Substrates Used For Production of SCP
A variety of substrates are used for SCP production. However, availability of necessary substrates is of considerable biological and economic importance for the production of SCP. Algae which contain chlorophylls, do not require organic wastes. They use free energy from sunlight and carbondioxide from air, while bacteria (except photoautotrops) and fungi require organic wastes, as they do not contain chlorophylls (Roth, 1982).
The major components of substrates are the raw materials which contain sugars (sugarcane, sugarbeet and their processed products), starch (grains, tapioca, potato, and their by-products), lignocelluloses from woody plants and herbs having residues with nitrogen and phosphorous contents and other raw materials (whey and refuses from processed food). Organic wastes are also generated by certain industries and are rich in aromatic compounds or hydrocarbons (Bull et al,
1983). Recent price-increase in petroleum and refined petroleum products has made hydrocarbons and chemicals derived from them (such as methanol and ethanol) less attractive as raw materials for SCP production that renewable sources such as agricultural wastes or by-products. A detailed account of these wastes is given in Wastes as renewable source of energy