No abstract

Susu mempunyai nilai nutrisi tinggi dan mengandung protein sebagai sumber peptida bioaktif yang berguna bagi kesehatan. Penelitian ini bertujuan untuk mengeksplorasi potensi peptida bioaktif dari susu kambing sebagai antimikroba dan antioksidan. Susu dihidrolisis menggunakan enzim tripsin, kimotripsin, pepsin atau protease Bacillus sp. E.13. Peptida yang diperoleh dipilah untuk aktivitas antimikroba dengan mencampurkan peptida dan bakteri Staphylococcus aureus, Listeria monocytogenes, Salmonella thyphimurium dan Escherichia coli sebanyak 10 6 CFU/mL dan diinkubasi pada suhu 37°C selama 2 jam dan ditumbuhkan pada Mueller Hinton agar. Aktivitas antimikroba ditentukan dengan membandingkan jumlah koloni bakteri yang tumbuh pada cawan dengan dengan jumlah koloni bakteri kontrol tanpa penambahan peptida. Aktivitas antioksidan ditentukan melalui uji 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) dan 2,2-diphenyl-1-picrylhydrazyl (DPPH). Aktivitas antimikroba terlihat pada peptida hasil hidrolisis susu kambing oleh pepsin pada suhu 37°C, pH 2 selama 90 menit dan protease Bacillus sp. E.13 pada suhu 55°C, pH 11 selama 30 and 60 menit tetapi aktivitas tersebut tidak terdeteksi pada peptida hasil hidrolisis protein dengan tripsin dan kimotripsin. Peptida dari hidrolisis protein oleh protease Bacillus sp. E.13 dapat menghambat Listeria monocytogenes, Salmonella thyphimurium dan Escherichia coli sampai 5 siklus log. Peptida antimikroba tersebut juga dapat meredam radikal ABTS sampai 86% dan radikal DPPH 9% pada konsentrasi 68 μg protein/mL. Hasil tersebut mengindikasikan bahwa protein susu kambing yang dihidrolisis dengan protease Bacillus sp. E.13 berpotensi sebagai antimikroba sekaligus sebagai antioksidan.

Aims: This study was to isolate, screen, and identify microorganisms from fermented food Red Oncom and Gembus that can produce fibrinolytic proteases. Methodology and results: Forthy-three isolates showed proteolytic activities on skim milk agar, while thirthy-eight of them showed fibrinolytic activities both on a fibrin plate and a fibrinogen zymography. The isolates that showed activity in fibrin plate and fibrinogen zymography with lower molecular weight and considered as safe were chosen and identified as Bacillus licheniformis and Bacillus pumilus by using API CHB kit and 16S rRNA. The novel fibrinolytic microorganisms were referred to as B. licheniformis RO3 and B. pumilus 2.g. Conclusion, significance and impact of study: Red Oncom and Gembus are potential sources of microbial fibrinolytic protease. This is the first time that Red Oncom and Gembus as Indonesian fermented foods based on soybean cake were shown having fibrinolytic microorganism. Microbial fibrinolytic enzymes from these fermented foods can be used for functional food formulation to prevent thrombosis and other related diseases.

The human feet and mouth are known as sources of methylated sulfides, which are produced by other microflora. Methylated sulfides could be oxidized by methylotrophic bacteria, which may result in odor reduction in human feet and mouth. In this study, we collected a total of 21 isolates from human feet, and 37 isolates from human mouth. These isolates were identified with biochemical test such as oxidase and catalase test and Gram staining assay. The presence of mxaF gene of methanol dehydrogenase was detected by PCR using specific primers. However, the result showed that most of the isolates did not possess mxaF gene. Hence, the methanol dehydrogenase (MDH) activity was also determined. From the total 21 isolates obtained from the feet, only 15 of them showed MDH activity whereas 23 isolates from the total 37 isolates obtained from teeth and tongue region also showed MDH activity. Isolate K25-3 (74.444 U/ml), K33-6 (79.815 U/ml), and K43-5 (69.259 U/ml) from human feet and M41L3 (135.926 U/ml), M27G2 (85.556 U/ml), and M51G1 (103.333 U/ml) from human mouth showed the highest total enzyme activity. Isolates with the highest total activity could be used for further studies such as purification of the enzyme and isolates characterization.