| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 102 === The effect of five parameters including yeast extract concentration, culture medium volume, shake speed, peptone concentration and agar concentration on the activity of agar-degrading enzyme (ADE) from bacterium FY by using experimental designs was investigated in this study. In 2-level factorial screening test, significant factors: yeast extract concentration, culture medium volume and shake speed were identified. To optimize the activity of ADE, the test ranges of yeast extract concentrations (%), culture medium volume (ml) and shake speed (rpm) were set at 0.1~0.3%, 25~125 ml and 75~175 rpm in response surface methodology (RSM) experiments, respectively. The result indicated that the ADE activity was increased from 265.9 (initial) to 600.1 U after optimization. In addition, 5-liter fermenter was employed for scale-up culture. Although the activity of ADE was only 382.2 U by the fermenter culture, enzyme harvest (volume) was increased 80-fold and cultivation time was reduced from 48 to 12 hours. By using TLC and HPLC analysis, it revealed that FY agarase belongs to β-agarase because the hydrolytic products of agarose digested by FY agarase are neoagaro- oligosaccharides. The oligosaccharides have been reportede to have biological activities. Because we found that the hydrolytic products of food-grade agar hydrolyzed by FY agarase are the same as those of analytical grade agarose, the use of food-grade agar for the neoagaro-oligosaccharide production can reduce cost. Moreover, it indicated that hydrolysis time plays an important role in the types of oligosaccharide dervatives from hydrolytic process.
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