Isolation and Antibacterial Activity of Bacteriocins from Lactic Acid Bacteria Isolated from Red Cabbage Sauerkraut (Brassica oleracea L.) against Escherichia coli and Staphylococcus aureus / Isolasi dan Uji Antibakteri Bakteriosin Bakteri Asam Laktat (BAL) dari Sauerkraut Kubis Ungu (Brassica oleracea L) Terhadap Escherichia coli dan Stapylococcus aureus

Background: Red cabbage sauerkraut (Brassica oleracea L.) is a fermented vegetable matrix that supports the growth of lactic acid bacteria (LAB), some of which produce bacteriocins with potential as natural food biopreservatives. Objective: This study aimed to isolate and phenotypically characterize LAB from red cabbage sauerkraut and evaluate the antibacterial activity and physicochemical stability of the partially purified bacteriocin against Staphylococcus aureus and Escherichia coli. Methods: LAB were isolated on MRS agar, characterized by colony and cell morphology, Gram staining, catalase activity, and motility, and screened for antibacterial activity. Bacteriocin from the selected isolate was partially purified by ammonium sulfate precipitation and dialysis. Stability was evaluated across pH 2–11, temperatures of 30–121 °C, pepsin exposure, Tween 20 and Tween 80, and UV-C irradiation. Antibacterial activity was assessed by agar diffusion. Results: Three presumptive LAB isolates (BAL1, BAL2, and BAL3) were obtained, with BAL1 showing the greatest antibacterial activity. Untreated bacteriocin produced inhibition zones of 11.2 mm against S. aureus and 12.8 mm against E. coli. Activity was retained most strongly at pH 3–5 and 30–40 °C, decreased after pepsin and UV-C exposure, and increased in the presence of Tween 20 or Tween 80. Conclusion: BAL1 from red cabbage sauerkraut produces a proteinaceous antibacterial substance with stability under acidic and moderate-temperature conditions, supporting its further characterization as a candidate food biopreservative.

Latar Belakang: Sauerkraut kubis ungu (Brassica oleracea L.) merupakan matriks sayuran fermentasi yang mendukung pertumbuhan bakteri asam laktat (BAL), termasuk isolat yang berpotensi menghasilkan bakteriosin sebagai biopreservatif pangan alami. Tujuan: Penelitian ini bertujuan mengisolasi dan mengarakterisasi secara fenotipik BAL dari sauerkraut kubis ungu serta mengevaluasi aktivitas antibakteri dan kestabilan fisikokimia bakteriosin yang dimurnikan secara parsial terhadap Staphylococcus aureus dan Escherichia coli. Metode: BAL diisolasi pada media MRS agar dan dikarakterisasi berdasarkan morfologi koloni dan sel, pewarnaan Gram, uji katalase, serta motilitas. Bakteriosin dari isolat terpilih dimurnikan secara parsial melalui presipitasi amonium sulfat dan dialisis. Kestabilannya dievaluasi pada pH 2–11, suhu 30–121 °C, paparan pepsin, Tween 20 dan Tween 80, serta iradiasi UV-C. Aktivitas antibakteri ditentukan dengan metode difusi agar. Hasil: Diperoleh tiga isolat BAL presumtif, yaitu BAL1, BAL2, dan BAL3, dengan BAL1 menunjukkan aktivitas antibakteri terbesar. Bakteriosin tanpa perlakuan menghasilkan zona hambat 11,2 mm terhadap S. aureus dan 12,8 mm terhadap E. coli. Aktivitas paling baik dipertahankan pada pH 3–5 dan suhu 30–40 °C, menurun setelah paparan pepsin dan UV-C, serta meningkat setelah penambahan Tween 20 atau Tween 80. Kesimpulan: BAL1 dari sauerkraut kubis ungu menghasilkan senyawa antibakteri bersifat protein yang relatif stabil pada kondisi asam dan suhu sedang sehingga layak dikarakterisasi lebih lanjut sebagai kandidat biopreservatif pangan.