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Industrial microbiology includes the use of microorganisms to manufacture food, drugs and other industrial products of economic importance in large quantities. The microorganisms used in industrial microbiology include naturally-occurring microbes, genetically modified organisms (GMOs), and laboratory selected mutants or strains whose genetic makeup have been genetically engineered and/or improved to produce certain metabolites in large amounts and under controlled environmental conditions. Microorganisms including moulds, bacteria, actinomycetes, yeasts and viruses play tremendous roles in many industrial processes including those that have to do with the production of medicines or drugs, food, enzymes, detergents and other metabolites of industrial importance as aforementioned. Microbes are widely used in large-scale industrial fermentation processes; and these organisms produce metabolites that make these fermentation processes possible.

Microorganisms are used in the production of many substances or products of economic importance such as biofertilizers, ethanol, wine, yoghurt, bread, citric acid, industrial enzymes, antibiotics, vaccines, toxoids, alkaloids, steroids, sterols, fermented foods, sauerkraut, single cell proteins (SCPs), microbial insecticides, butanol, lactic acid, amino acids, and riboflavin. Microorganisms are of immense importance in bioremediation activities – in which microbes are used to clean up the environment especially in places where there is oil spillage and other biodegradable contaminants. Microbes are also employed in the biotransformation of several chemicals to facilitate the reduction of environmental pollution. They can be used to create biofertilizers – which increases the fertility of the soil and protects the environment from the adverse effects of chemical fertilizers.

Biofertilizers consist of living, microbial inoculants such as Rhizobium inoculants that are added to the soil and are known to increase plant growth by providing plants with increased amounts of nutrients. Rhizobium inoculants when added to the soil help to form nitrogen-fixing nodules with leguminous plants; and this increases the amount of nitrogen required for optimal plant growth because nitrogen is a key element in the nutrition of living things. Nitrogen provides the bases for enzyme synthesis and protein production. The ability to carry out biological nitrogen fixation is only found in bacteria and blue green algae; and the ability of bacteria such as Rhizobium species to fix nitrogen in the free living state especially in the soil (when the organism form a symbiotic association with leguminous plants) helps to improve the nitrogen status of the soil. Chemical fixation of nitrogen is also possible; and this principle is applied in the production of nitrogenous chemical fertilizers which are applied to the soil to replenish nitrogen lost from the soil by plants and other agricultural or natural activities. Medically, microbes including bacteria, viruses, fungi and actinomycetes have been exploited in the production of medicines (drugs), vaccines, and other biopharmaceuticals such as insulin – which is used to treat diabetes. The production of most economically-significant product such as beer and wine go through the process of fermentation before the extraction of the final (end) product of fermentation; and these processes are mainly activated by microbes and/or their enzymes. If these microbes fail to metabolize or utilize the nutrients provided in their growth medium or fermenter, the primary metabolites (which are central to the growth and the reproduction of the organism will not be produced); and the secondary metabolites (which are of immense economic importance to man, plants, animals and the environment) will not be produced at optimal amounts required for further processing. Primary metabolites and secondary metabolites are often used in industrial microbiology for the production of food, amino acids, vaccines, biopharmaceuticals, and antibiotics.

Primary metabolites are produced during the growth of an organism especially at the exponential phase of growth of the organism. They are involved in the growth, development and reproduction of microorganisms; and they act as key components in maintaining the normal physiological and metabolic processes of the organism. Examples of primary metabolites are alcohol, vitamins and essential amino acids.

Secondary metabolites are produced at the end of growth of the organism especially during the stationary phase of growth when the organism is resting and is not actively growing. They are not involved in the growth, development and reproduction of the organism; and they are usually organic compounds that are produced through the modification of primary metabolites. Secondary metabolites provide defensive function and they have tremendous economic importance; and they play no role in maintaining the physiological and metabolic processes of the organism. Examples of secondary metabolites include: antibiotics steroids and enzymes. Microorganisms including bacteria, fungi, and actinomycetes drive fermentation processes and it is important that they continue to produce metabolites that encourage their optimal growth during fermentation processes. These organisms are important in fermentation processes because of the metabolites that they produce during and after their growth or development.

The major role of microorganisms including bacteria, yeasts, viruses, moulds and actinomycetes in fermentation processes is to convert or breakdown large substrates (macromolecules) to economically important end-products. As the organism is growing in the fermenter or fermentation vessel, it produces primary metabolites- which it uses to maximize the available substrate or nutrient in the growth vessel (fermenter). These primary metabolites are primarily utilized by the organism to manufacturer its secondary metabolites such as antibiotics that are of great economic importance. Most fermentation processes are activated by microorganism or by the enzymes that they produce; and these organisms act on their own or in collaboration with other microbes. The term fermentation means different things to different persons or disciplines. However, fermentation here is defined as a metabolic process that converts sugars (substrates) to alcohol, acids and gases (e.g. CO2). It can occur both in the presence of oxygen and in the absence of oxygen. But most fermentation processes occur in the absence of oxygen.

Fermentation can also occur when organisms including moulds, bacteria actinomycetes and yeasts consume organic substrate molecules as part of their own metabolic processes; and thus produce metabolites of substances that are of economic importance in the process. When spoilage microbes grow in food they cause spoilage and food borne diseases when such contaminated food is consumed. However some fermentation processes are highly desirable since they lead to the production of important molecules or substances like alcohol, acids and gases and other microbial by-products that are significant in food production. Yoghurt, SCPs, bread, cheese, sauerkraut, wine and beer are some examples of food produced through fermentation processes that are mainly spurred by microbial activity and/or their enzymatic reactions. Fermentation posses several benefits – which is why it is employed in many industrial processes for the production of economically-significant products. 

Further reading

Bushell M.E (1998). Application   of   the   principles   of   industrial   microbiology   to   biotechnology (ed. Wiseman, A.) Chapman and Hall, New York.

Byong H. Lee (2015). Fundamentals of Food Biotechnology. Second edition. Wiley-Blackwell, New Jersey, United States.

Frazier W.C, Westhoff D.C and Vanitha N.M (2014). Food Microbiology. Fifth edition. McGraw-Hill Education (India) Private Limited, New Delhi, India.

Jay J.M (2005). Modern Food Microbiology. Fourth edition. Chapman and Hall Inc, New York, USA.

Bushell M.E (1998). Application   of   the   principles   of   industrial   microbiology   to   biotechnology (ed. Wiseman, A.) Chapman and Hall, New York.

Farida A.A (2012). Dairy Microbiology. First edition. Random Publications. New Delhi, India.

Nduka Okafor (2007). Modern industrial microbiology and biotechnology. First edition. Science Publishers, New Hampshire, USA.

Roberts D and Greenwood M (2003). Practical Food Microbiology. Third edition. Blackwell publishing Inc, USA.

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