Bt Research 2024, Vol.15, No.5, 248-256 http://microbescipublisher.com/index.php/bt 249 formulations typically involve the use of carriers and adjuvants to stabilize the active ingredients and enhance their efficacy. For instance, spray drying is a widely used technique to produce dry formulations, which involves converting a liquid mixture into a dry powder by rapidly drying with a hot gas. This method is advantageous for its cost-effectiveness and ability to produce stable products with long shelf lives (Figure 1) (Shi et al., 2020; Assadpour and Jafari, 2019). The use of dual microbial agents, such as combining Bacillus thuringiensis (Bt) with Beauveria bassiana, has shown synergistic effects, enhancing the overall pest control efficacy when formulated as a dry powder. Figure 1 (a) A common mini-spray dryer and (b) a schematic representation of the spray-drying process, along with different food bioactive ingredients and relevant wall materials for the spray-drying encapsulation process, supplemented with a list of investigated spray-drying conditions and important analyses on final encapsulated powders (Adopted from Assadpour and Jafari, 2019) 2.2 Liquid formulations Liquid formulations are another prevalent form of Bt-based biopesticides. These formulations are typically produced through fermentation processes and can be applied directly to crops. Liquid fermentation techniques have been developed to produce high concentrations of Bt spores and crystals, which are then mixed with other microbial agents to improve efficacy (Sayed and Behle, 2017). However, liquid formulations often face challenges related to stability and shelf life, as the active ingredients can degrade over time due to environmental factors such as temperature and light (Hernandez-Tenorio et al., 2022). To address these issues, encapsulation techniques are often employed to protect the active ingredients and extend the shelf life of the formulations. 2.3 Encapsulation techniques Encapsulation techniques have gained significant attention in the formulation of Bt-based biopesticides due to their ability to protect the active ingredients from environmental degradation and control the release rate. Various
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