Antibacterial peptide PMAP-37(F34-R), expressed in Pichia pastoris, is effective against pathogenic bacteria and preserves plums

Background: Recently, researchers have focused on the search for alternatives to conventional antibiotics. Antimicrobial peptides are small bioactive peptides that regulate immune activation and have antibacterial activity with a reduced risk of bacterial resistance. Porcine myeloid antibacterial peptide 37 (PMAP-37) is a small-molecule peptide with broad-spectrum antibacterial activity isolated from pig bone marrow, and PMAP-37(F34-R) is its analogue. In this study, PMAP-37(F34-R) was recombinantly expressed in Pichia pastoris , and the recombinant peptide was further investigated for its antibacterial properties, mechanism and preservative in plums. Results: To obtain a Pichia pastoris strain expressing PMAP-37(F34-R), we constructed a plasmid expressing recombinant PMAP-37(F34-R) (pPICZα-PMAP-37(F34-R)-A) and introduced it into Pichia pastoris . Finally, we obtained a highly active recombinant peptide, PMAP-37(F34-R), which inhibited the activity of both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration is 0.12–0.24 µg/mL, and it can destroy the integrity of the cell membrane, leading to cell lysis. It has good stability and is not easily affected by the external environment. Moreover, hemolysis experiments showed that PMAP-37(F34-R) had a low hemolytic ability against mammalian cells. Additionally, PMAP-37(F34-R) showed a good preservative effect in plums. The decay and weight loss rates of the treated samples were significantly lower than those of the control group, and the respiratory intensity of the fruit was delayed in the experimental group. Conclusions: In this study, we constructed a recombinant Pichia pastoris strain, which is a promising candidate for extending the shelf life of fruits and has potential applications in the development of new preservatives.