Methanol extract of Black soldier fly (<i>Hermetia illucens</i>) prepupae against <i>Aeromonas</i> and <i>Staphylococcus</i> aureus bacteria <i>in vitro</i> and in <i>silico</i>

Abstract

Background: Staphylococcus and Aeromonas bacteria are pathogens in humans and animals. The therapy disrupts the virulence structure of the bacteria, resulting in bacterial death. Currently, chemical drugs have resulted in many resistant bacteria, so it is necessary to find alternative natural materials that are not toxic and do not quickly induce resistance.
Aims: This study aimed to analyze the potential of methanol extract from Black soldier fly (BSF) prepupae as an antibacterial agent against Staphylococcus aureus and Aeromonas through in silico and in vitro tests.
Methods: The BSF prepupae methanol extract was analyzed for protein and fatty acid contents. Disc diffusion method, minimal inhibitory concentration, and minimum bactericidal concentration test were used for in vitro tests against Staphylococcis and Aeromonas. Molecular docking of the active ingredients (defensin, chitin, and chitosan as well as fatty acids) in BSF was downloaded from the NCBI database and docked by the Hex Cuda version 8.0 program with Correlation type parameters Shape + Electro and Grid Dimension version 0.6. Docking results were analyzed using the Discovery Studio program version 21.1.1.
Results: The highest fatty acid contents in the extract were palmitic acid and myristic acid. Methanol extract from BSF prepupae acted as a bactericidal agent against S. aureus at a concentration of 320 mg/ml, in contrast to Aeromonas, which still showed bacterial growth. The results of the in silico test showed that defensin–aerolysin and defensin–hemolysin was bound to the same active site area. However, the amount of binding energy produced by 69-Defensin-
83-aerolysin was higher than all defensin types in BSF against Aeromonas. Chitin and chitosan showed a bond on the active site of aerolysin and hemolysin, but chitosan had a stronger bond than chitin. In silico study also showed the strongest binding affinity of BSF fatty acids to isoleucyl-tRNA synthetase of S. aureus.
Conclusion: The study showed that methanol extract from BSF prepupae had potential capability as an antibacterial agent against S. aureus than Aeromonas in vitro and in silico.