Partial Purification and Characterization of Bacteriocins from Lactobacillus plantarum SB7 and Bacillus amyloliquefaciens BC9 Isolated from Fermented Sumbawa Mare's Milk as Food Preservative Candidates

摘要

Bacteriocins are protein substances originated from prokaryote organism that has antibacterial activity. This study was aimed to partially purify and characterize the bacteriocins produced by Lactobacillus plantarum SB7 and Bacillus amyloliquefaciens BC9 isolated from fermented Sumbawa mare's milk. The pH-neutralized cell-free supernatant of Lactobacillus plantarum SB7 and Bacillus amyloliquefaciens BC9 was subjected to ammonium sulfate precipitation, and then further purified by dialyzing (cut-off 5 kDa). The protein concentration was measured using Bradford method. The molecular weight of the bacteriocins was determined by SDS-PAGE. The antibacterial activity of protein bands was confirmed by soft-agar overlay method. The concentration of partially purified bacteriocins of Lb. plantarum SB7 and B. amyloliquefaciens BC9 was 12.56 μg/μL and 15.21 μg/μL, respectively. A high recovery bacteriocin purification has been indicated through the inhibition zone diameter. Molecular weight size of partially purified bacteriocins of Lb. plantarum SB7 was ±48 and 17 kDa, and B. amyloliquefaciens BC9 was ±48 kDa. This was consistent with the presence of antibacterial activity from the polyacrylamide gel slice of Lb. plantarum SB7 against the indicator of bacteria. Meanwhile, the antibacterial activity of B. amyloliquefaciens BC9 was not confirmed might be due to its sensitivity to SDS content.