Microbes are widely used in large-scale industrial processes, not only in the production of a variety of metabolites, such as ethanol, butanol, lactic acid and riboflavin, but also in the biotransformation of several chemicals to facilitate the reduction of environmental pollution. For instance, microbes can be used to create biofertilizers or to reduce metal pollutants. Finally, microbes can be used to produce certain non-microbial products, such as insulin.
The ethanol that microbes produce is widely used as a solvent, extractant and antifreeze. As well, it forms the base for many dyes, lubricants, detergents, pesticides, resins, explosives, plasticizers and synthetic fibers. N-butanol, also produced by microbes, is useful in the manufacturing of plasticizers, brake fluids, extractants and petrol additives. Glycerol is widely used in both medicines and the food industry, while mannitol is used in research and butanol is used as a solvent and in explosives.
Metal Leaching and Protection
Many bacteria thrive by reducing Fe (III), ferric iron, to Fe (II), ferrous iron, and Mn (VI) to Mn (II). Thus, certain bacteria can be used to leach Fe(III) and Mn(VI) metals from some soils and sediments and to form a range of reduced materials, which can include magnetite, siderite and rhodochorsite. This ability can result in a change in sediment structure, the potential to control water flow in aquifiers, and the potential of producing biomaterials of commercial value, such as magnetite.
Bio-fertilizers consist of living, microbial inoculants that are added to the soil and are known to increase plant growth by providing plants with increased amounts of nutrients. Commonly used bio-fertilizers include phosphate-solubilizing nitrants, which solubilize bound phosphates and make them available to plants, resulting in improved growth and yield. Mycorrhizae, referring to fungi associated with plant roots, is often critical to adequate nutrient uptake and plant survival in natural ecosystems. Azopirrilum bacteria stimulate plant growth through nitrogen fixation and production of growth substances.
Using Microbes to Produce Insulin
Genetically engineered microbes produce insulin in a pure form that is less likely to cause allergic reactions than insulin from the pancreas of slaughtered cows and pigs. Genetically engineered bacteria are grown in large, stainless steel vessels that contain all the nutrients needed for growth; when fermentation is complete, the bacteria are harvested and broken open to obtain the insulin that they have produced. Equipment is kept sterile at all times to prevent the bacteria from becoming contaminated.