Production of Chitinase by Trichoderma Virens Ukm1 from Colloidal Chitin and Shrimp Waste
Shrimp waste being the main waste from marine industry is a source of surface pollution in coastal areas consisting of mainly protein, calcium carbonate and chitin. Chitin, the second most abundant biopolymer is a -(1,4)-linked N-acetyl-Dglucosamine (GluNac) heterogeneous polymer that has versati...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2007
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/5386/1/IB_2007_11a.pdf |
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| Summary: | Shrimp waste being the main waste from marine industry is a source of surface
pollution in coastal areas consisting of mainly protein, calcium carbonate and chitin.
Chitin, the second most abundant biopolymer is a -(1,4)-linked N-acetyl-Dglucosamine
(GluNac) heterogeneous polymer that has versatile biological and
agrochemical applications. Chitinase a glycosyl hydrolase is produced constitutively
as isozymes in fungus for de novo chitin metabolism. Chitin chains are converted
into chitooligosaccharides and GluNac reducing sugars by chitinase with specific
modes of action at the reducing ends. In this study, shrimp waste was pretreated with
chemical and physicochemical methods to determine the best pretreatment before
fermentation with a locally isolated fungus, Trichoderma virens UKM1. Experiments
in shake flasks and 2 L stirred tank reactor (STR) demonstrated sun dried ground
shrimp waste as the best pretreatment, 1 x 106 spores/mL as the best total spore
concentration and fermentation pH control at pH 6.0 as the most effective for
chitinase production. Subsequent optimisation in 2 L STR showed that fermentation
at 200 rpm and 0.33 vvm gave the highest chitinase productivity of 4.1 U/L/h and
5.97 U/L/h, respectively. Microbial chitin bioconversion employing optimal conditions in medium with colloidal chitin and medium with sun dried ground
shrimp waste as the sole carbon source showed an increase of 7.25 fold and 1.57 fold
in chitinase activity, respectively from shake flasks culture to 2 L STR. The
respiration rate (Qo2X) during the highest chitinase productivity was 3.864 mg of DO
g-1 of fungal biomass h-1 while the specific respiration rate (Qo2) was 20.337 mg of
DO g-1 of fungal biomass h-1 and the maximum specific growth rate, μmax was 0.0078
h-1 with the corresponding doubling time, td of 88.85 hours. Concentration and partial
purification of crude chitinase showed that ammonium sulphate precipitation at 80%
saturation gave highest chitinase activity in line with the results of enzymatic chitin
bioconversion from DNS chitinase assay and HPLC analysis. |
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