Isolation and characterization of a highly hydrophobic new bacteriocin (gassericin A) from Lactobacillus gasseri LA39

A new bacteriocin, gassericin A, was purified from the culture fluid of Lactobacillus gasseri LA39 mainly by reverse-phase (RP) chromatography. The purification of gassericin A from a modified MRS broth, in which Tween 80 had been replaced by oleic acid, resulted in a 4500-fold increase in specific activity with a 6% recovery. Gassericin A was eluted as a single peak on the chromatogram from RP-HPLC and migrated by SDS-PAGE as a single band with a molecular weight of ca. 3.8 kDa. Gassericin A, a highly hydrophobic bacteriocin, was slightly soluble in water, but its solubility was increased by adding alcohol and acetonitrile. An amino acid analysis revealed that it was composed of 45.7% hydrophobic amino acids in the total residues of 35 amino acids. Gassericin A produced in the MRS broth associated strongly with Tween 80, although several further trials of dissociation were unsuccessful.