Chitosan polymer chain. Molecular model of the linear polysaccharide chitosan, also known as poliglusam. This chemical is produced commercially by deacetylation of chitin. The structure is a chain of D-glucosamine (C6.H13.N.O5) and N-acetyl-D-glucosamine (C8.H15.N.O6). The chain here is mostly units of D-glucosamine, with one unit of N-acetyl-D-glucosamine at lower left (second unit from left, with a methyl [CH3] group). This polymer is used as seed treatment and a plant growth enhancer. It is also used as a fat binder. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue) and oxygen (red).