Study on Chitinolytic Enzymes from Serratia marcescens NTU-17
Date Issued
2008
Date
2008
Author(s)
Lin, Yuan-Ju
Abstract
Abstract-acetylchitooligosaccharides (degree of polymerization 4-6) have specific biological activities such as antitumor activity and immuno-enhancing effects. In this study, we aimed to isolate environmental microorganisms which could produce enzymes to hydrolyze chitin into N-acetylchitooligosaccharides. At the initial stage, we hydrolyzed colloidal chitin with crude microbial enzymes and analyzed the products by HPLC. From this screening, we found that the crude enzyme from one bacterial isolate could hydrolyze chitin and produce N-acetylchitooligosaccharides. The bacterial strain was identified by 16S rRNA sequencing and phylogenetic analysis to belong Serratia marcescens and was named S. marcescens NTU-17. We used central composite design (CCD) of response surface methodology (RSM) to obtain the optimal culture condition for chitinase production: 0.4 g/l colloidal chitin, 1.6 g/l casein, 30。C and pH 7.5; the highest chitinase activity was produced at 18 hours after inoculation. The crude enzyme from culture broth of S. marcescens NTU-17 was subjected to successive steps of purification. After ammonium sulfate fractionation (35-70%), gel filtration-Sephacryl 200 chromatography, and DEAE-Sephacel column chromatography, two species of chitinase were purified and the molecular weights were determined by SDS-PAGE to be 53 kDa (chitinase 1) and 39 kDa (chitinase 2). The chitinase activity of chitinase 1 and 2 were also verified by an in-gel chitinase activity assay. After purification, the specific activity of chitinase was increased by 2.5 fold and the yield was 12%. Chitinase 1 exhibited the optimal activity at pH 3 and 50℃, and chitinase 2 showed the optimal activity at 30℃ and similar activities at pH 3-12.
Subjects
chitin
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-97-R95631003-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):ee83e1efe92649117f4434fa3c68f632