Purification of Bioactive Peptide with Antimicrobial Properties Produced by Saccharomyces cerevisiae .

A variety of organisms produce bioactive peptides that express inhibition activity against other organisms. Saccharomyces cerevisiae is considered the best example of a unicellular organism that is useful for studying peptide production. In this study, an antibacterial peptide was produced and isolated from Saccharomyces cerevisiae (Baker's yeast) by an ultrafiltration process (two membranes with cut-offs of 2 and 10 kDa) and purified using the aKTA Pure 25 system. Antibacterial peptide activity was characterized and examined against four bacterial strains including Gram-positive and Gram-negative bacteria. The optimum condition for yeast growth and antibacterial peptide production against both Escherichia. coli and Klebsiella aerogenes was 25-30 degrees C within a 48 h period. The isolated peptide had a molecular weight of 9770 Da, was thermostable at 50-90 degrees C for 30 min, and tolerated a pH range of 5-7 at 4 degrees C and 25 degrees C during the first 24 h, making this isolated antibacterial peptides suitable for use in sterilization and thermal processes, which are very important aspect in food production. The isolated antibacterial peptide caused a rapid and steady decline in the number of viable cells from 2 to 2.3 log units of gram-negative strains and from 1.5 to 1.8 log units of gram-positive strains during 24 h of incubation. The isolated antibacterial peptide from Saccharomyces cerevisiae may present a potential biopreservative compound in the food industry exhibiting inhibition activity against gram-negative and gram-positive bacteria.