Industrial Microbiology: Fermentation and Enzyme Production

Bread Fabrication via Yeast Fermentation

Bread is produced through fermentation by the yeast Saccharomyces cerevisiae, which generates ethanol (alcoholic fermentation). The ethanol evaporates during cooking, while carbon dioxide creates tiny bubbles that result in the typical spongy texture of bread. The yeast dies due to the heat.

Wine and Beer Manufacturing

This process also utilizes Saccharomyces cerevisiae for alcoholic fermentation. In the case of wine, yeast is found naturally on the skin of grapes. Beer production requires a series of steps:

• Malting: Roasting germinated barley seeds (malt).
• Brewing: Addition of hops to the fermentation product.

Cheese Fabrication

Cheese is produced through fermentation by lactic acid bacteria (e.g., Lactobacillus, Lactococcus). The process involves several steps:

1. Mixing milk with rennet (an enzyme produced in the stomach of ruminants).
2. Milk protein precipitates into a solid phase, curd, and a liquid phase, whey.
3. Filtration and addition of salt.
4. Ripening of cheese by other microorganisms (e.g., Micrococcus, Propionibacterium, Penicillium).

Chemical Industry Applications

Organochemicals used by industry are produced by microorganisms from inexpensive substrates like cellulose and starch.

Industrial Enzymes

Commonly used enzymes include:

• Proteases, amylases, and lipases: Bioactive detergents.
• Renin: Cheesemaking.
• Amylases and glucoamylases: Production of sweeteners.
• Dihydrofolate reductase (Lactobacillus casei): Anticancer applications.

Enzymes are typically immobilized to increase stability through:

• Polymerization of the enzyme.
• Binding to an inert carrier molecule.
• Inclusion in semipermeable membrane structures.

Pharmaceutical Industry

Vaccine Production

Classical methods of vaccine production include:

• Attenuating the virulence of the organism, usually with formaldehyde.
• Killing microorganisms, usually by heat.
• Inactivating toxins while retaining immunogenicity (toxoids).

Serum Production

Obtained from animals inoculated with an organism, from which antibodies are extracted.

Antibiotic Production

The process is summarized as follows:

1. Cultivation: Growing the producer fungus in optimal conditions (e.g., Penicillium chrysogenum for penicillin).
2. Purification: Usually via physical processes such as centrifugation or filtration.
3. Crystallization: Final compound recovery.

The process is optimized by selecting more productive strains via conventional genetic procedures (mutation, recombination) and controlling growth parameters.