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| 008 | 031003s2002 th uzm rtt 00| a1eng d | ||
| 035 | _a.b11900994 | ||
| 099 | 9 | _aAIT Thesis no.BP-02-09 | |
| 100 | 1 | _aIlankovan, Paraman | |
| 245 | 1 | 0 | _aEnzymatic preparation of chitin oligosaccharides |
| 260 |
_aBangkok : _bAsian Institute of Technology, _c2002 |
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| 300 | _a74 leaves | ||
| 490 | 1 |
_aThesis ; _vno. BP-02-09 |
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| 502 | _aThesis (M.Sc.) - Asian Institute of Technology, 2002 | ||
| 500 | _aA thesis submitted in partial fulfillment of the requirements for the degree of Mater of Science, School of Environment, Resources and Development | ||
| 520 | _aThe aim of this study is to produce N-acetyl glucosamine and water-soluble Nacetyl chito oligosaccharides using commercially available enzymes. There are altogether 20 enzymes examined. Pepsin and cellulase showed comparatively higher chitinolytic activity among the tested non-specific enzymes. Pepsin primarily produced dimer and small amount of monomer and trimer units. Cellulase mainly produced monomer units. High c1ystallinity of chitin is the major factor which limits the enzymatic hydrolysis to proceed. Modifications on chitin were important for partial destruction of crystallinity. The products yield from enzymatic hydrolysis was much better in decrystallized chitins compared to non-decrystallized natural chitins. Especially the suspension forms of the decrystallized chitins were more susceptible to enzymatic hydrolysis than solid form of chitins. The modified chitins were found to be more susceptible to enzymatic degradation. Alkaline treatment to produced amorphous chitin, phosphoric acid treatment, production of super fine chitin were the methods significantly reduced the crystallinity of chitin. Hydrochloric acid treatment did not show significant reduction in crystalline nature of chitin. Enzymatic reactions on two type chitins, a. chitin from shrimp, crab and {3 chitin from squid pen, cuttle fish, did not show any significant different in hydrolysis, although {3 chitin is relatively less crystalline in nature. pH, temperature, enzyme concentration, substrate concentration and enzyme to substrate ratio have interactive influence on rate and degree of hydrolysis. But, they have no influence on pattern of hydrolysis. The product composition remained same at all the conditions. The optimum temperature for chitinolytic activity of pepsin and cellulase was found to be 44°C and the optimum pH was 5.4 and 4.2 respectively. Pepsin shows stable activity in a wide pH range between 4.2 and 5.7 at its optimum temperature whereas cellulase was very sensitive to pH. Enzyme concentration has a significant effect on the degree of fragmentation. The product yield significantly increased as enzyme concentration increase. The total product concentration in hydrolysate increased with the increase of substrate concentration but the unit yield decreased. Hence, moderate ratio of enzyme to substrate is needed to achieve a yield with higher efficiency of production. The optimum ratio was of enzyme to substrate found at 20-40% for pepsin and 40 - 50% for cellulase. Enzymatic hydrolysis of chitin by pepsin produced 2.76% monomer, 8.62% dimer and 2.25 % trimer whereas cellulase produced 8.09% of monomer and 1.8% of dimer when phosphoric chitin was used as substrate under optimized conditions. The total degree of hydrolysis of chitin by pepsin was 14.21 %, 12.32% and 12.85% when liquefied phosphatechitin, amorphous-chitin and super fine chitins were used as substrate respectively. Cellulase obtained 9.89 % and 8.72 % of total yield when using phosphate and amorphous chitin as substrate, respectively. The optimum time for the e~ymatic hydrolysis was found to be between 12 and 24 hours. Beyond that the product yield increased at low rate. There are chances for product loss in longer incubation due to microbial spoilage. A severe reduction in enzymatic activity was observed after 24 hours incubation due to both, adsorption of enzyme on chitin particles and enzyme itself loose its activity in long period of incubation. No product inhibition has been observed in this study. | ||
| 650 | 0 | _aChitin | |
| 650 | 0 | _aChitosan | |
| 650 | 0 | _aEnzymes | |
| 700 | 1 |
_aStevens, Willem Frans, _eChairperson |
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| 700 | 0 |
_aSuwalee Chandrkrachang, _eExamination Committee |
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| 700 | 1 |
_aTrankler, Josef, _eExamination Committee |
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| 700 | 0 |
_aAttaya Kungsuwan, _eExamination Committee |
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| 710 | 2 |
_aThe Royal Government of Netherlands, _eScholarship Donor |
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| 810 | 2 |
_aAsian Institute of Technology. _tThesis ; _vno. BP-02-09 |
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| 856 |
_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B08092 |
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