MICROBES IN INDUSTRIAL PRODUCTS
Fermented Beverages
- Microbes, particularly yeasts like Saccharomyces cerevisiae (brewer’s yeast), are used for the fermentation of raw materials such as malted cereals and fruit juices to produce alcoholic beverages like wine, beer, whisky, brandy, and rum.
- The metabolic reactions of yeast result in the production of ethanol during fermentation.
It’s fascinating how Saccharomyces cerevisiae, or brewer’s yeast, has been a faithful companion in the production of various alcoholic beverages throughout history. The process of fermentation, where yeast converts sugars into alcohol and carbon dioxide, is the magic behind these drinks.
Beer and Wine:
- In beer and wine production, the fermented broth is not subjected to distillation. Instead, the naturally fermented liquid is typically filtered and then packaged for consumption.
- Beer is made from malted cereals, usually barley, and undergoes a brewing process that includes fermentation.
- Wine is produced by fermenting fruit juices, often from grapes, and allowing the yeast to work its magic.
Whisky, Brandy, and Rum:
- For spirits like whisky, brandy, and rum, an additional step of distillation is involved.
- After fermentation, the liquid undergoes distillation, a process that separates alcohol from the water and other components, concentrating the alcohol content.
- The distilled product is then aged in barrels, contributing to the distinct flavors and characteristics of each spirit.
Do you recollect the metabolic reactions, which result in the production of ethanol by yeast?
The metabolic process that leads to the production of ethanol by yeast, such as Saccharomyces cerevisiae, is called alcoholic fermentation. Here’s a brief overview of the key metabolic reactions involved:
Glycolysis:
- The process begins with glycolysis, where a glucose molecule (a type of sugar) is broken down into two molecules of pyruvate. This occurs in the cytoplasm of the yeast cell.
- Glycolysis yields a small amount of energy in the form of ATP and NADH.
Decarboxylation:
- The two molecules of pyruvate generated in glycolysis undergo decarboxylation. One carbon is removed from each pyruvate, resulting in the formation of acetaldehyde and releasing carbon dioxide.
Ethanol Formation:
- Acetaldehyde, the product of decarboxylation, is then reduced by NADH to form ethanol.
- This reduction step regenerates NAD+, which is crucial for sustaining glycolysis.
The overall chemical equation for alcoholic fermentation by yeast can be represented as follows:
Glucose → 2 Ethanol + 2 Carbon Dioxide + Energy
Antibiotics
Antibiotics: A 20th Century Milestone
- Definition: Chemical substances combating disease-causing organisms.
- Etymology: “Anti” (Greek: against) + “Bio” (life) = Against life in the microbial context; Pro-life for humans.
Penicillin’s Chance Discovery
- Observer: Alexander Fleming
- Scenario: Mold hindering Staphylococci growth in unwashed culture plates.
- Identification: Mold – Penicillium notatum.
- Acknowledgment: Full antibiotic potential recognized later by Ernest Chain and Howard Florey.
Impact during World War II
- Application: Extensively used to treat wounded American soldiers.
- Recognition: Nobel Prize in 1945 for Fleming, Chain, and Florey.
Besides Penicillin, several other antibiotics have been discovered and are widely used. Here are a few examples:
Streptomycin: Discovered by Selman Waksman and Albert Schatz, it was the first effective treatment for tuberculosis. Streptomycin is produced by the bacterium Streptomyces griseus.
Tetracycline: This broad-spectrum antibiotic is effective against a wide range of bacteria. It is produced by various species of Streptomyces bacteria.
Chloramphenicol: Initially extracted from Streptomyces venezuelae, this antibiotic is now synthesized chemically. It has been used to treat a variety of bacterial infections.
Erythromycin: Produced by the bacterium Saccharopolyspora erythraea, this antibiotic is commonly used for respiratory tract infections and skin infections.
Cephalosporins (e.g., Cephalexin): These antibiotics are produced by fungi of the genus Cephalosporium. They are effective against a broad spectrum of bacteria.
Vancomycin: Originally isolated from the bacterium Streptomyces orientalis, it is effective against Gram-positive bacteria.
Amoxicillin: A derivative of Penicillin, it is effective against a wide range of bacteria. Amoxicillin is semi-synthetic, meaning it is chemically modified for enhanced efficacy.
Chemicals, Enzymes and other Bioactive Molecules
Microbial Role in Chemical Production:
- Organic Acids:
- Citric Acid: Produced by Aspergillus niger (fungus).
- Acetic Acid: Produced by Acetobacter aceti (bacterium).
- Butyric Acid: Produced by Clostridium butylicum (bacterium).
- Lactic Acid: Produced by Lactobacillus (bacterium).
- Alcohol Production:
- Ethanol: Commercially produced using Saccharomyces cerevisiae (yeast).
- Organic Acids:
Microbes in Enzyme Production:
- Lipases: Used in detergent formulations for oil stain removal.
Juice Clarification:
- Pectinases and Proteases: Utilized to clarify bottled fruit juices.
Medical Applications:
- Streptokinase: Produced by Streptococcus (bacterium) and genetically modified. Used as a ‘clot buster’ for myocardial infarction patients.
- Cyclosporin A: Immunossuppressive agent in organ-transplant patients. Produced by Trichoderma polysporum (fungus).
- Statins: Produced by Monascus purpureus (yeast) and commercialized as blood-cholesterol lowering agents. Inhibits cholesterol synthesis enzyme.
