Preparation of fermented seaweed broth with fibrinolytic activity by Bacillus subtilis natto

• Main Authors: Tzu-Chun Lin, 林姿君
• Other Authors: Guo-Jane Tsai
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/47189746123613428300

碩士 === 國立臺灣海洋大學 === 食品科學系 === 96 === The aim of this research is to ferment seaweed broth with fibrinolytic activity by Bacillus subtilis natto. Four standard strains of B. subtilis natto from Bioresource Culture Research Center (BCRC) and 9 isolates from commercial natto products were collected. The capability for the fibrinolytic enzyme (FE) production by these collected strains was screened first by a fibrin plate. The diameters of the clear zone for the 9 isolates were 25-26 mm, which were much higher than that of 12-20 mm by the 4 standard strains. Therefore, these 9 isolates were chosen for further investigation of their growth and FE production in five edible seaweeds of Gracilaria tenuistipitata, Porphyra dentate, Undaria pinnatifida, Ulva lactuca and Laminaria japonica. After incubation at 37oC for 48 h, none of the tested 9 isolates can grow in the 1 % Laminaria japonica suspension. However, all of the 9 isolates grow well in the rest 4 seaweeds. The cell counts of the 9 isolates in the suspensions of Ulva lactuca, Porphyra dentate, Gracilaria tenuistipitata and Undaria pinnatifida were increased by 3.24-3.88, 2.98-3.71, 2.91-3.60 and 2.82-3.37 log cfu/mL, respectively. However, the FE activities with decreasing order for the fermented seaweed products by the tested 9 strains were Porphyra dentate, Undaria pinnatifida, Gracilaria tenuistipitata and Ulva lactuca.Their FE activity were 1.71, 1.33, 1.23, 1.15 U/mL, respectively. Overall, the highest FE activities of 1.71 U/mL were obtained in Porphyra dentate product fermented by the N2 isolate. Therefore, the N2 strain was chosen as the experimental strains and Porphyra dentate was chosen as the raw material. Factors of Porphyra dentate concentration, additions of sugars, nitrogen sources, salts, or oils, inoculums cultivation time and size, fermenting temperature, initial pH of medium and shaking rate on cell growth and FE production by N2 isolate in Porphyra dentate suspension were investigated. The optimized conditions for FE production were concluded as follows : 3 % Porphyra dentate suspension added with 1 % peanut oil is adjusted with intial pH 6~7 and inoculated with 6 % (v/v) of N2 culture that has been cultivated in TSB for 24 hr. After incubation at 37 oC with 200 rpm for 72 hr the FE activity was 36.61 U/mL, which is 21.41 times of FE activity from original un-optimized fermented Porphyra product.