Electronic Theses and Dissertation

Infeksi Saluran Kemih (ISK) menjadi masalah kesehatan global dengan prevalensi tinggi dan disertai peningkatan resistensi antibiotik, sehingga mendorong pencarian sumber antibakteri alternatif termasuk dari bakteri endofit tanaman. Biji alpukat (Persea americana Mill.) berpotensi mengandung bakteri endofit penghasil senyawa antimikroba. Penelitian eksperimental ini bertujuan mengisolasi dan mengetahui aktivitas antibakteri cell-free supernatant (CFS) bakteri endofit biji alpukat terhadap Enterococcus faecalis, salah satu patogen ISK. Sebanyak enam isolat bakteri endofit (EP1-EP6) berhasil diisolasi dari biji alpukat melalui prosedur sterilisasi permukaan yang efektif, kemudian dikarakterisasi secara morfologi. CFS diperoleh dari kultur cair 72 jam yang disentrifugasi. Uji aktivitas antibakteri dilakukan dengan metode difusi cakram Kirby-Bauer menggunakan E. faecalis isolat klinis dengan empat kali pengulangan, kontrol positif ampisilin 10 µg, dan kontrol negatif media tryptic soy broth (TSB). Hasil penelitian menunjukkan bahwa seluruh isolat menghasilkan aktivitas antibakteri dengan kategori sedang berdasarkan klasifikasi Davis & Stout (1971), yaitu pada rentang 6,98–8,46 mm. Isolat EP3 memberikan diameter zona hambat tertinggi (8,46 ± 0,94 mm), diikuti oleh EP6 (8,16 ± 0,78 mm). Kontrol positif ampisilin menghasilkan zona hambat sangat kuat (26,62–27,85 mm), sedangkan kontrol negatif tidak menunjukkan adanya hambatan. Berdasarkan temuan ini disimpulkan bahwa CFS bakteri endofit biji alpukat mengandung metabolit sekunder yang mampu menghambat pertumbuhan E. faecalis, dengan isolat endofit Gram positif berbentuk bulat (EP3) dan Gram positif berbentuk batang yang membentuk spora (EP6) menunjukkan potensi tertinggi. Hasil penelitian ini dapat menjadi dasar pengembangan bakteri endofit sebagai sumber agen antibakteri alami untuk mengatasi tantangan resistensi antibiotik.

Kata Kunci: Bakteri Endofit; Biji Alpukat; Cell-free supernatant (CFS); Infeksi Saluran Kemih (ISK); Enterococcus faecalis; Antibakteri

Urinary Tract Infection (UTI) is a global health problem with high prevalence and increasing antibiotic resistance, prompting the search for alternative antibacterial sources including endophytic bacteria. Avocado seeds (Persea americana Mill.) potentially contain endophytic bacteria producing antimicrobial compounds. This experimental study aimed to isolate and determine the antibacterial activity of cell-free supernatant (CFS) from avocado seed endophytic bacteria against Enterococcus faecalis, one of the UTI pathogens. Six endophytic bacterial isolates (EP1-EP6) were successfully isolated from avocado seeds through effective surface sterilization procedure, then characterized morphologically. CFS was obtained from 72-hour liquid culture by centrifugation. Antibacterial activity was tested using Kirby-Bauer disk diffusion method against clinical E. faecalis isolate with four replications, positive control of ampicillin 10 µg, and negative control of tryptic soy broth (TSB) medium. Results showed that all isolates produced antibacterial activity in the moderate category according to Davis & Stout (1971) classification, within the range of 6.98–8.46 mm. Isolate EP3 gave the highest inhibition zone (8.46 ± 0.94 mm), followed by EP6 (8.16 ± 0.78 mm). Positive control (ampicillin) produced very strong inhibition zone (26.62–27.85 mm), while negative control showed no inhibition. Based on these findings, it is concluded that CFS from avocado seed endophytic bacteria contains secondary metabolites capable of inhibiting E. faecalis growth with Gram-positive round-shaped endophytic isolate (EP3) and Gram-positive rod-shaped spore-forming isolate (EP6) showing the highest potency. These results can serve as a basis for developing endophytic bacteria as a natural antibacterial agent source to address antibiotic resistance challenges. Keywords: Endophytic Bacteria; Avocado Seed; Cell-free supernatant (CFS); Urinary Tract Infection (UTI); Enterococcus faecalis; Antibacteria