Novel Cytoplasmic Bacteriocin Compounds Derived from Selectively Kill , Including Methicillin-Resistant Staphylococcus aureus (MRSA).

(S. aureus) is one of the well-known agents causing atopic dermatitis (AD) in susceptible individuals, and () produces class I thermostable bacteriocins that can selectively kill , suggesting protective roles against AD. There is a large need for developing precise therapies only to target and not to harm the beneficial microbiome. On the agar well diffusion assay, live planktonic showed clear zones of inhibition of growth, but heat-killed cells and cell-free supernatants did not show this. These results would lead us to hypothesize that cytoplasmic bacteriocin from will be a promising agent to inhibit growth. Therefore, we have extracted a novel thermolabile cytoplasmic bacteriocin from using trichloroactic acid (TCA)/acetone precipitation method after cell lysis with a SDS-containing buffer. These bacteriocin selectively exhibited antimicrobial activity against and methicillin-resistance Staphylococcus aureus (MRSA), presenting no active actions against , , and . The extracted cytoplasmic bacteriocin compounds revealed several diffuse bands of approximately 40-70 kDa by SDS-PAGE. These findings suggest that these cytoplasmic bacteriocin compounds would be a great potential means for growth inhibition and topical AD treatment.