Characterization of Mexican Bacillus thuringiensis strains toxic for lepidopteran and coleopteran larvae.
Bacillus thuringiensis strains C-4, C-9, GM-7, and GM-10, isolated from northeast Mexico and selected for their high toxicity against lepidopteran and coleopteran pests, were characterized following United States Environmental Protection Agency (EPA)'s guidelines. Flagellar serotyping revealed that GM-7 and GM-10 belonged to serotype aizawai, whereas C-4, C-9 corresponded to the kumamotoensis serotype. GM-10 and C-9 were also shown to be the most effective against lepidoptera and coleoptera larvae, respectively. None of the tested strains produced beta-exotoxin or showed activity against mosquitoes. GM-7 and GM-10 were sensitive to R-41 and CP-51 phages. All strains synthesized crystal proteins of 130-140 kDa. PCR analysis showed that C-4, GM-7, and GM-10 strains expressed cry1 genes, and C-9 expressed cry3 and cry7/8 genes, but not cry1. However, the C-9 strain had no cross-reaction with antisera raised against Cry3A and Cry7A proteins. GM-7 and GM-10 were sensitive to R-41 and CP-51 phages. When the delta-endotoxin (crystal) from the four strains was subcutaneously injected to Balb/c mice, alone or in combination with spores, only C-4 and C-9 provoked tissue necrosis similar to that caused by the beta-exotoxin producer HD-41. Tissue necrosis was prevented with the injection of pentoxifylline, an inhibitor of tumor necrosis factor alpha (TNF-alpha) production, suggesting a role of this cytokine in the observed effect. Our results demonstrated that GM-7 and GM-10 strains are effective and suitable for control of lepidopteran pests and safe for mammals under EPA regulations. The potential of the C-9 strain for the control of several coleopteran pests, and the induction of tissue necrosis in mice by C-4 and C-9 strains, are discussed.
Tamez-Guerra
Patricia
P
Departamento de Microbiología e Inmunología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León (UANL), A. P. 46-F, 66451 San Nicolás de los Garza, N. L., Mexico. patamez@uanl.mx
Iracheta
Maria M
MM
Pereyra-Alférez
Benito
B
Galán-Wong
Luis J
LJ
Gomez-Flores
Ricardo
R
Tamez-Guerra
Reyes S
RS
Rodríguez-Padilla
Cristina
C
D000241:Adenosine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D000818:Animals; D016863:Bacillaceae Infections / Q000473:pathology; D001413:Bacillus thuringiensis / Q000145:classification / Q000502:physiology*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000633:toxicity; D001427:Bacterial Toxins; D015153:Blotting, Western; D001517:Coleoptera / Q000469:parasitology*; D004731:Endotoxins / Q000235:genetics / Q000633:toxicity; D005260:Female; D006460:Hemolysin Proteins; D007814:Larva / Q000469:parasitology*; D007915:Lepidoptera / Q000469:parasitology*; D051379:Mice; D010572:Pest Control, Biological / Q000379:methods*; D016133:Polymerase Chain Reaction; D012703:Serotyping; D012867:Skin / Q000187:drug effects / Q000473:pathology; D013400:Sugar Acids
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D013400:Sugar Acids; C030956:insecticidal crystal protein, Bacillus Thuringiensis; C068295:thuringiensin; D000241:Adenosine