Studies on Chitinolytic Enzymes from Aeromonas sp. No. 16

• Main Authors: Chen,Chun-Jen, 陳俊任
• Other Authors: Su,Yuan-Chi;Hiang,Jan-Hsiung
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/24841666705890767379

碩士 === 國立臺灣大學 === 農業化學系 === 81 === The partially hydrolyzed products of chitin and chitosan, N- acetylchitooligosaccharides and chitooligosaccharides, are of special interest because these oligosaccharides have been evalu- ated in various applications.This study focused on the production of N-acetylchitooligosaccharides by microbial enzymes. Crab shell chitin prepared by treating crab shell with acid and alkali was used as a substrate for isolating chitinolytic mi- croorganisms. Among the 103 isolated strains, strain No. 16 appeared to be the most potential chitinase-producing strain. It was identified belonging to the genus Aeromonas and named Aero- monas sp. No. 16. When the medium contained 1.5% colloidal chitin , 2.0% tryp- tone and 1.5% yeast extract with initial pH 10, Aeromonas sp. No. 16 could produce 1.4 units/milliliter of chitinase activity after 24 hours cultivation in 500 mL Hinton''''s flask. Using crys- talline chitin as substrate for enzyme productionin a 5L fermen- tor with temperature at 30℃, aeration at 1 vvm, agitation at 400 rpm and pH controlled between 7 and 8, chitinase activity could reach 1.5 units/milliliter after 30 hours cultivation. Chitin and N-acetylglucosamine were both found to be inducers for chitinase synthesis by Aeromonas sp. No. 16, on the other hand, addition of other carbohydrates would repress enzyme production with different degrees. Crude enzyme hydrolyzed chitin and produced N-acetylglucosa- mine as main product ,hydrolyzed chitosan with unknown products formation, which was supposed to be hetero- chitooligosaccharide. In crude enzyme, chitinase activity was most active at pH 6.0 and 50℃, and was stable at pH between 5 and 9 and at temperature be- low 40℃. β-N-acetyl-D- glucosaminidase was less stable at 40℃ and supposed to be an intracellular enzyme. After PAGE and acti-