Isolation and distribution of mosquito-larvicidal cry genes in Bacillus thuringiensis strains native to Saudi Arabia.
Trop Biomed
; 31(4): 616-32, 2014 Dec.
Article
em En
| MEDLINE
| ID: mdl-25776587
ABSTRACT
A total of 157 environmental samples were collected from 11 ecological regions across Saudi Arabia to isolate native Bacillus thuringiensis (Bt) strains. Bt isolates (n=103) were recovered by the 50% (v/v) ethanol treatment method with Bt index range of 0.01 to 0.4. Most of Bt isolates showed spherical crystals (54%), while, irregular, bi-pyramidal, and spore-attached crystal constituted 27, 16 and 3% respectively. PCR analysis with eight general and specific dipteran primers of Cry and Cyt genes, revealed positive amplification for cry4 & cyt1, and cry4A, cry4B and cyt2, and cry 10 and cry 11 genes in 28%, 26%, 22%, and 25% of tested strains respectively; whereas cry2 gene was not detected except with the reference Bt kurstaki HD-1 strain. Bioassays against Aedes caspuis and Culex pipiens larvae indicated that 11 strains displayed better larvicidal activity compared with Bacillus thuringiensis H14 (Bti) reference (LC50 0.6 µg/ml) strain against Ae. caspuis, but only two strains (620A & 633R1, LC50 of 0.09 µg/ml & 0.064 µg/ml) that gave significant enhancement. Additionally, one strain (633R1) showed LC50 similar to that of Bti H14 (LC50 0.064 µg/ml) against Cx. pipiens. With the exception of cyt primers, sequenced DNA of all positive primers amplicons revealed 95 to 99% identity in GenBank with Bacillus thuringiensis subsp. israelensis plasmid pBtoxis and also correlated with its SDS-PAGE expressed protein profiles analysis. It is hoped that our wild bio-insecticide Bt strains can be explored in future in the control of mosquito-vector borne diseases in Saudi Arabia.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bacillus thuringiensis
/
Proteínas de Bactérias
/
Aedes
/
Culex
/
Endotoxinas
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Microbiologia Ambiental
/
Proteínas Hemolisinas
/
Inseticidas
Limite:
Animals
País/Região como assunto:
Asia
Idioma:
En
Revista:
Trop Biomed
Assunto da revista:
MEDICINA TROPICAL
/
PARASITOLOGIA
Ano de publicação:
2014
Tipo de documento:
Article