Difference between revisions of "Team:SDSZ China/Our Solution"

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<h2>WHAT IS CHITIN</h2>
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Sea food is almost a common delicacy to everyone. Boston is famous for lobster; Japan is famous for all kinds of sashimi. Few people have paid attention to the huge amount of shells being tossed away annually, but, in fact, there is a special kind of chemical component forming the crustaceans’  outer bones. This is CHITIN（(C8H13O5N)n), an abundant natural macromolecular substances that is rich in common crustaceans such as  insects or crabs. In most crustaceans, chitin is combined with calcium carbonate and produces a much stronger composite. This composite material is much harder and stiffer than pure chitin, and is tougher and less brittle than pure calcium carbonate. Chitin is insoluble and lack of bioactivity, therefore not widely used in industry.
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<h2>WHAT IS CHITOSAN</h2>
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Because of chitin’s insolubility and bioactivity, it is usually converted by deacetylation to soluble and bioactive CHITOSAN ((C8H13NO5)n (203.19)n). It is white powder and has relatively more industrious usages:
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Thus it led us think of the promising biotechnology treatment by using chitin-active enzymes classified from nature to produce chitosan. The only by-product is acetic acid, which is far less harmful to environment than concentrated acid and alkali.  
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Agriculture: used in seed treatment and biopesticide, helping plants to fight off fungal infections.
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Winemaking: used as fining agent, helping to prevent spoilage.
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Industry: used in a self-healing polyurethane paint coating.
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Medicine: used in bandages, helping to reduce bleeding and serving as an antibacterial agent; used to help deliver drugs through the skin.
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There are two kinds of active enzymes found in creatures that are related to the transformation of chitin. Chitinase is able to hydrolyze chitin yielding monomers. Chitin deacetylase (known as CDA) could hydrolyze the acetylamino group on chitin, directly yielding chitosan. Our research focused more on CDA. </p>
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But the problem is that available source of chitin and currently examined CDAs are unmatched. The only industrial-available source of chitin is the especially high-crystallized chitin from shrimps and crab shells. As reported, CDA has been found in bacteria, molds and insects, but the examined ones are all inactive toward crystallized chitin. This is the reason why enzymolysis is not widely used in chitosan industry. </p>
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Thus, separation, identification, and production of crystal-chitin-active-enzymes are crucial to solving this problem, hence accelerate the industrialization of environmental-friendly chitosan production considerably, and give instruction to research on <i>arthropodic ecdysis </i>and aquacultural production. </p>
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So we planned to obtain the genes of creatures who can produce CDA, and then overlap the gene of CDA, the gene of chitinase, and the gene of a protein that can combine with chitin, whose main function is to accelerate the reaction. Then we would let the competent cells translate these genes into proteins together and react spontaneously. Once target protein shows up, we would then cultivate the bacteria, measure the liveliness of the synthesized enzyme, and determined maximum yield rate. </p>
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The goal we want to achieve is to maximize the range of chitin’s mass we could break down, the production rate, and the purity of chitosan. </p>
  
  
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<h2>CURRENT CHITOSAN PRODUCTION</h2>
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The current technology of chitosan production is the treatment with concentrated alkali.
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The chitin/chitosan process involves the crushing and drying of crab shell or other suitable species of crustaceans such as shrimp shell waste. The product is processed with acid and alkaline in order to remove protein and calcium. The product is then further dried, grinded, and packaged as a finished or semi-finished product.
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A plant set-up would involve a number of pieces of equipment for grinding or particuli- zation, drying, acid and alkaline treatment, packaging and effluent treatment.
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Crushed shrimp waste was kept in a polyethylene bags at ambient temperature (28±2oC) for 24 hours for partial autolysis to facilitate chemical extraction of chitosan and to improve the quality of chitosan.
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3steps: Demineralization, Deproteinization and Deacetylation
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Demineralization: Demineralization of shrimp shell has been carried out with three different concentration of HCI (4%, 3%, 2%) at ambient temperature (28±2oC) with a solid to solvent ratio 1:5 (w/v) for 16 hours (Toan, 2009). The residue was washed and soaked in tap water until neutral pH.
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Deproteinization: Deproteinization of shrimp shell was done with 4% NaOH at ambient temperature (28±2oC) with a solid to solvent ratio 1:5 (w/v) for 20 hours (Toan, 2009). The residue was washed and soaked in tap water until neutral pH. Then purified chitin was dried until it was become crispy. Chitin flakes was grounded to small particle to facilitate deacetylation.
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Deacetylation: Removal of acetyl groups from chitin was experimented using four different concentration of NaOH (30%, 40%, 50%, 60%) at 650C temperature with a solid to solvent ratio 1:10 (w/v) for 20 hours. (Toan, 2009).The residue was washed until neutral pH with tap water. The resulting chitosan was then dried at cabinet dryer for 4 hours at 65±50 C and prepared for characterization.
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However, current chitosan production has exposed many drawbacks: deficiency over time and reactant, huge energy cost during the process, instability of product quality, unsafe condition for employees, and, especially, the destructive pollution of basic waste water. Acid and alkali wasted water can easily polluted waterbody and farmland. 
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Latest revision as of 23:00, 17 October 2018

iGem SDSZ_China 2018
...

Thus it led us think of the promising biotechnology treatment by using chitin-active enzymes classified from nature to produce chitosan. The only by-product is acetic acid, which is far less harmful to environment than concentrated acid and alkali.

There are two kinds of active enzymes found in creatures that are related to the transformation of chitin. Chitinase is able to hydrolyze chitin yielding monomers. Chitin deacetylase (known as CDA) could hydrolyze the acetylamino group on chitin, directly yielding chitosan. Our research focused more on CDA.

But the problem is that available source of chitin and currently examined CDAs are unmatched. The only industrial-available source of chitin is the especially high-crystallized chitin from shrimps and crab shells. As reported, CDA has been found in bacteria, molds and insects, but the examined ones are all inactive toward crystallized chitin. This is the reason why enzymolysis is not widely used in chitosan industry.

Thus, separation, identification, and production of crystal-chitin-active-enzymes are crucial to solving this problem, hence accelerate the industrialization of environmental-friendly chitosan production considerably, and give instruction to research on arthropodic ecdysis and aquacultural production.

So we planned to obtain the genes of creatures who can produce CDA, and then overlap the gene of CDA, the gene of chitinase, and the gene of a protein that can combine with chitin, whose main function is to accelerate the reaction. Then we would let the competent cells translate these genes into proteins together and react spontaneously. Once target protein shows up, we would then cultivate the bacteria, measure the liveliness of the synthesized enzyme, and determined maximum yield rate.

The goal we want to achieve is to maximize the range of chitin’s mass we could break down, the production rate, and the purity of chitosan.

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