Molecular characteri̇zati̇on of chi̇ti̇nase protei̇ns of serratia ficaria bacteri̇a i̇solated from pieris brassicae and determi̇nati̇on of thei̇r vi̇rulence effects

Cabbage, one of the vegetables belonging to the Brassicae family, is very important in terms of both its health values and economic value. Today, a search for new alternative solutions to chemicals has emerged to control Pieris brassica, which is its main pest. Serratia ficaria is a potential bioinsecticide agent due to the presence of chitinase A, chitinase B and chitinase D genes in the genome, which cause the destruction of insect exoskeletons and intestinal epithelial tissue. It was observed that Pieris brassicae larvae collected from cabbage cultivated fields in Erzurum province suddenly died en masse. Next-generation sequencing of the 16S rRNA gene was performed to understand the cause of infection. As a result of the analysis, it was understood that the cause of the infection was S. ficaria bacteria. In this thesis study, the chitinase genes of the local and effective S. ficaria entomopathogenic isolate were amplified by the Gibson cloning method, and the production and purification of Chitinase A, B and D enzymes were carried out. Then, chitinase enzymes were applied to P. brassicae larvae by droplet feeding method and the larvae were infected. Mortality rates were determined as 100%, 82% and 90%, respectively. It has been found that the most effective enzyme is Chitinase A. As a result of the dose trial with Chitinase A enzyme, the LD50 value was determined as 1095.31 ng/μl and the LT50 value was 2.17 days. As a result, it was determined that the chitinase enzyme of S. ficaria is an effective potential bioinsecticide that can be used in the fight against P. brassicae.