Isolation and Characterization of a Novel Antibacterial Protein From Moringa oleifera Seeds

Moringa oleifera is an edible and medicinal plant cultivated worldwide. Its seeds are rich in proteins, oil, and glucosinolates. Previous studies reported the antibacterial properties of Moringa proteins, but the specific protein responsible remains unidentified. This study was aimed at isolating and characterizing an antibacterial protein in M. oleifera seeds. A silica gel column chromatographic separation method combined with a silica gel thin-layer chromatographic detection and purification procedure was developed to isolate Moringa antibacterial protein, and its antibacterial activity, molecular weight, and protein type were determined. The results indicated that when the amount of protein sample was 1.0 mg, protein extracted from M. oleifera seeds presented antibacterial activity, with inhibition zones of 13.0 ± 0.2 mm (Staphylococcus aureus ATCC 29213), 12.0 ± 0.0 mm (Staphylococcus aureus ATCC 25923), 14.0 ± 0.3 mm (Clostridium perfringens CVCC 2030), 12.0 ± 0.1 mm (Streptococcus CVCC 3307), 16.0 ± 0.2 mm (Actinobacillus CVCC 3589), 13.0 ± 0.4 mm (Salmonella CVCC 79301), and 15.0 ± 0.3 mm (Salmonella CVCC 503), but no antibacterial activity toward Escherichia coli CVCC192 was observed. The Moringa antibacterial protein was identified as a 2S albumin with a molecular weight of approximately 20 kDa after LC–MS determination and comparison with the NCBI protein database. This study successfully isolated and identified 2S albumin as the active antibacterial protein in M. oleifera seeds. These findings provide valuable ideas and methods for the potential application of the Moringa antibacterial protein in the food preservation and pharmaceutical industries.