Induction of antimicrobial peptides from Bacillus thuringiensis challenged Spodoptera litura larvae and investigation of the antimicrobial properties of hemolymph samples

Abstract

Antimicrobial peptides constitute key factors in insect humoral immune response against invading microorganisms. In this study, biochemical approach was identified antimicrobial peptides which appeared in larval hemolymph of Spodoptera litura after bacterial challenge. HPLC profile showed two major peaks in two samples, Brassica oleracea and Ricinus communis fed S. litura that were collected at 5 min interval. It was shown to be active against Gram-positive and Gram-negative bacteria. The highest zone of inhibition was observed in Staphylococcus aureus and Escherichia coli in B. oleracea fed S. litura hemolymph fraction II and R. communis fed S. litura hemolymph fraction I and it also contributes the increased antioxidant, lysozyme, and less hemolytic activity were increase in treated groups. TLC activity was tested with hemolymph extract samples, pink color pots was identified the protein present in the samples. An SDS-PAGE result shows that high expression of antimicrobial peptide present in the treated sample. The appearance of peptides with such different properties in insect hemolymph in response to immune challenge indicates the complexity of the insect immune system.