Chitin

Question 1

What is the monomer of chitin?

Answer 1

Chitin (C8H13O5N)n is a long-­‐chain polymer of a N-­‐ acetylglucosamine, a derivative of glucose.

(Second most abundant polysaccharide after cellulose)

Question 2

Where is chitin found?

Answer 2

Common structural polymer especially in crustacea, exoskeletons

Question 3

How are the polymer chains of chitin and cellulose different?

Answer 3

Chitin has an additional acetyl group attached.

Question 4

What is the benefit of chitin over cellulose?

Answer 4

Nitrogen essential for life and separates cellulose from chitin. Cellulose is an incomplete food source – whereas chitin can provide carbon & nitrogen.

Question 5

Talk about the composite material formed with chitin in crustacea.

Answer 5

In crustacea – forms a composite material with calcium carbonate. (lobster shells are made of a composite material of chitin interlaced with chalk).

Chitin is interwoven like steel in construction.

Question 6

Where and when was chitin discovered?

Answer 6

Discovered in 1811 by Braconnot in cell walls of mushrooms

1843 found in insects and plants

Question 7

Give some of chitins useful properties.

Answer 7

• Biocompatible, biodegradable, bioabsorbable - possible use as a film in packaging.
• Antibacterial and wound healing properties
• Low immunogenicity (good for biomedical applications) - possibility of use in drug delivery.

Question 8

How is chitin currently used in industry?

Answer 8

Thickener and stabiliser in food

—— Flexible and strong, use in a surgical thread (also biodegradable)

—— Paper manufacture

—— Stabiliser for pharmaceuticals

—— Component in dyes and adhesives

Question 9

What is chitosan?

Answer 9

—— Chitosan is formed when chitin is solubilised in water

—— First produced in 1859

—— 1940s -­‐ many patents

—— Dumping of shellfish waste was banned in 1970s and processing of chitin expanded as a way of turning waste into products

—— Produced by the deacetylation of chitin

Question 10

How is chitosan produced from chitin?

Answer 10

Chitosan – a product produced from chitin in a process called deacetylation.

Manufactured from waste crab and shrimp shell material

—— Water soluble bioadhesive

—— Improved seed protection in crop use

—— Wide use in agriculture

—— Also used to fight obesity and hypercholesterolemia

—— Binds to lipids and decreases their absorption

Question 11

Where is chitin found in other organisms?

Answer 11

—— Chitin is found in the cell walls of bacteria and fungi

—— Sheaths of parasitic nematodes

—— Chitinases are produced as protection from chitin containing organisms (eg to damage their chitin containing coats) – part of innate immune response in mammals

—— Chitinases also control growth and moulting

—— Chitinase inhibitors have therefore also received attention as biopesticides against insects and fungi

Question 12

Give an example of a business making money from chitosan.

Answer 12

—— Primex.is Icelandic marine

biotechnology company

—— Chitosan.no

—— Norwegian chitosan manufacturer

—— Many companies in India and China

Question 13

What is the market size of chitosan?

Answer 13

—— Chitin and chitin derived products estimated to be worth £33 billion per year (sales) by 2015

—— For chitosan this figure is expected to be in the region of £10bn

—— New applications such as edible films for food preservation indicate the market will grow

Question 14

Conclusions

Answer 14

—— Chitin is a widely available marine biopolymer

—— Its unique properties allow its use in a number of industrial as well as medical applications

—— Chitin is also an important part of the marine food chain and can be digested by a number of chitinase producing marine bacteria.

Question 15

What happened in the study on wound dressing?

Answer 15

Study: Chitin membrane for wound dressing application – preparation, characterisation and toxiological evaluation.

(Singh et al, 2009)

• Chitin membranes were prepared as a wound dressing and were found to provide an effective barrier to microbial penetration and exerted a broad bacteriostatic action against gram + and – bacteria.
• Complete inhibition of a range of bacterial growth was observed in contact with the dressing
• Chitin has been shown to be useful as a wound dressing material, drug delivery vehicle and increasingly a candidate for tissue engineering – found to have an accelerating effect on the wound healing process, alongside properties of pain relief.
• In biomedical applications chitin is more favorable than chitinosan because the acetamide group present in chitin is similar to the amide linkage of a protein, making it more biocompatible than chitinosan.

Question 16

Study: Chitin membrane for wound dressing application – preparation, characterisation and toxicological evaluation.

Method

Answer 16

Method:

• Agar plates were prepared with various methods to test the growth of bacteria though or on the membrane.
• Subcutaneous and scarification tests in guinea pigs showed no significant signs of inflammation, and successfully passes a test (Finkelstein’s) on rabbits)

Question 17

Study: Chitin membrane for wound dressing application – preparation, characterisation and toxicological evaluation.

(Singh et al, 2009)

Results

Answer 17

Results

• The membrane were found to be impermeable to various bacilli and cocci strains but not others such as e.coli.
• The chitin dressings exhibited strong bacteriostatic effect on the eight bacterial strains tested and complete inhibition of bacterial growth was observed in contact with the dressing.
• No signs of inflammation were shown from the animal inflammation tests.
• Showed properties of being able to keep the wound wet, be permeable to air, stimulate damaged tissue, be removed without causing trauma – ideal properties for a dressing.

Question 18

Study: Chitin membrane for wound dressing application – preparation, characterisation and toxicological evaluation.

Critical analysis

Answer 18

Critical analysis

• Comparison between the relatively low number of 8 strains of bacteria tested and the environment.
• How soya bean caesin agar plates compare to blood tissue. The real application may be on a much larger scale with more transport opportunities for the bacteria.

Question 19

Study - prawn waste

Answer 19

Study: Utilization of prawn waste for chitinase production by the marine fungus Beauveria bassiana by solid state fermentation.

(Suresh and Chandrasekaran, 1998)

• Using a technique called solid state fermentation the bacterium Beauveria Bassiana breaks down prawn waste into chitin, with a yield of up to 248 units / g.
• This method replaces the conventional method of ocean dumping, incineration and land filling. This bioconversion of waste both the most cost-effective and environmentally friendly method. In India 60 – 80 thousand tonnes of chitinour waste are produced annually.
• Chitinase is used as antifungal agent in combination with antifungal drugs in therapy for various fungal infections.

Question 20

Study: Utilization of prawn waste for chitinase production by the marine fungus Beauveria bassiana by solid-state fermentation.

findings

Answer 20

Findings:

(Suresh and Chandrasekara, 1998)

• Moisture is a critical factor effect the hydrolytic enzyme production with a 5:1 chitinous waste to seawater ratio being most effective.
• Enrichment with NaCl increases the chitinase yield, this also show these organisms have a high tolerance to salt. Other factors such as particle size and nitrogen and phosphate enrichment effected the yield.
• The ultimate limiting factor of fungal biomass production is sporulation, indicating low substrate conversion.
• The study shows that the process is industrially feasible but economic viability has meant that I don’t think chitinous waste has been processes in this way industrially yet.

Question 21

wider reading another method of breaking down chiitin

Answer 21

Fines & Holt (2010)- discovered that cobia Rachycentron canadum are able to digest chitin due to the presence of chitinolytic enzymes. They have strong endogenous chitinolytic enzymes meaning they can break down crab and shrimp meal. This is advantageous as aquaculture facilities can be placed near crustacean processing facilities, and the cobia can feed off the waste of the crustacean. This is advantageous as it therefore reduces the cost of feed.

Question 22

Chitin scaffold in tissue engineering

Answer 22

Jakahumar et al (2011)- Chitin Scaffolds in Tissue Engineering. – Scaffolds are used in medicine for the regeneration of new tissues using healthy stem cells, most commonly in situations where bone or cartilage is damaged. The scaffold must be the correct size, shape and porosity for the new tissue to properly develop, as these factors allow cell migration, proliferation and differentiation to take place. Chitin is used due to its properties: its non-toxic, biodegradable and biocompatible. It therefore succeeds as a tissue engineering biomaterial, as it can be manipulated into different shapes and is easily processed into gel, and can be used in numerous applications. It has also been proven to enhance recovery time and reduce the likelihood of any infections.

Question 23

study - digest chitin

Answer 23

Fines & Holt (2010)- discovered that cobia Rachycentron canadum are able to digest chitin due to the presence of chitinolytic enzymes. They have strong endogenous chitinolytic enzymes meaning they can break down crab and shrimp meal. This is advantageous as aquaculture facilities can be placed near crustacean processing facilities, and the cobia can feed off the waste of the crustacean. This is advantageous as it therefore reduces the cost of feed.