Electronic Theses and Dissertation

Ikan naleh (Barbonymus sp.) merupakan jenis ikan air tawar endemik yang hidup di sungai di wilayah Barat Aceh terutama Kabupaten Nagan Raya. Penelitian ini bertujuan untuk mengetahui karakteristik dan aktivitas antibakteri isolat Bakteri Asam
Laktat (BAL) yang diisolasi dari saluran pencernaan ikan naleh terhadap pertumbuhan Aeromonas hydrophila ATCC 35654. Isolasi BAL dilakukan dengan menggunakan media de Man, Rogosa and Sharpe agar (MRSA) secara aseptis. Sebanyak tiga belas isolat (NJ1-1, NJ1-2, NJ1-3, NJ1-4, NJ1-6, NJ1-7, NJ1-9, NJ1-10, NJ1-11, NJ1-13, NJ1-14, NJ1-15, dan NJ1-16) dikarakterisasi berdasarkan morfologi koloni, pewarnaan Gram, pewarnaan endospora, dan uji biokimia seperti TSIA, SIM, dan MRVP. Uji aktivitas antibakteri dilakukan dengan metode difusi cakram. Hasil karakterisasi berdasarkan ciri morfologi koloni BAL adalah berbentuk bundar berwarna putih (69,3%) dan krem (30,7%), tepian koloni licin (100%), serta elevasinya cembung (77%) dan timbul (23%). Ciri morfologi sel BAL adalah Gram positif, berbentuk kokus (92,3%) dan basil (7,7%), serta tidak membentuk endospora. Hasil uji TSIA menunjukkan fermentasi homofermentatif, hasil negatif pada uji indol dan VP, serta hasil positif pada uji MR. Aktivitas antibakteri terhadap Aeromonas hydrophila isolat NJ1-2, NJ1-3, NJ1-6, NJ1-9, NJ1-10, NJ1-14, dan NJ1-16 rata-rata zona hambat ≤ 3 mm yang tergolong lemah. Sedangkan isolat NJ1-1, NJ1-4, NJ1-7, NJ1-11, NJ1-13, dan NJ1-15 tidak menunjukkan adanya zona hambat. Penelitian ini diharapkan dapat menjadi dasar dalam pengembangan probiotik sebagai alternatif pengendalian biologis di bidang akuakultur.

Kata kunci: Aeromonas hydrophila, aktivitas antibakteri, Bakteri Asam Laktat (BAL), Barbonymus sp., probiotik

The naleh fish (Barbonymus sp.) is an endemic freshwater species inhabiting river ecosystems in West Aceh, particularly in Nagan Raya Regency. This study aimed to investigate the characteristics and antibacterial activity of lactic acid bacteria (LAB) isolates obtained from the gastrointestinal tract of naleh fish against Aeromonas hydrophila ATCC 35654. LAB were isolated aseptically using de Man, Rogosa and Sharpe agar (MRSA). A total of thirteen isolates (NJ1-1, NJ1-2, NJ1-3, NJ1-4, NJ1-6, NJ1-7, NJ1-9, NJ1-10, NJ1-11, NJ1-13, NJ1-14, NJ1-15, and NJ1-16) were selected for characterization based on colony morphology, Gram staining, endospore staining and biochemical tests including TSIA, SIM and MR-VP. Antibacterial activity was assessed using the disc diffusion method. Colony morphology of LAB isolates showed circular colonies with white (69.3%) and cream (30.7%) pigmentation, smooth margins (100%) and convex (77%) or raised (23%) elevation. Cell morphology showed gram-positive bacteria, predominantly cocci (92,3%) and bacilli (7,7%), and no endospore formation. TSIA test results indicated homofermentative metabolic properties; the isolates were negative for indole and VP and positive for MR. Antibacterial activity against A. hydrophila showed that isolates NJ1-2, NJ1-3, NJ1-6, NJ1-9, NJ1-10, NJ1-14, and NJ1-16 produced weak zones of inhibition (≤ 3 mm), whereas isolates NJ1-1, NJ1-4, NJ1-7, NJ1-11, NJ1-13, and NJ1-15 showed no zones of inhibition. These results may serve as a basis for the development of LAB-based probiotics as alternative biological control agents in aquaculture. Keywords: Aeromonas hydrophila, antibacterial, Barbonymus sp., Lactic Acid Bacteria, probiotics