A novel antibacterial peptide active against peach crown gall (Agrobacterium tumefaciens) isolated from cyanide-tolerant actinomycetes G19.

An antimicrobial peptide was extracted from the antagonistic actinomycetes G19. It was designated as G19-F. By using MALDI-TOF mass spectrometry, the molecular weight of G19-F was determined. The primary structure of the antimicrobial peptide was determined using N-terminal sequencing and mass spectrometry. Results showed that the peptide had eleven amino acids, with the sequence D-V-C-D-G-G-D-G-D-E-D, and a calculated molecular mass of 1,096 Da. G19-F showed antimicrobial activity against peach crown gall caused by Agrobacterium tumefaciens. The antimicrobial peptide maintained its activity after being heated to 100 °C and exhibited stability from pH 4 to 10. Its activity has also remained after ultraviolet irradiation. The mechanism by which G19-F inhibits A. tumefaciens was to increase permeability of the cell membrane and destroy the cell wall structure. Furthermore, as a novel peptide, it has a potential for cure A. tumefaciens infection.