Skrining bakteri asam laktat proteolitik pada fermentasi susu

WATTIMENA, Martha L, Dr.Ir. Endang S. Rahayu

2004 | Tesis | S2 Ilmu dan Teknologi Pangan

Penelitian ini bertujuan untuk menyeleksi bakteri asam laktat yang mempunyai kemampuan proteolitik selama fermentasi susu dan mempelajari suhu fermentasi, pH optimum dan konsentrasi substrat skim terhadap aktivitas proteolitik bakteri asam laktat. Hipotesa yang diajukan adalah bakteri asam laktat mempunyai kemampuan proteolitik memecahkan kasein susu selama fermentasi susu. Metode uji proteolitik digunakan media MRS agar + 2% skim, BAL yang menunjukkan zona jernih disekeliling koloni merupakan bakteri asam laktat proteolitik. Bakteri asam laktat yang terseleksi kemudian diuji aktivitas proteolitik dan pengaruh kondisi lingkungan seperti pH, suhu fermentasi , dan konsentrasi substrat skim terhadap aktivitas proteolitik ekstraseluler maupun proteolitik intraseluler Hasil uji proteolitik dari ke 21 isolat hanya 6 isolat yang mempunyai kemampuan proteolitik yaitu Lactobacillus acidophillus FNCC 0051, Lactobacillus bulgaricus FNCC 0041. Lactobacillus casei FNCC 0090, Lactobacillus sp. Dad 13, Lactococcus lactis FNCC 0120, Streptococcus thermophillus FNCC 0040. Aktivitas proteolitik bakteri asam laktat dipengaruhi oleh pH, Suhu dan Konsentrasi substrat, untuk mencapai aktivitas proteolitik tertinggi pH optimum 6,5, suhu 40°C - 45°C dan konsentrasi substrat 12,5%. Isolat Lactococus lactis FNCC 0120 menunjukkan aktivitas proteolitik Ekstraseluler tertinggi sedangkan aktivitas proteolitik Intraseluler dihasilkan oleh Lactobacillus sp Dad 13 dibandingkan dengan bakteri asam laktat yang lain.

The recent study has aim at selecting lactic acis bacteria having a proteolytical capacity during milk fermentation and studying the fermentation temperature, optimum pH and concentration of skim substrate to the proteolytical activity of lactic acid bacteria. Hypothesis proposed is the lactic acid bacteria has a proteolytical capacity to break the milk casein during the milk fermentation. A proteolytical test method used in a media of MRS agar + 2% skim, the lactic acic bacteria showing a clear zone around a colony is the proteolytic lactic acid bacteria. The selected lactic acid bacteria then tested for its proteolytical activity and some effects of the environmental conditions such as pH, fermentation temperature, and concentration of skim substrate to the extra-cell proteolytical and intra-cell proteolytical activities. From 21 isolates of proteolytical test result there are merely 6 isolates having proteolytical capacities that is Lactobacillus acidophilus FNCC 0051, Lactobacillus bulgaricus FNCC 0041, Lactobacillus casei FNCC 0090, Lactobacillus sp Dad 13, Lactobacillus lactis FNCC 0120, and Streptococcus thermophillus FNCC 0040. The proteolytical activity of lactic acid bacteria is influenced by pH, Temperature and Substrate Concentration, to reach the highest proteolytical activity oh optimum pH 6,5, temperature 40°C — 45°C and substrate concentration 12,5%. Isolate of Lactobacillus lactis FNCC 0120 showed the highest extra-cell proteolytical activity while the intra-cell proteolytical activity resulted from Lactobacillus sp Dad 13 was compared with other lactic acid bacteria.

Kata Kunci : Teknologi Pangan,Fermentasi Susu,Skrining Bakteri, Biogenic peptide, Fermented Milk, Proteolitic Activity