Biodegradation of the Insecticide Bendiocarb by Bacillus thuringiensis in a Packed Biofilm Reactor

Carbamates are among the most commonly used xenobiotics as insecticides, even though these compounds are highly toxic to humans and animals. Within carbamates, bendiocarb has been used against a vast range of nuisance and disease vector insects and in agriculture on sugar beet and maize crops. Since 1999, the Environmental Protection Agency of the United States of America has banned bendiocarb use in the United States, although the World Health Organization continues to recommend it for the control of malaria in Africa. In Mexico, bendiocarb effectiveness for the control of disease vector insects transmitting dengue, Zika and chikungunya has been demonstrated. One of the remediation technologies to confront the problem of contamination by xenobiotic compounds is applying microorganisms that are able to use these compounds as substrates. In this context, the isolation of microorganisms capable of efficiently degrading bendiocarb is especially important. In this work, Bacillus thuringiensis was isolated from a microbial community isolated from soil samples collected of a composting plant at the northeast of Mexico City and tested for its ability to degrade bendiocarb. This bacterium immobilized in a biofilm reactor, using fragments of volcanic rock (tezontle) as a support and operated on a continuous basis, degraded more than 90% of the insecticide with high removal rates.