8 – Fungi and Biotechnology
This chapter opens with a discussion of fungi and their biotechnological applications in enzymes, alcoholic beverage, mushroom, single cell protein, yeast biomass, fermented products, agrochemicals, citric acid, vitamins, antibiotics, and pharmaceutical drugs industries. Fermentation technology is concerned with large-scale culture of microorganisms in fermenters, and the recovery of useful products contained within the microbial cells or the surrounding medium. Research and laboratory activities associated with fermentation processes include preliminary investigations, scale up, culture preservations and inoculum preparations. For successful fermentation, fungus must behave in a consistent, predictable manner, giving similar growth rates and metabolite yields in successive fermentations. Industrial fermentations are carried out in stirred tank fermenters. Fungi can be grown in the laboratory either by batch culture or continuous culture. Many fungi produce extracellular enzymes that enable them to break down polysaccharides and proteins into sugars and amino acids that can be assimilated easily. Aspergillus is the most important fungus for commercial enzyme production. If fungal strain produces a small amount of a metabolite of interest, then a program of mutation and strain selection can increase the yield of the metabolite. A fungal strain for use in fermentations should be genetically stable, except when treated with mutagenic agents. The bacterium, Escherichia coli, was the first host for gene cloning, and also the first microbe to be used for the commercial production of mammalian proteins. Knowledge obtained by the application of gene cloning in basic mycological research is likely to have important practical applications.