Propionicin PLG-1, Screening and Partial Characterization of the Protein

Propionibacterium thoenii P127 (propionicin PLG-1 producer strain) was screened for its antimicrobial activity against a wide range of microorganisms including, 14 Escherichia coli strains, 7 Propionibacterium strains, 3 yeast strains, 3 Lactococcus strains, 2 Lactobacillus strains, and one strain of each of Bacillus sp., Clostridium sp., Streptococcus sp., Oenococcus sp., and Aspergillus sp. The results indicated inhibition of above microbial strains with different degrees. Above findings were found to contradict the results obtained by other investigators. Therefore, total crude protein of the cell-free supernatant was partially purified using ammonium sulphate fractionation and retested again against above culture strains. The Results obtained indicated that total crude protein strongly inhibited the growth of all Escherichia coli and yeasts strains investigated. However, it moderate affected the growth of all propionibacteria strains expect Propionibacterium freudenreichii and weakly inhibited the growth of all lactic acid bacterial strains. However it showed negative effect on the growth of Aspergillus niger, Bacillus subtilis DB100 host, and Clostridium sporogenes DSM1446. Therefore, the total crude protein extract was exposed to SDS-PAGE and the band containing propionicin PLG-1 (~10 kDa) was extracted and retested against all culture strains investigated at the beginning and revealed similar data to the total crude protein extract.