Index >> Applications of Microbial Interactions >> Sources of Organic Carbon

The difference in the glucose linkage between starch and cellulose makes it impossible for the starch digesting enzymes, e.g. alpha-amylase, to break down cellulose. The direct consequence of this specificity is that various organisms, including humans, cannot use cellulose to satisfy their nutritional requirement for carbohydrates.

However, some animals and insects, such as cattle, sheep, horses, termites, and caterpillars, can subsist on wood and grass, although they themselves do not produce cellulolytic enzymes. This is due to the synergistic effect of the bacteria present in their digestive tracts. These gut bacterial flora secrete the necessary cellulolytic enzymes to digest cellulose, and the hosts, in turn, provide them with a shelter as well as nutrients.

It is a complex polymer of coumaryl, coniferyl subunits. It is an aromatic ring (phenyl) with a three-carbon side chain (phenyl propanoid). Lignin is the richest source of aromatic (carbon) compounds in nature.

Fats, waxes and hydrocarbons They are carbon compounds soluble in ether. Fatty acids are components of cell membranes. They are either saturated or unsaturated (contain one or more double bonds between carbon atoms). Some of the problems associated with microbial utilisation of plant carbon include physical barriers by cell wall compounds, cutins, suberins, chitins etc. lignin which slows the rate of decomposition by microbes, and the microbicidal properties of some plants.