The following points highlight the top ten uses of microbes. The uses are: 1. Production of Antibiotics 2. Production of Dairy Products 3. Production of Alcoholic Beverages 4. Production of Bread 5. Production of Food Yeast 6. Production of Organic Acids 7. Production of Vitamins 8. Production of Enzymes 9. Production of Steroids 10. Production of Dextran.
Use # 1. Production of Antibiotics:
Antibiotics are metabolic products of several harmless microorganisms. They are used to kill various pathogenic microorganisms, so helpful in treating many diseases. The important antibiotics currently used in medicines are Penicillin, Streptomycin Bacitracin, Chloromycin, Chlorotetracycline, Tetracycline, Neomycin terramycin, Auromycin, Puromycin, Haymycin and Erythromycin.
Besides their use in the treatment of human diseases, certain antibiotics are used as food preservatives. Some antibiotics are found use in the control of plant pathogens. For example, Griseofulvin, which is not suitable to man is used in the control of bean rust.
Use # 2. Production of Dairy Products:
Microorganisms are useful in the production of cheese, butter milk and other dairy products.
(a) Cheese:
This is produced from milk and is dependent upon the activity of microorganisms like Streptococcus lactis, S. cremoris, Leuconostoc citrivorum etc. The manufacture of cheese consists of curdling the milk by addition of lactic acid bacteria processing of curd to remove moisture, salting and ripening.
During ripening, the microorganism induce proteolytic as well as lipolytic activity. The ripening period of cheese varies from 1 to 16 months. Cheese is a very nutritious food. Its composition is 20 – 35% protein, 20 – 30% fat and a small quantity of minerals.
(b) Buttermilk:
The microorganisms used to produce buttermilk are streptococcus lactis or S. cremoris and Leuconostoc citrivorum or L. dextranum. The latter produces volatile acids and neutral products which give the buttermilk its typical flavour.
(c) Butter:
Butter is made by churning the cream which has been soured by lactic acid bacteria.
Use # 3. Production of Alcoholic Beverages:
Alcholic beverages are produced by the fermentation of sugars by yeasts.
The yeast used is normally Saccharomyces cerevisae.
Some common alcoholic beverages are:
(a) Vinegar:
The manufacture of vinegar involves alcoholic fermentation of substrate by yeast. After the fermentation is complete, yeast pulp and other sediments are removed by settling. The supernant is fermented by acetic bacteria, Acetobacter sp. The optimum alcoholic concentration is 10 – 13%.
(b) Beer:
It is prepared from barley malt. Barley malt is converted in to sugar by the enzymatic action of Asper gillus oryzae. In next step maltose is converted into alcohol.
(c) Wine:
It is manufactured by the action of yeast, Saccharomyces ellipsoideus on the grape juice.
(d) Rum:
It is manufactured by fermentation of molasses with the help of yeast S. cerevisae.
Use # 4. Production of Bread making:
Selected strains of S. cerevisae are mixed in the dough. Fermentation results in the production of carbon dioxide which causes the dough to rise (leavening) and brings about a desired change in the texture and flavour. The quality of the bread depends upon the strain of yeast, selection of raw materials and incubation conditions.
Use # 5. Production of Food Yeast:
Yeast is used as a very nourishing material and is often taken as a food supplement Torulopsis utilis is a food yeast cultured and marketed commercially. Yeast is a good source of Vitamin B complex and also rich in proteins. Yeast is a byproduct of brewing industry, and is also cultured in a medium containing molasses, cane sugar, potatoes of other fermentable carbohydrates.
Use # 6. Production of Organic Acids:
Some of the common organic acids are produced commercially by microorganisms:
(a) Acetic acid:
It is the vinegar obtained by the fermentation of fruits and sugar containing syrups by Acetobacter sp.
(b) Citric acid:
It is an important industrial product obtained through Aspergillus niger. Citric acid is used in medicine flavouring extracts, food and candies, manufacture of ink, dyeing etc.
(c) Fumeric acid:
This is produced through Rhizopus nigricans.
(d) Gluconic acid:
It is obtained by growing Aspergillus niger or Pencillium purpurogenum in a medium containing corn sugar with ammonium phosphate, magnesium sulphate and calcium carbonate. It is used to produce calcium gluconate, a source of calcium in feeding infants and pregnant women.
(e) Itaconic acid:
It is obtained by growing A. terreus in a medium.
(f) Kojic acid:
It is produced by A. flavus when grown in a medium with sugar plus minerals.
(g) Lactic acid:
It is produced by Lactobacillus delbruck L. bulgaricus and Streptococcus lactis from corn starch or potatoesLactic acid is used in confectionery extracts, fruit juices, essences pickles, canned vegetables, fish products etc.
Use # 7. Production of Vitamins:
Microorganisms are useful to mankind as they produce many vitamins. Yeasts manufacture vitamin B. complex. For commercial production of B12, Cobalamin, bacteria and actinomycetes like Streptomyces olivaceus and Bacillus megatherium are used. Riboflavin (B2) is produced by a number of microorganisms like Ashbya gossypii Eremothecium ashbyii and Closteridium bytyricum. L-Sorbose, a precursor of vitamin C, ascorbic acid, is produced by different species of Acetobacter from D-Sorbitol by biological dehydrogenation.
Use # 8. Production of Enzymes:
Many enzymes are synthesized by microorganisms. They are commercially not important as their separation and purification involved high cost.
Some of the microbial enzymes useful to man are:
(i) Amylases:
Produced from Bacillus subtilis, Aspergillus niger and Rhizopus oryzae.
(ii) Dextran sucrase:
Produced from Leuconostoc meseniteroides.
(iii) Lactase:
Produced by Saccharomyces cerevisae.
(iv) Lipase:
Obtained from Candida lipolytica.
(v) Pectinase:
Manufactured from Byssochlamys fulvo.
(vi) Proteases and peptidases:
Obtained from Bacillus subtilis and Mortierella renispora.
(vii) Invertase:
Obtained from S. cerevisiae.
(viii) Penicillinase:
Produced from Actinomyces candidus.
Use # 9. Production of Steroids:
Microbes like Actinomycetes, Aspergillus, Streptomyces and Gliocladium are used to produce different steroids from progesterone by microbial transformations. Steroids manufactured by combination of chemical and microbial methods are finding wide use in family planning and in treatment of diseases.
Use # 10. Production of Dextrans:
They are polymers of D-glucose and also are polyglucosans. Fermentation process with the help of Leuconostoc meseniteroides is used in their production. Dextrans with different molecular weights have clinical use.
(i) Soil Microbiology:
Microorganisms are beneficial in increasing the fertility of soil. Nitrogen fixing bacterium Rhizobium helps in fixing atmospheric nitrogen in the root nodules of leguminous plants. Different soil bacteria convert organic substances into inorganic compounds, releasing nutrients to growing plants. They also decompose dead plants and animals.
(ii) Coal and Petroleum Microbiology:
Microbes play an important role in the formation of coal and petroleum. Bacteria oxidizes the organic matter to compounds similar to petroleum. Some important bacteria associated with petroleum formation are Clostridium perfringers, Vibrio desulphuricans and Beggiatoa alba.
(iii) Sewage Microbiology:
Many microorganisms are useful to purify domestic wastes. They are responsible for digestion and oxidation of organic materials. They destroy the pathogenic types.
(iv) Bioassay:
Microorganisms are employed in biological studies. They can be experimented to study the effect of different drugs. In few cases, they are utilized to test organisms to detect the presence of unknown chemical substances. For instance, the presence of traces of copper can be detected by growing Aspergillus niger.
(v) Biological Pest Control:
Bacteria and viruses can cause epidemics among different insect pests without destroying beneficial insects.
(vi) Biological Warfare:
Microbes or their toxic products can be used in biological warfare. Their release through air or water may spread different diseases and cause damage to man, domestic animals and plants.