Cellulose is an organic compound with the formula (C6H10O5) n, a polysaccharide consisting of a linear chain of several hundred to many thousands of beta(1-4) linked D-glucose units. Cellulose is an important structural component of the primary sell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms.
Cellulose is the most abundant organic polymer on Earth. The cellulose content of cotton fiber is 90%, that of wood is 40–50% and that of dried hemp is approximately 45%. Cellulose is mainly used to produce paperboard and papaer. Smaller quantities are converted into a wide variety of derivative products such as cellophane and rayon. Conversion of cellulose from energy crops into biofuels such as cellulosic ethanol is under investigation as an alternative fuel source.
Cellulose for industrial use is mainly obtained from wood pulp and cotton. Some animals, particularly ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts, such as Trichonympha. In humans, cellulose acts as a hydrophilic bulking agent for feces and is often referred to as a "dietary fiber".