Isolation of <i>Bacillus zhangzhouensis</i> OBB Liu et al. (Caryophanales: Bacillaceae) from native <i>Polyphylla fullo</i> (L., 1758) (Coleoptera: Scarabaeidae) larvae, PCR-based detection of <i>cry1</i> gene and evaluation of its biological control potential

Bacillus zhangzhouensis OBB Liu et al. (Caryophanales: Bacillaceae) isolate was obtained from Polyphylla fullo (L., 1758) (Coleoptera: Scarabaeidae) larvae in the Microbiology Laboratory of the Biology Department of the Faculty of Science of Atat & uuml;rk University in 2024. Additionally, the presence of the cry1 gene was identified. After endospore staining of the isolate, the presence of crystal protein was detected by phase contrast microscopy and SEM analysis. As a result of PCR, only the presence of the cry1 gene was detected and confirmed. The total protein contents were compared with those of Bacillus thuringiensis (Berliner, 1915) (Bacteria: Bacillaceae) by performing SDS-PAGE analysis using a crystal protein and spore mixture. B. zhangzhouensis OBB showed bands similar to 250 kDa and similar to 80 kDa, while B. thuringiensis showed bands corresponding to similar to 70 kDa and similar to 45 kDa. Probit analysis was used to determine the LC50 value of the isolates, and the Abbott method was used to determine the mortality percentages of the larvae. Spore-crystal mixtures of B. thuringiensis and B. zhangzhouensis OBB isolates were tested against P. fullo larvae at doses of 1000, 2000, and 4000 ppm. The highest mortality rate was determined in the spore-crystal mixture of B. zhangzhouensis OBB isolate at 4000 ppm dose.