Su Y C, Sheu C S, Chien J Y, Tzan T K
Department of Agricultural Chemistry, National Taiwan University, Taipei, Republic of China.
Proc Natl Sci Counc Repub China B. 1991 Jul;15(3):131-9.
Microbial beta-fructofuranosidases with transfructosylating activity can catalyze the transfructosylation of sucrose and synthesize fructooligosaccharides. Aspergillus japonicus NTU-1249 isolated from natural habitat was found to produce a significant amount of beta-fructofuranosidase with high transfructosylating activity and to have the potential for industrial production of fructooligosaccharides. In order to improve it's enzyme productivity, the medium composition and the cultivation conditions for A. japonicus NTU-1249 were studied. A. japonicus NTU-1249 can produce 83.5 units of transfructosylating activity per ml broth when cultivated in a shaking flask at 28 degrees C for 72 hours with a modified medium containing 80 g/l sucrose, 15 g/l soybean flour, 5 g/l yeast extract and 5 g/l NaCl at an initial pH of 6.0. The enzyme productivity was also optimized by submerged cultivation in a 5-litre jar fermentor with aeration at 1.5 vvm and agitation at 500 rpm. Under these operating conditions, the productivity of transfructosylating activity increased to 185.6 U/ml. Furthermore, the transfructosylating activity was improved to 256.1 U/ml in 1,000-litre pilot-scale fermentor. Enzymatic synthesis of fructooligosaccharides by beta-fructofuranosidase from A. japonicus NTU-1249 was performed in batch type by adding 5.6 units of transfructosylating activity per gram of sucrose to a 50% (w/v) sucrose solution at pH 5.0 and 50 degrees C. The yield of fructooligosaccharides was about 60% after reaction for 24 hours, and the syrup produced contained 29.8% (w/v) fructooligosaccharides, 15.2% (w/v) glucose and 5.0% (w/v) sucrose.
具有转果糖基活性的微生物β-呋喃果糖苷酶可催化蔗糖的转果糖基化反应并合成低聚果糖。从自然环境中分离得到的日本曲霉NTU-1249被发现能产生大量具有高转果糖基活性的β-呋喃果糖苷酶，且具有工业生产低聚果糖的潜力。为了提高其酶产量，对日本曲霉NTU-1249的培养基组成和培养条件进行了研究。当在摇瓶中于28℃培养72小时，使用含有80g/L蔗糖、15g/L大豆粉、5g/L酵母提取物和5g/L氯化钠、初始pH为6.0的改良培养基时，日本曲霉NTU-1249每毫升发酵液可产生83.5单位的转果糖基活性。通过在5升罐式发酵罐中进行深层培养，通气量为1.5vvm，搅拌速度为500rpm，酶产量也得到了优化。在这些操作条件下，转果糖基活性产量提高到了185.6U/ml。此外，在1000升中试规模发酵罐中转果糖基活性提高到了256.1U/ml。通过在pH5.0和50℃下向50%（w/v）蔗糖溶液中每克蔗糖添加5.6单位转果糖基活性，以分批方式进行日本曲霉NTU-1249的β-呋喃果糖苷酶催化合成低聚果糖。反应24小时后，低聚果糖的产率约为60%，所产糖浆含有29.8%（w/v）的低聚果糖、15.2%（w/v）的葡萄糖和5.0%（w/v）的蔗糖。
