Obtaining and determination of the concentration in the culture fluid of phaecin – peptide bacteriocin Enterococcus faecium

Phaecin, a peptide bacteriocin with a molecular mass of ~5 kDa, was obtained and purified to an electrophoretically pure state with a yield of ~70% of the total activity in the culture fluid. The method of time-of-flight mass spectrometry (MALDI) showed that bacteriocin consists of two components A and B with similar molecular mass. In previously published works, the yield of purified bacteriocins, usually did not exceed 4–5% of the total activity in the culture fluid. The authors believe that the increase in yield is due to the fact that not only the similarity of bacteriocins with high molecular mass proteins was taken into account, but also differences associated with low molecular mass, the ability to hydrophobic interaction at slightly alkaline pH values and resistance to denaturation. Using the Scopes method, it was possible to determine the concentration of phaecin in the final stage of purification and in the culture fluid in absolute units (mg/l). The methods of the purification with high yield described in this work are probably applicable to other bacteriocins due to the proximity of their physicochemical properties. Key words: Enterococcus faecium, Listeria monocytogenes, bacteriocin, phaecin, culture liquid, adsorption chromatography, Scopes equation