Purification, characterisation and identification of acidocin LCHV, an antimicrobial peptide produced by Lactobacillus acidophilus n.v. Er 317/402 strain Narine

In the last two decades, antimicrobial peptides (AMPs) have been gaining attention as antimicrobial alternatives to chemical food preservatives and commonly used antibiotics. Lactobacillus acidophilus n.v. Er 317/402 strain Narine produces a small AMP with a molecular weight of 1.1 kDa, designated acidocin LCHV. In this study, the AMP was extremely heat stable (90 min at 130 °C), was active over a wide pH range and was found to be sensitive to proteolytic enzymes (trypsin, pepsin and proteinase K). Acidocin LCHV has a broad spectrum of activity both against Gram-positive and Gram-negative pathogens, including several that are classified as Especially Dangerous Infections by the World Health Organization as well as meticillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) was used to determine the molecular mass and sequence of the purified peptide. Complete killing with immediate impact on cells was observed within a very short period of time (10 min).