. Essa revisão aborda a ação desses fatores de virulência, bem como a caracterização e o controle da expressão de seus genes. Adicionalmente, são discutidos aspectos relacionados ao nicho ecológico da bactéria com ênfase nas características envolvidas com a biossegurança da utilização dos produtos à base de B. thuringiensis para o controle biológico de insetos-alvo. Virulence Factors of Bacillus thuringiensis Berliner: Something Beyond of Cry Proteins? Abstract. The Cry proteins produced by the entomopathogenic bacterium Bacillus thuringiensis Berliner are widely known due to its high toxicity against a variety of insects. The mode of action of these proteins is specific and becomes B. thuringiensis-based products the most used in biological control programs of insect pests in agriculture and of important human disease vectors. However, while the Cry proteins are the best-known insect-specific virulence factor, strains of B. thuringiensis show also a wide range of other virulence factors, which allow the bacteria to achieve the hemolymph and colonize efficiently the insect host. Among these factors, we highlight the Vip proteins, Cyt, enterotoxins, hemolysins, phospholipases, proteases and enzymes of degradation, in addition to the recently described parasporin. This review explores the action of these virulence factors, as well as, the characterization and control of expression of their genes. Additionally, we discuss aspects related to the ecological niche of the bacteria with emphasis on the characteristics involved in the biosafety of the use of B. thuringiensis-based products for biological control of target insects.

scholarly journals THE USE OF AGENTS BASED ON THE BACTERIUM BACILLUS THURINGIENSIS VAR. ISRAELENSIS FOR MOSQUITO CONTROL

2019 ◽  
Vol 98 (8) ◽  
pp. 893-896
Author(s):  
Svetlana A. Roslavtseva
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Synergistic Effect ◽  
Mosquito Control ◽  
Mosquito Species ◽  
Bacillus Sphaericus ◽  
Development Of Resistance ◽  
Blood Sucking ◽  
Low Concentrations ◽  
Bacterium Bacillus

Mosquito control is necessary to improve the epidemic and, consequently, the sanitary and hygienic situation in human settlements. At the same time, the safest and more environmentally friendly way of controlling is not the fight against adult mosquitoes, but the treatment of reservoirs with microbiological larvicides based on entomopathogenic, aerobic, spore-forming, saprophytic bacteria Bacillus thuringiensis (de Barjac) (Bti). A new serotype of the bacterium B. thuringiensis was found in Israel in the Negev desert. This serotype being more active against larvae of blood-sucking and non-blood-sucking mosquitoes and midges than previously known serotypes, was named israelensis. Bti endotoxin is a typical insecticide with intestinal type of action for different mosquito species. For example, Bti H14 is highly insecticidal to the larvae of Aedes aegypti and Ae. albopictus at very low concentrations. The parasporal body (endotoxin crystal), a crystalline protein consisted of four main polypeptides and two minor polypeptides, possesses of a larvicidal action. Larvicidal activity is associated with a synergistic effect in a combination of four polypeptides. The possibility of development of resistance to products based on Bti and Bacillus sphaericus in populations of mosquitoes (Culicidae) was investigated. The use of domestic microbiological formulations based on Bti («Baktitsid», «Larviol-pasta», and «Antinat») was shown an eradication the larvae of bloodsucking mosquitoes and midges to be possible and rational, since they are not generated resistant populations of mosquitoes. This is confirmed by more than 30 years of the use of such formulations.

scholarly journals Bacillus thuringiensis and Its Pesticidal Crystal Proteins

1998 ◽  
Vol 62 (3) ◽  
pp. 775-806 ◽  
Author(s):  
E. Schnepf ◽  
N. Crickmore ◽  
J. Van Rie ◽  
D. Lereclus ◽  
J. Baum ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Integrated Management ◽  
Management Strategies ◽  
Resistance Mechanisms ◽  
Maximum Efficiency ◽  
Crystal Proteins ◽  
Evolution Of Resistance ◽  
Complex Relationships ◽  
Bacterium Bacillus ◽  
Natural Settings

SUMMARY During the past decade the pesticidal bacterium Bacillus thuringiensis has been the subject of intensive research. These efforts have yielded considerable data about the complex relationships between the structure, mechanism of action, and genetics of the organism’s pesticidal crystal proteins, and a coherent picture of these relationships is beginning to emerge. Other studies have focused on the ecological role of the B. thuringiensis crystal proteins, their performance in agricultural and other natural settings, and the evolution of resistance mechanisms in target pests. Armed with this knowledge base and with the tools of modern biotechnology, researchers are now reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.

scholarly journals Development of a Low Cost Bioprocess for Endotoxin Production by Bacillus thuringiensis var israelensis Intended for Biological Control of Aedes aegypti

2009 ◽  
Vol 52 (spe) ◽  
pp. 121-130 ◽  
Author(s):  
Carlos Ricardo Soccol ◽  
Teresinha E. V. Pollom ◽  
Ricardo Cancio Fendrich ◽  
Fernando Alberto Prochmann ◽  
Radijiskumar Mohan ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Reference Strain ◽  
Low Cost ◽  
Growth Period ◽  
Toxin Production ◽  
Sugarcane Molasses ◽  
Dengue Disease ◽  
Crystal Proteins ◽  
Low Activity

Aedes aegypti is the vector of Dengue disease, responsible for 20,000 deaths/year worldwide. Bacillus thuringiensis var israelensis - Bti releases selective and effective toxins (crystal proteins) against A. aegypti larvae. We present a low cost bioprocess for toxin production, accomplished by a selected Brazilian strain Bti (BR-LPB01) and employment of low cost substrates. Soybean meal and sugarcane molasses lead to high toxic effectiveness after 2L bioreactor fermentation (LD50=26ng/mL), near to the reference strain IPS82 (LD50=17.3 ng/mL). The pH ranged between 5.8 and 7.0 during the exponential growth period and between 7.0 and 8.4 during the stationary phase, with low activity. Thus, control of foam and pH 7.0 were started and proved to be crucial for high activity. It was verified that the fermentation could be discontinued after 20 hours, when the highest activity was present.

scholarly journals Diversity of Insecticidal Crystal proteins (ICPs) of indigenous Bacillus thuringiensis strains

2018 ◽  
Vol 5 ◽  
pp. 11-18
Author(s):  
Ganga G.C. ◽  
Charu Arjya ◽  
Yamuna Khadka ◽  
Sabina Dhamala
Keyword(s):  
Bacillus Thuringiensis ◽  
Slight Modification ◽  
Soil Samples ◽  
Colony Morphology ◽  
Selective Enrichment ◽  
Crystal Proteins ◽  
Selection Protocol ◽  
White Type ◽  
Insecticidal Crystal Proteins

Objectives: The purpose of this study was to characterize the indigenous Bacillus thuringiensis (Bt) isolated from the soil samples of central development region of Terai. Methods: A total of 50 soil samples collected from cultivated and barren fields of Terai region. Isolation was carried out using the acetate selection protocol as described by (Russell and Al 1987) with a slight modification. The Nutrient broth (NB) was acetated by using 0.25M sodium acetate which is a selective enrichment method for isolation of Bt. Characterization of the isolate was done by phenotyping methods (microscopy and biochemical). Results: No distinct variation was observed between the isolates of cultivable and uncultivable lands. Bt were categorized into7 different types based on colony morphology. The dominant colony was fried egg type identical with the reference strain, followed by flat white type of colony. The result showed that even though the colony morphology is same but the ICPs (Insecticidal crystal proteins) shapes produced by them vary, rod shapes (53.57%), spherical (10.71%), ovoid (8.3%), amorphous (17.85%), capheaded (9.5%). ICPs morphology reveal the cry1, cry2, cry3, cry4, cry8, cry 9, cry10 and cry11 types of gene may be present in the native isolates. Conclusion: This study represents the first report of several indigenous Bacillus thuringiensis strains with significantly different ICPs producing stains from hot tropical climate.

scholarly journals Evaluating Cross-resistance Between Vip and Cry Toxins of Bacillus thuringiensis

2019 ◽  
Vol 113 (2) ◽  
pp. 553-561 ◽  
Author(s):  
Bruce E Tabashnik ◽  
Yves Carrière
Keyword(s):  
Bacillus Thuringiensis ◽  
Genetically Engineered ◽  
Cross Resistance ◽  
Published Data ◽  
Data Sets ◽  
Cry Proteins ◽  
Cry Toxins ◽  
Bt Crops ◽  
Resistant Strains ◽  
Bacterium Bacillus

Abstract Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized control of some major pests. Some recently introduced Bt crops make Vip3Aa, a vegetative insecticidal protein (Vip), which reportedly does not share binding sites or structural homology with the crystalline (Cry) proteins of Bt used widely in transgenic crops for more than two decades. Field-evolved resistance to Bt crops with practical consequences for pest control includes 21 cases that collectively reduce the efficacy of nine Cry proteins, but such practical resistance has not been reported yet for any Vip. Here, we review previously published data to evaluate cross-resistance between Vip and Cry toxins. We analyzed 31 cases based on 48 observations, with each case based on one to five observations assessing cross-resistance from pairwise comparisons between 21 resistant strains and 13 related susceptible strains of eight species of lepidopteran pests. Confirming results from previous analyses of smaller data sets, we found weak, statistically significant cross-resistance between Vip3 and Cry1 toxins, with a mean of 1.5-fold cross-resistance in 21 cases (range: 0.30–4.6-fold). Conversely, we did not detect significant positive cross-resistance between Vip3 toxins and Cry2Ab. Distinguishing between weak, significant cross-resistance, and no cross-resistance may be useful for better understanding mechanisms of resistance and effectively managing pest resistance to Bt crops.

scholarly journals Efficacy of 2 Commercial Formulations of Bacillus thuringiensis H-14 in Larvae of Anopheles albimanus W and Aedes aegypti L (Diptera: culicidae).

2020 ◽  
Author(s):  
Victoriano Garza-Almanza ◽  
Gérard Ulíbarri ◽  
Juan Manuel Sanchez-Yañez
Keyword(s):  
Biological Control ◽  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Efficient Method ◽  
Mosquito Control ◽  
Mosquito Vectors ◽  
Anopheles Albimanus ◽  
Vector Species ◽  
Bacterial Genus ◽  
Wettable Powder

The bacterial genus and species of Bacillus thuringiensis var israelensis (Bti), is entomotoxic, used in the biological control of mosquito vectors of human diseases, such as malaria and dengue. Following the studies carried out in Mexico and Guatemala with ovillantas, in which the presence of larvae of both species of Anopheles albimanus W and Aedes aegypti L were observed, and with the intention of continuing to develop an ecologically friendly mosquito control, Bti was added to the ovillantas, to improve and already efficient method on the elimination of both types of mosquitoes. The objectives of this work were: to analyze the effectiveness of two commercial formulations of Bti, serovar H-14 (Bactimos) wettable powder, 3,500 ITU, from Biochem prods., and Vectobac, 2,000 ITU wettable powder, (Abbot Lab.) on second and third instars larvae of A. albimanus and Ae. aegypti (Diptera Culicidae). The two formulations were effective against A. albimanus W(higher concentrations), while Ae. aegypti L was very susceptible to Bti, therefore it is proposed for the best control of these genus and vector species of malaria and dengue at adequate concentrations.

scholarly journals Bioprospecting of Bacillus thuringiensis in the control of Aedes aegypti larvae

2020 ◽  
Vol 7 (16) ◽  
pp. 175-191
Author(s):  
Aline Souza Soares ◽  
Lara Teixeira Melo Costa ◽  
Cristina Almeida da Silva ◽  
Suetônio Fernandes dos Santos ◽  
Raimundo Wagner de Souza Aguiar
Keyword(s):  
Biological Control ◽  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Chemical Control ◽  
Alternative Methods ◽  
Scientific Society ◽  
Risk Of Death ◽  
Disease Vector ◽  
Imminent Risk ◽  
Methods Of Control

Aedes aegypti (Diptera: Culicidae) is the main vector of Dengue, Zika and Chikungunya, diseases that have attracted the attention of scientific society and the population in general, due to epidemiological outbreaks and numerous health hazards and the imminent risk of death. Much has been discussed about more efficient forms of control for this mosquito, considering that the chemical control, currently used, has been causing impacts on the environment and the health of the population. Thus, alternative methods have been evaluated. Among them, biological control through products formulated from Bacillus thuringiensis has stood out, as biotechnological advances have allowed to improve and enhance the products already on the market, as well as to develop new bioinsecticides from the entomopathogenic proteins produced by these microorganisms, aiming to make the larvae control more and more effective. To this end, this study aimed to carry out a bibliographic survey on the use of Bacillus thuringiensis as a form of biological control of Aedes aegypti larvae, due to the need to use safer and more effective methods of control for disease vector insects.

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