Effects of physicochemical interactions and microbial activity on the persistence of Cry1Aa Bt (Bacillus thuringiensis) toxin in soil

► Insecticidal protein Cry1Aa persists in soil for up to 4 months. ► Detectable levels initially decrease rapidly then more slowly. ► There was no evidence that the decline was driven by microbial activity. ► Protein interaction with soil surfaces or conformation may evolve with time.