Pengaruh Penambahan Lisat pada Kultur Bacillus spp. terhadap Aktivitas Anti-Methicillin Resistant Staphylococcus aureus

Abstract

Optimasi kondisi kultur dari Bacillus spp. penghasil metabolit sekunder perlu dilakukan untuk meningkatkan produksi metabolit sekunder dan bioaktivitasnya. Penelitian ini bertujuan mengoptimasi produksi metabolit sekunder dari Bacillus spp. melalui penambahan lisat dari sel methicillin-resistant Staphylococcus aureus (MRSA) dan menentukan aktivitas antibakterinya terhadap MRSA. Tiga strain Bacillus spp., yaitu DJ4, DJ9, dan P1 masing-masing diremajakan pada media Nutrient Agar (NA), kemudian ditumbuhkan pada media Nutrient Broth (NB) sebagai media produksi metabolit sekunder. Metabolit sekunder bakteri diekstraksi menggunakan etil asetat. Penyiapan lisat dilakukan dengan metode heat-kill MRSA dilanjutkan dengan deteksi senyawa N-asetilglukosamin menggunakan High-Performance Liquid Chromatography (HPLC). Aktivitas anti-MRSA ketiga ekstrak ditentukan melalui uji Minimum Inhibitory Concentration (MIC) menggunakan metode microbroth-dilution. Hasil penelitian menunjukkan bahwa setelah dilakukan penambahan lisat, ketiga strain Bacillus spp. mampu menghasilkan metabolit sekunder dengan aktivitas anti-MRSA yang beragam. Peningkatan aktivitas anti-MRSA terjadi pada ekstrak strain DJ4 dari nilai MIC sebesar 25 µg/mL tanpa penambahan lisat menjadi 12,5 µg/mL setelah penambahan lisat. Ekstrak dari strain lainnya yakni DJ9 mengalami penurunan aktivitas anti-MRSA, sedangkan ekstrak strain P1 tidak terdapat pengaruh signifikan setelah penambahan lisat. Perbedaan respons ketiga strain Bacillus terhadap lisat mengindikasikan kemungkinan adanya variasi regulasi biosintesis antibiotik pada masing-masing strain.

Optimization of culture conditions of secondary metabolite-producing Bacillus spp. is necessary to increase secondary metabolite production and its bioactivity. This study aims to optimize secondary metabolite production from Bacillus spp. by adding lysates from methicillin-resistant Staphylococcus aureus cells (MRSA) and determine their antibacterial activity against MRSA. Three Bacillus strains—DJ4, DJ9, and P1—were cultured on Nutrient Agar media, then grown on Nutrient Broth media as a medium for secondary metabolite production. Bacterial secondary metabolites were extracted using ethyl acetate. MRSA lysate were prepared via the heat-kill method followed by detection of N-acetylglucosamine compounds using High-Performance Liquid Chromatography (HPLC). The anti-MRSA activity of each extract was determined by the minimum inhibitory concentration (MIC) using the microbroth-dilution method. The addition of lysate to bacterial cultures exhibited varying effects on the anti-MRSA activity of three Bacillus strains, as reflected in their differing minimum inhibitory concentration values. For the DJ4 strain, lysate supplementation enhanced anti-MRSA activity, with the MIC decreasing from 25 µg/mL to 12,5 µg/mL. In contrast, the DJ9 strain showed a reduction in anti-MRSA activity following lysate addition, while P1 strain displayed no significant change. These differential responses suggest strain-specific regulation of antibiotic biosynthesis, potentially influenced by the presence of lysate.