The influence of different amounts of Escherichia coli inducement on the antibacterial activity of Periplaneta Americana hemolymph against common nosocomial pathogens

Insects, such as P. americana, have the capability to produce antimicrobial proteins (AMPs) that play as an effector substance in the innate immunity of vertebrates and invertebrates. However, there were no studies yet on the influence of different amounts of E. coli inducement on the variability of its antibacterial activity that would be relevant for the selection of representative hemolymph in this growing discovery of research. Five groups of P. americana were induced with 50 L, 75 L, 100 L, 125 L, 150 L of E. coli and crude hemolymph extracts were collected 6-12 hours post inducement. The variability of hemolymphs’ antibacterial activity was tested against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853. The protein content and molecular weight of the AMPs were determined through Bradford Assay and native SDS-PAGE. Comparative results of the antibacterial activity showed significant p-value of 0.049 in hemolymph from 150 L induced P. americana against S. aureus ATCC 25923 with its molecular weight of 75kDa while 75 L induced hemolymph provided the significant p- value of 0.024 against E. coli ATCC 25922 correlating its protein content of 2212.77 g/mL. However, the hemolymph is not effective against P. aeruginosa since the values obtained were close to negative control. The resulting effective antibacterial activity of the hemolymph has an advantage when induced 6-12hours at the highest tolerable amount of E. coli as the inducible biologic material, presence of increased amounts of active AMPs while considering the strain it acts upon.

Keywords: Escherichia coli inducement, antimicrobial proteins, hemolymph, Periplaneta americana