Kitosan adalah turunan kitin yang hanya dibedakan oleh gugus radikal CH3. CO- pada struktur polimernya. Kitosan merupakan senyawa kimia yang berasal dari bahan hayati kitin, suatu senyawa organik yang melimpah di alam ini setelah selulosa. Kitin ini umumnya diperoleh dari kerangka hewan invertebrata dari kelompok Arthopoda sp, Molusca sp, Coelenterata sp, Annelida sp, Nematoda sp, dan beberapa dari kelompok jamur. Selain dari kerangka hewan invertebrate, juga banyak ditemukan pada bagian insang ikan, trachea, dinding usus dan pada kulit cumi-cumi. Sebagai sumber utamanya ialah cangkang Crustaceae sp, yaitu udang, lobster, kepiting, dan hewan yang bercangkang lainnya, terutama asal laut. Sumber ini diutamakan karena bertujuan untuk memberdayakan limbah udang.
Kitosan mempunyai sifat antimikrobia melawan jamur lebih kuat dari kitin. Jika kitosan ditambahkan pada tanah, maka akan menstimulir pertumbuhan mikrobia mikrobia yang dapat mengurai jamur. Selain itu kitosan juga dapat disemprotkan langsung pada tanaman. Sifat kitin dan kitosan dapat mengikat air dan lemak.
Karena sifatnya yang dapat bereaksi dengan asam-asam seperti polifenol, maka kitosan sangat cocok untuk menurunkan kadar asam pada buah-buahan, sayuran dan ekstrak kopi. Kitosan mempunyai sifat polikationik, sehingga dapat dimanfaatkan sebagai agensia penggumpal.
Kitosan mempunyai sifat antimikrobia melawan jamur lebih kuat dari kitin. Jika kitosan ditambahkan pada tanah, maka akan menstimulir pertumbuhan mikrobia mikrobia yang dapat mengurai jamur. Selain itu kitosan juga dapat disemprotkan langsung pada tanaman. Sifat kitin dan kitosan dapat mengikat air dan lemak.
Karena sifatnya yang dapat bereaksi dengan asam-asam seperti polifenol, maka kitosan sangat cocok untuk menurunkan kadar asam pada buah-buahan, sayuran dan ekstrak kopi. Kitosan mempunyai sifat polikationik, sehingga dapat dimanfaatkan sebagai agensia penggumpal.
2. "Sumber: Wikipedia"
Chitosan is produced commercially by deacetylation of chitin , which is the structural element in the exoskeleton of crustaceans (crabs,
Manufacture and properties.
Chitosan is produced commercially by deacetylation of chitin , which is the structural element in the exoskeleton of crustaceans (crabs, shrimp, etc.) and cell walls of fungi. The degree of deacetylation (%DD) can be determined by NMR spectroscopy, and the %DD in commercial chitosans is in the range 60-100 %.
The amino group in chitosan has a pKa value of ~6.5, thus, chitosan is positively charged and soluble in acidic to neutral solution with a charge density dependent on pH and the %DA-value. This makes chitosan a bioadhesive which readily binds to negatively charged surfaces such as mucosal membranes. Chitosan enhances the transport of polar drugs across epithelial surfaces, and is biocompatible and biodegradable. Purified qualities of chitosans are available for biomedical applications.
Chitosan and its derivatives such as trimethylchitosan (where the amino group has been trimethylated) have been used in non-viral gene delivery. Trimethylchitosan, or quaternised chitosan, has been shown to transfect breast cancer cells; with increased degree of trimethylation increasing the cytotoxicity and at approximately 50% trimethylation the derivative is the most efficient at gene delivery. Oligomeric derivatives (3-6 kDa) are relatively non-toxic and have good gene delivery properties.[2]
Usage:
Agricultural & Horticultural use
Natural Biocontrol & Elicitor
In agriculture, chitosan is used primarily as a natural seed treatment and plant growth enhancer, and as a ecologically friendly biopesticide substance that boosts the innate ability of plants to defend themselves against fungal infections.The natural biocontrol active ingredient, chitin/chitosan, are found in the shells of crustaceans, such as lobsters, crabs, and shrimp, and many other organisms including insects and fungi. It is one of the most abundant bio-gradable materials in the world. Degraded molecules of chitin/chitosan exist in soil and water.
Chitosan applications for plants and crops are regulated by the EPA and the USDA National Organic Program regulates its use on organic certified farms and crops.EPA approved bio-degradable chitosan products are allowed for use outdoors and indoors on plants and crops grown commercially and by consumers. The natural biocontrol ability of chitosan should not be confused with the effects of fertilizers or pesticides upon plants or the environment. Chitosan active biopesticides represent a new tier of cost effective biological control of crops for agriculture and horticulture.
The biocontrol mode of action of chitosan elicits natural innate defense responses within plant to resist against insects, pathogens, and soil borne diseases when applied to foliage or the soil.Chitosan increases photosynthesis, promotes and enhances plant growth, stimulates nutrient uptake, increases germination and sprouting, and boosts plant vigor. When used as seed treatment or seed coating on cotton, corn, seed potatoes, soybean, sugar beet, tomato, wheat and many other seeds it elicits an innate immunity response in developing roots which destroy parasitic cyst nematodes without harming beneficial nematodes and organisms.
Agricultural applications of chitosan can reduce environmental stress due to drought and soil deficiencies, strengthen seed vitality, improve stand quality, increase yields, and reduce fruit decay of vegetables, fruits and citrus crops (see photo right). Horticultural applications of chitosan increases blooms, extends the life of cut flowers and Christmas trees.The US Forest Service has conducted research on chitosan to control pathogens in pine trees. and chitosan's ability to increase pine tree resin pitch-out flow by 40% to resist pine beetle infestation.
Chitosan has a rich history of being researched for applications in agriculture and horticulture dating back to the 1980s. By 1989 Bentech Labs patented chitosan salt solutions applied to crops for improved freeze protection or to crop seed for seed priming.Shortly thereafter Bentech's chitosan salt received the first ever biopesticide label from the EPA. Numerous other chitosan patents for plants soon followed. Chitosan applications to protect plants have been used in space as well. NASA first flew a chitosan experiment to protect adzuki beans grown aboard the space shuttle and Mir space station in 1997 (see photo left).
NASA results revealed chitosan induces increased growth (biomass) and pathogen resistance due to elevated levels of beta 1-3 glucanase enzymes within plant cells. NASA confirmed chitosan elicits the same effect in plants on earth. Over 20 years of R&D by DuPont/ConAgra Ventures (DCV) and AgriHouse Inc have gone into developing non-toxic low molecular weight chitosan polymer solutions safe enough for broad spectrum agricultural and horticultural use. In 2008, AgriHouse Inc, Denver [Berthoud], Colorado, was granted EPA natural broad spectrum elicitor status for YEA! Yield Enhancing Agent, a liquid solution containing an ultra low molecular active ingredient of 0.25% chitosan. YEA! is a next generation natural chitosan elicitor solution for agriculture and horticultural and was granted an amended label for foliar and irrigation applications by the EPA in June, 2009. A milliliter of YEA! contains over 14.4 X 10¹³ bio-active low molecular weight chitosan molecules and it is 600 times more effective than common chitosan.Given its low potential for toxicity and its abundance in the natural environment, chitosan does not harm people, pets, wildlife, or the environment when used according to label directions. Agricultural chitosan facts are located on USDA and EPA web sites.
