Formulation-dependent sugar regulation enhances biofilm-mediated stability and bioactivity of Bacillus thuringiensis formulations.

Sugars are important carbon sources involved in microbial growth and functional regulation. However, how sugars with different structural characteristics regulate microbial pesticide performance in complex formulation systems remains unclear. In this study, Bacillus thuringiensis (Bt) formulations were used to systematically evaluate the effects of different sugars on functional traits. The results showed pronounced type-dependent regulatory effects. Sugars with distinct structural features modulated biofilm formation by affecting cell adhesion and extracellular polysaccharide production. An optimized sugar combination increased biofilm yield by approximately tenfold. Certain sugars further enhanced UV tolerance and insecticidal activity. For example, pectin increased the survival rate of suspension concentrates by 5.3-fold after 4 h of UV exposure, while glucose, glycerol, and maltose improved insecticidal activity by 2.72-3.91-fold. Further analysis indicated that sugar structural characteristics are critical determinants of their regulatory effects, influencing bacterial surface interactions and the microenvironment. This biofilm-centered mechanism showed consistency across different formulation types. Overall, this study provides new insights into the development of stable and efficient Bt-based biopesticides.