Producción de delta endotoxina y enzimas hidrolíticas en dos medios de cultivo utilizando Bacillus thuringiensis RT para el control de Spodoptera frugiperda

CARRIZO, ALFONSO EMANUEL; LOTO, FLAVIA; MENTEL, ISABEL; PERA, LICIA MARÍA; BAIGORÍ, MARIO DOMINGO

Tucumán

Congreso; XXIX Jornadas Científicas; 2012

Asociación de Biología de Tucumán.

Biopesticides prepared from Bacillus thuringiensis (Bt) are an option for pest control for agriculture, forestry and public health. This microorganism produces delta-endotoxin and hydrolytic enzymes that increase its pathogenicity to target insects and could be exploited industraly. The aim of this work was to evaluate the production of delta-endotoxin and hydrolytic enzymes from Bt RT in two culture media. The native isolate Bt RT was grown in both LB and M5 medium (formulated from agro-industrial wastes) using an fermenter with a working volume of 3L. Delta-endotoxin production was tested by the solubilization in alkaline condition method. Proteins were measured by Bradford assay. Hydrolytic activities were evaluated using the agar diffusion method. Plates containing different substrates in 1.5 % agar were incubated for 24 h at 30 °C. Hydrolysis halos were developed with iodine vapors. The product obtained in both media was tested against Spodoptera frugiperda larvae on artificial diet and maize seedlings. After 5 days of cultivation, a concentration of delta-endotoxin of 155.67 and 664.32 mg/L were observed in LB and M5, respectively. Concerning the hydrolytic activities the following radius (mm) were measured: amylase (LB: 0, M5: 2.2), carboxymethylcellulose (LB: 0.5, M5: 8.0), protease (LB: 1.1, M5: 5.3), chitinase (LB: 0.5, M5: 8.9) and xylanase (BL: 0, M5: 6.2). No activity was detected for both lipase and pectinase. The effectiveness of the formulation was 100% for M5 using both diet and seedlings, while effectiveness with LB was 61.40% and 58.33%, respectively. Proyect supported by PIP 297 and CIUNT 26/D409.