Artikel Ilmiah : B1A022201 a.n. DIMAS DWI PAMBUDI
| NIM | B1A022201 |
|---|---|
| Namamhs | DIMAS DWI PAMBUDI |
| Judul Artikel | Uji Antibakteri Isolat Bakteri Asam Laktat dari Yogurt Homemade dan Komersial terhadap Escherichia coli |
| Abstrak (Bhs. Indonesia) | Escherichia coli merupakan bakteri patogen yang berpotensi mencemari susu dan produk fermentasinya sehingga dapat menyebabkan gangguan kesehatan. Salah satu pendekatan alami untuk menghambat pertumbuhan bakteri tersebut adalah pemanfaatan bakteri asam laktat (BAL) yang menghasilkan senyawa antimikroba, seperti asam organik, hidrogen peroksida, dan bakteriosin. Yogurt merupakan salah satu sumber BAL yang potensial tetapi perbedaan proses fermentasi dan penggunaan kultur starter pada yogurt homemade dan yogurt komersial diduga menghasilkan isolat BAL dengan karakteristik serta aktivitas antibakteri yang berbeda. Penelitian ini bertujuan untuk mengisolasi, mengarakterisasi, dan memverifikasi genus isolat BAL dari yogurt homemade dan yogurt komersial, mengevaluasi aktivitas antibakteri supernatan yang dihasilkan oleh isolat BAL terhadap E. coli, serta membandingkan aktivitas antibakteri isolat yang berasal dari kedua jenis yogurt tersebut. Penelitian ini dilakukan melalui tahap isolasi dan karakterisasi BAL berdasarkan karakter makromorfologi, mikromorfologi, biokimia, serta fisiologis (suhu dan pH), dilanjutkan dengan verifikasi genus, pengujian aktivitas antibakteri terhadap E. coli menggunakan metode difusi cakram, serta identifikasi senyawa antibakteri. Penelitian ini merupakan penelitian eksperimental menggunakan Rancangan Acak Lengkap (RAL) pola faktorial dengan dua faktor, yaitu delapan isolat BAL yang berasal dari yogurt homemade dan yogurt komersial serta dua jenis supernatan, yaitu supernatan bebas sel (SBS) dan supernatan bebas sel ternetralisasi (SBSN), dengan tiga kali ulangan sehingga diperoleh 48 satuan percobaan. Variabel bebas penelitian meliputi isolat BAL dan jenis supernatan, sedangkan variabel terikat adalah aktivitas antibakteri isolat BAL terhadap E. coli. Parameter yang diamati meliputi lebar zona hambat serta karakter morfologi, fisiologi, dan biokimia isolat BAL. Data karakterisasi dianalisis secara deskriptif dengan membandingkan karakter isolat berdasarkan Bergey's Manual of Determinative Bacteriology, sedangkan data aktivitas antibakteri dianalisis menggunakan two-way Analysis of Variance (ANOVA) pada taraf nyata 5% dan dilanjutkan dengan uji Duncan's Multiple Range Test (DMRT) karena terdapat pengaruh yang signifikan. Penelitian ini berhasil mengisolasi delapan isolat BAL dari yogurt homemade dan komersial. Berdasarkan karakter morfologi, fisiologi, dan biokimia, empat isolat diduga termasuk ke dalam genus Streptococcus dan empat isolat lainnya diduga termasuk ke dalam genus Lactobacillus. Hampir seluruh isolat menunjukkan aktivitas antibakteri terhadap E. coli, kecuali kombinasi perlakuan isolat K2-2 SBSN yang tidak membentuk zona hambat. Lebar zona hambat terhadap E. coli berkisar antara 0,00–13,50 mm. Hasil analisis menunjukkan bahwa faktor isolat, jenis supernatan, dan interaksi keduanya berpengaruh sangat nyata terhadap aktivitas antibakteri terhadap E. coli. Aktivitas antibakteri pada perlakuan SBS menunjukkan rerata lebar zona hambat sebesar 4,95 mm yang lebih tinggi dibandingkan perlakuan SBSN yang hanya sebesar 1,93 mm. Isolat BAL dari yogurt homemade menunjukkan rerata lebar zona hambat yang lebih tinggi yakni 3,91 mm dibandingkan isolat dari yogurt komersial sebesar 2,96 mm. Hasil karakterisasi menunjukkan bahwa aktivitas antibakteri isolat BAL diduga melibatkan senyawa yang aktif pada kondisi asam serta senyawa yang tetap aktif setelah netralisasi. Aktivitas antibakteri yang tersisa setelah perlakuan SBSN pada tujuh isolat diduga berasal dari senyawa protein atau peptida yang diduga berupa bakteriosin. |
| Abtrak (Bhs. Inggris) | Escherichia coli is a pathogenic bacterium that potentially contaminates milk and its fermented products, leading to health disorders. A natural approach to inhibit the growth of these bacteria is the utilization of lactic acid bacteria (LAB), which produce antimicrobial compounds such as organic acids, hydrogen peroxide, and bacteriocins. Yogurt is a potential source of LAB, but differences in the fermentation process and the use of starter cultures in homemade and commercial yogurt are suspected to yield LAB isolates with distinct characteristics and antibacterial activities. This study aims to isolate, characterize, and verify the genus of LAB isolates from homemade and commercial yogurt, evaluate the antibacterial activity of the supernatant produced by the LAB isolates against E. coli, and compare the antibacterial activities of isolates derived from both types of yogurt. This research was conducted through the stages of LAB isolation and characterization based on macromorphological, micromorphological, biochemical, and physiological (temperature and pH) characteristics. This was followed by genus verification, antibacterial activity testing against E. coli using the disc diffusion method, and identification of antibacterial compounds. The study was an experimental research utilizing a Completely Randomized Design (CRD) with a factorial pattern consisting of two factors: eight LAB isolates derived from homemade and commercial yogurt, and two types of supernatants—cell-free supernatant (CFS) and neutralized cell-free supernatant (NCFS). The experiment was conducted with three replications, resulting in 48 experimental units. The independent variables included the LAB isolates and the types of supernatant, while the dependent variable was the antibacterial activity of the LAB isolates against E. coli. The observed parameters included the diameter of the inhibition zone as well as the morphological, physiological, and biochemical characteristics of the LAB isolates. The characterization data were analyzed descriptively by comparing the isolate traits based on Bergey's Manual of Determinative Bacteriology. Meanwhile, the antibacterial activity data were analyzed using a two-way Analysis of Variance (ANOVA) at a 5% significance level, followed by Duncan's Multiple Range Test (DMRT) due to the presence of significant effects. This study successfully obtained eight LAB isolates from homemade and commercial yogurt. Based on morphological, physiological, and biochemical characteristics, four isolates were suspected to belong to the genus Streptococcus, while the other four were suspected to belong to the genus Lactobacillus. Almost all isolates demonstrated antibacterial activity against E. coli, except for the treatment combination of isolate K2-2 NCFS, which did not form an inhibition zone. The width of the inhibition zone against E. coli ranged from 0.00 to 13.50 mm. The analysis results indicated that the isolate factor, supernatant type, and their interaction had a highly significant effect on the antibacterial activity against E. coli. The antibacterial activity in the CFS treatment showed an average inhibition zone width of 4.95 mm, which was higher than the NCFS treatment that only reached 1.93 mm. LAB isolates from homemade yogurt exhibited a higher average inhibition zone width of 3.91 mm compared to isolates from commercial yogurt at 2.96 mm. The characterization results suggested that the antibacterial activity of the LAB isolates likely involves compounds that are active under acidic conditions as well as compounds that remain active after neutralization. The residual antibacterial activity observed after the NCFS treatment in seven of the isolates is presumed to originate from protein or peptide compounds, suspected to be bacteriocins. Keywords: antibacterial activity, lactic acid bacteria, Escherichia coli, supernatant, yogurt |
| Kata kunci | aktivitas antibakteri, bakteri asam laktat, Escherichia coli, supernatan, yogurt |
| Pembimbing 1 | Dra. Dyah Fitri Kusharyati, M.P. |
| Pembimbing 2 | Taruna Dwi Satwika, S.Si., M.Si. |
| Pembimbing 3 | - |
| Tahun | 2026 |
| Jumlah Halaman | 83 |
| Tgl. Entri | 2026-08-21 13:43:09.263527 |