MICROBES IN INDUSTRIAL PRODUCTS

Fermentive activity of microbes is used industrially to obtain a number of products. Production on an industrial scale, requires growing microbes in very large vessels called fermentors. The two common ones are alcoholic fermentation and antibiotics.

Fermented Beverages/Alcoholic Fermentation

Yeast species used in alcoholic fermentation are Saccharomyces cerevisiae (Brewer's Yeast), S. ellipsoidens (Wine Yeast), S. sake (Sake Yeast) and S. pireformis (Ginger Beer/Ale Yeast).

The nutrient medium is barley malt for beer, fermented rye malt for gin, fermented rice for sake, cashew-apple for fenny, potato for vodka, fermented cereals for whisky, fermented molasses for rum and fermented juices for wines and brandy.

Wine and beer are produced without distillation, whereas whisky (50% alcohol), brandy (65-70% alcohol), rum (40% alcohol) and gin about (40% alcohol) are produced by distillation of fermented broth.

Antibiotics (means against life in Greek)

An antibiotic is a substance produced by a microorganism, which in low concentration inhibits the growth and metabolic activity of pathogenic organisms without harming the host.

This is among the most significant discoveries of twentieth century.

First antibiotic is generally associated with the name of Alexander Flemming (1928) when he discovered Penicillin from Penicillium notatum.

The antibiotic was however, commercially extracted by efforts of Ernst Chain and Howard Florey. The chemical was extensively used in treating wounded American soldiers in world war II. Flemming, Chain and Florey were awarded Nobel Prize in 1945. Bulk of antibiotics are obtained from three groups of microorganism i.e., Eubacteria, actinomycetes and fungi.

Concept Builder

Name of the antibiotics :

1. From Eubacteria

(i) Bacitracin Bacillus licheniformis

(ii) Subtiiin Bacillus subtilis

(iii) Polymyxin Bacillus polymyxa

(iv) Gramicidin Bacillus brevis

2. From Actinomycetes

(i) Chlorotetracycline or aureomycin Streptomyces aureofaciens

(or tetracycline)

(ii) Chloramphenicol or chloromycetin Streptomyces venezuelae and S. lavendulae

(iii) Erythromycin Streptomyces erythreus

(iv) Neomycin Streptomyces fradiae

(v) Oxytetracycline or terramycin Streptomyces rimosus

(vi) Streptomycin Streptomyces griseus

Antibiotics have greatly improved our capacity to treat deadly diseases like plague, whooping cough, diphtheria, leprosy etc. So with reference to human beings these are pro-life.

Chemicals, Enzymes and Other Bioactive Molecules

Bioactive molecules are those molecules which are functional in living systems or can interact with their components. A number of them are obtained from microbes like organic acids, enzymes, cyclosporin A and statins.

(A) Organic Acids

Certain microbes have the ability to convert carbohydrates into organic acids, this capability of microorganisms is applied in the industrial production of some commercially important organic acids. A few very important organic acids are as follows.

1. Acetic acid : It is prepared from fermented alcohols with the help of acetic acid bacteria, Acetobacter aceti. Alcoholic fermentation by yeast is anaerobic process, but the conversion of alcohol to acetic acid is aerobic one. It is used for the prepration of vinegar. It is also used in pharmaceuticals, colouring agents, insecticides and plastic industries.

2. Citric acid : It is obtained through the fermentation carried out by fungi Aspergillus niger and Mucor species on sugary syrups. Yeast Candida lipolytica can also be employed, provided its nutrient medium is made deficient of iron and manganese. Citric acid is employed in dyeing, engraving, medicines, inks, flavouring and preservation of food and candies.

3. Gluconic acid : The acid is prepared by the activity of Aspergillus niger and Penicillium chtysogenum. Gluconate is used widely as a source of calcium for infants, cows and lactating mothers.

4. Lactic acid : It was first acid to be produced by industrial fermentation. It is commercially produced from fermentable carbohydrates such as corn and potato starch, molasses and whey by using the bacteria - Lactobacillus bulgaricus and L. delbrueckii.

(B) Enzymes

Hardly 1.0-1.5% of the total known enzymes are employed in industry and medicine.

1. Pectinases : They are obtained from fungi grown on pectin containing medium. Examples are Aspergillus niget, Byssochlamys fulvo. They are used in enhancing juice extraction and clearing of juices.

2. Proteases : Proteases are obtained from Mortierella renispora, Aspergillus and Bacillus species, used in detergents to remove proteinaceous spots. Bottled juices are also clarified using proteases and pectinase.

3. Amylases : They degrade starch. Amylases are obtained from Aspergillus, Rhizopus and Bacillus species.

Amylases, glucoamylases and glucoisomerases are employed in conversion of corn starch into fructose rich corn syrup.

4. Streptokinase (Tissue Plasminogen Activator or TPA) : It is an enzyme obtained from the cultures of some haemolytic Streptococci. It has fibrinolytic effect, used to dissolve blood clots in heart patients.

(C) Cyclosporin A

It is an eleven membered cyclic oligopeptide obtained through fermentive activity of fungus Trichoderma polysporum.

It has antifungal and anti-inflammatory properties. It is used as an immunosuppressive agent in organ-transplant patients.

(D) Statins

They are products of fermentation activity of yeast Monascus purpureus which resemble mevalonate and is competitive inhibitor of -hydroxy--methylglutaryl CoA reductase or HMG COA reductase.

This competitively inhibits cholesterol synthesis. It is used as cholesterol lowering agent.