Production of Bacillus thuringiensis var. Israelensis Toxin Using Agro-Industrial Waste-Based Media for Mosquito Larvicide

Abstract

Dengue has been prevalent in Malaysia for decades and eradication measures remain purely ineffective. The use of chemical-based insecticide for control measures is considerably non-sustainable and hence the use of more environmental options such as biological larvicide is preferable. One of the biological larvicides that has proven to be very effective against Dengue vectors like Aedes mosquitoes is a toxin produced by Bacillus thuringiensis var. israelensis (Bti). The toxin produced by this strain targets and kills only the larvae of Aedes sp. mosquitoes, leaving other ecological and aquatic organisms alive; making Bti toxin the most environmentally friendly biopesticide for mosquito control. Though, Bti-based products are marketed at a high and premium price due to the cost of importation, transportation and production. This is unacceptable from a long-term control perspective as Malaysia needs to have a lower-price alternative for such biotechnological products to be used by local consumers. This study aimed to evaluate various cheaper alternative media, in particular from local agricultural biomass wastes or residues, that could support the production of Bti toxin. In this study, we found that unused coconut water obtained from the coconut milk industry was not only able to promote sporulation and toxin production but also able to retain the toxin efficacy of larvicide activity as compared to conventional nutrient broth medium. Collectively, outputs from this study permit further refinement of media replacement models and cost-saving formulations towards industrializing the prototypes.