Rapid method for extracting the antibiotic mutacin 1140 from complex fermentation medium yeast extract.

The peptide antibiotic mutacin 1140 belongs to the group of antibiotics called lantibiotics. They are ribosomally synthesized and undergo extensive enzymatic modifications before being excreted into the culture medium. By using reverse-phase-high-performance liquid chromatography (RP-HPLC) and a semiquantitative bacteriocin bioassay to track mutacin 1140, an efficient ammonium sulfate (AS) precipitation method has been developed for removing mutacin 1140 from a complex medium containing 5% yeast extract. This method minimizes the amounts of fermentation by-products and media components that make downstream purification processes more difficult and economically infeasible. The method may be adaptable for the initial purification step of other lantibiotics. A threefold decrease in the precipitation of the medium components found in yeast extract, at pH 8.0 vs. pH 2.0, may have broad utility for the isolation of secondary metabolites produced in this complex medium. The average yield of mutacin 1140 from the fermentation medium was determined as 66%.