Proteolytic activity characterization of bacteria isolated from Malaysian traditional fermented food
Three types of bacteria strains, which are Bacillus sp., Enterococcus gallinarum and Bacillus thuringiensis have been isolated previously from Malaysiantraditional fermented food. The proteolytic activities of the three strains werescreened on skim milk agar plate. After 24 hours of incubation at 37...
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| Format: | Thesis |
| Language: | English |
| Published: |
2014
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| Subjects: | |
| Online Access: | http://eprints.utm.my/48794/ http://eprints.utm.my/48794/25/NajihahIsmailMFBME2014.pdf |
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| Summary: | Three types of bacteria strains, which are Bacillus sp., Enterococcus gallinarum and Bacillus thuringiensis have been isolated previously from Malaysiantraditional fermented food. The proteolytic activities of the three strains werescreened on skim milk agar plate. After 24 hours of incubation at 37°C, proteolyticactivity was observed based on holozone formation on the skim milk agar plate witha diameter of 0, 1.9, and 3.2 cm respectively for Bacillus sp., Enterococcusgallinarum and Bacillus thuringiensis. The proteolytic activities of all the strainswere characterized based on optimum temperature, temperature stability, optimumpH, pH stability, substrate specificity and effect of metal ions towards activity. Allthree strains showed optimum activity at 50°C. The optimum pH for Bacillus sp. andBacillus thuringiensis were pH 8.5, while Enterococcus gallinarum showedmaximum enzyme activity of 0.068±0.003 U/ml at pH 7.5. The proteolytic activity ofthe bacteria were stable in the temperature range of 30°C to 50°C and exhibited rapiddecrease in activity when incubated at 60°C for 60 minutes. Proteolytic activity of allstrains was stable at a broad pH range from pH 4.5 to pH 10.6. The bacteria strainsdisplayed high activity for casein, gelatin and fibrin but showed very low activity forbovine serum albumin. Proteolytic activity of Bacillus sp. was enhanced by Cu2+,Ca2+, Mg2+, Fe2+ and Zn2+, while the proteolytic activity of Enterococcus gallinarumwas only slightly enhanced by Zn2+. |
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