BY: Reddy Sailaja M (MSIWM030)
Microorganisms are minute creatures from time immemorial and omnipresent in all kinds of ecosystems on earth. Microorganisms are of different types: Bacteria, Fungi, Protozoa, Algae and Virus. These are not visible through naked eye and require microscope for their structural and functional evaluation.
Industrial microbiology deals with the application of various microorganisms for industrial processes that are beneficial to mankind.
Characteristics of industrially important microorganisms include:
- Non pathogenic and non-contagious
- Easy and rapid growth on industrial scale
- Need of inexpensive medium for culture and growth
- Production of spores
- Easy inoculation
- Desired product should be produced rapidly on large scale
- capability to genetic manipulation, if required
Major industrial products produced by microorganisms:
- Pharmaceutical drugs
- Organic acids and solvents
- Dairy products
- Amino acids
Figure 1: Major applications of microorganisms
Yeast species was widely used from thousands of years to produce beverages like wine, brandy, whiskey etc. Yeasts fall under kingdom Fungi and are eukaryotic, single celled organisms. Yeasts species, Saccharomyces cerevisiae was allowed to grow on malted cereals and fruit juices to produce ethyl alcohol.
Beyond yeast, bacteria – Acetobacter, Lactobacsp. B. bucheri, etc and fungi – Pichia fermentans, Cyberlindnera mrakii etc are usually used in wine production
Discovery of Penicillin, an antibiotic by Alexander Fleming in 1928 is a significant step in medical microbiology history in the 20th century. Antibiotic is a bioactive substance produced by a microorganism that has the ability to either inhibit the growth or kill the other microorganism. Fungi are the main source of antibiotics.
Fungi of Actinomycetes group produce antibiotics like tetracyclin, streptomycin, actinomycin D etc. While, antibiotics like Penicillin, Cephalosporin etc are produced by filamentous fungi.
Organic acids and solvents:
Organic acids and solvents are produced from the microorganisms mainly for the pharmaceutical and other industrial needs. These compounds can be produced either from glucose or in the form of end products from pyruvate or ethanol.
Microorganisms that produce organic acids include:
Aspergillus niger – Citric acid
Acetobacter aceti – Acetic acid
Lactobacillus – Lactic acid
Salmonella – Formic acid
Escherichia coli – Butric acid and malic acid
Acetobacter xylinum – Ascorbic acid
Enzymes, also called biological catalysts occur naturally in the living system and regulate biochemical reactions. As enzymes have wide applicability in both medical and non-medical fields, microorganisms are genetically modified to produce industrially important enzymes. Amylase was the first industrial enzyme to be produced in the year 1896. Amylase has the ability to regulate indigestion and other digestive system related disorders.
Enzymes are widely used in food preservation, food processing, leather and paper industries, detergents and scientific research and development sectors like molecular biology.
|Microorganism||Substrate for growth||Enzyme produced||Applications|
|Aspergillus niger, Penicillium sp.||Pectin||Pectinase||Alcohol production, clarification of fruit juices|
|Saccharomyces diastaticus||Starch||Amylase||Alcohol production, starch removal glucose syrups production|
|Bacillus sp.||Proteins||Protease||Bread, baked foods, waffles production|
|Aspergillus sp.||Lipids||Lipase||Food and aroma enhancement, biofuel degradation|
|Cellulomonas sp.||Cellulose||Cellulase||Alcohol and glucose production|
|Streptomyces sp.||Xylan||Xylanase||Paper production, biofuel production|
|Actinomyces, Streptomyces sp.||Chitin||Chitinase||Food additive, therapeutic agent, antifungal and antitumor|
Table 1: Enzymatic application of microorganisms
Amino acids are building blocks of proteins and have high demand as supplements in food and nutraceutical industries. These are also used as supplements in bakery and packed foods. Microorganisms utilize amino acids for their metabolism and growth. Microorganisms are stimulated to produce extra amino acids, such that the extra amino acids are excreted into the surrounding medium.
Lysin and glutamic acid are the prime amino acid supplements in the preparation of bread and other nutritional supplements. Glutamic acid in the form of Monosodium Glutamate is used as flavor enhancing compound in the packed foods.
Glutamic acid is being produced from Corynebacterium gluatmicum. Corynebacterium sp. also used in:
- Steroid conversion – an important process in the development of pharmaceutical products.
- Hydrocarbon degradation – breakdown of plastic and oils for environmental protection.
Other amino acid producing bacteria include:
L-alanine – Corynebacterium dismutans, Pseudomonas dacunhae, Escherichia coli
L-arginine – Serratia marcescens, Bacillus subtilis
L-aspartic acid – Escherichia coli
Vitamins are critical for vital functions and a healthy life. As the human body unable to synthesize these compounds, it is necessary to be supplied in the diet in small amounts. Vegetables and meat are sources of vitamins.
Microorganisms are grown in bulk quantities for the commercial production of vitamins like – thiamine, riboflavin, folic acid, vitamin B12, ascorbic acid, beta-carotene etc.
Some microorganisms that produce vitamins include:
Beta-carotene – Blakeslea trispora, Phycomyces blakesleeanus
Riboflavin – Mycocandida riboflavin, Candida flareri, Clostridium buytilicum
Vitamin B12 – Pseudomonas denitrificans, Bacillus megaterium, Propionibacterium freudenreichii.
Trichoderma polysporum produces ‘Cyclosporin A’ which is used as immunosuppressive agent during organ transplantation. Moscus purpureus produces ‘Statins’ that has the ability to reduce blood cholesterol levels.
Single cell proteins:
Microorganisms that are rich in protein content can be used as protein supplements for human and domestic applications and are called single cell protein (SCP).
Algal species, Spirulina is the most popular SCP being produced commercially as a protein supplement.
Other SCP producing microorganisms include:
Bacteria – Pseudomonas fluorescens, Lactobacillus, B.megaterium
Algae – Chlorella pyronoidosa, Chondrus crispus
Fungi – Aspergillus fumigates, A. niger, Rhizopus cyclopium
Yeast – S.cerevisae, C.tropicalis, C.utilis
Apart from the above applications, microorganisms have major applications in vaccine production, biofuel production and in treatment of malnutrition.