[Antibacterial activity verification of insecticidal peptide U10-MYRTX-Mri1a and activity evaluation of its...

After China implemented the policy of banning the application of antibiotics in feed and reducing the application of antibiotics in animal production, there has been an urgent need to develop new antibiotic alternatives. In this context, animal venom peptides are considered highly promising alternatives to antibiotics because they possess multifunctional properties and appear to employ the same membrane-targeting mechanism for both insecticidal and bactericidal activities. This study examines the antibacterial activity of U10-MYRTX-Mri1a, an insecticidal peptide derived from the venom of European red ants (Manica rubida), and assesses the functionality of its recombinant fusion protein produced in Pichia pastoris, thereby providing experimental support for the development of antibiotic alternatives. According to the concept of structural similarity-functional crossover, we evaluated the antibacterial activities of the insecticidal peptide U10-MYRTX-Mri1a derived from Myrmica rubra against Escherichia coli O157:H7 and Staphylococcus aureus ATCC 25923. U10-MYRTX-Mri1a was chemically synthesized. Its minimum inhibitory concentrations (MIC) were 16 µmol/L for E. coli O157:H7 and 8 µmol/L for S. aureus ATCC 25923, and the minimum bactericidal concentrations for both strains were 16 µmol/L. Scanning electron microscopy showed that the peptide treatment caused collapse of the bacterial membrane structure and cell fragmentation. Meanwhile, the fusion peptide U10-MYRTX-Mri1a-GNA was expressed via the constitutive promoter glyceraldehyde-3-phosphate dehydrogenase (GAP) in Pichia pastoris X33. The fusion peptide inhibited E. coli O157:H7 and S. aureus ATCC 25923 by (89.37±2.22)% and (88.27±2.81)%, respectively. The findings indicate that the insecticidal peptide U10-MYRTX-Mri1a exhibits promising potential as a natural antibiotic substitute, thereby broadening the spectrum of available antibiotic-alternative agents. Furthermore, a reliable biosynthesis platform using Pichia pastoris was successfully developed, which lays a solid groundwork for future research and development of antibiotic alternatives.