Microbes in Industrial Products

• Microbes are used to synthesise many products valuable to human beings, including beverages, organic acids, vitamins, growth hormones, enzymes, antibiotics, and other useful compounds.
• These products are secondary metabolites produced during the idiophase and are not required for microbial growth.
• The substrate type and the microorganism type determine the secondary metabolite produced.

Mechanism: Microbes produce secondary metabolites during the stationary (idio) phase in large vessels called 'fermenters' (e.g., tubular tower fermenters).

Tubular tower fermenter

Fermentors

Fermentation Plant

Alcoholic Beverages: Saccharomyces cerevisiae var. ellipsoideus (Brewer’s yeast) ferments malted cereals and fruit juices into ethanol.

• Without Distillation: Wine and Beer.
• With Distillation: Whisky, brandy, and rum.

Traditional Drinks: Palm sap fermentation is used in South India. 'Fenny' is a traditional wine in Goa made by fermenting cashew fruit pedicels.

Zymology is the applied science that deals with the biochemical processes of fermentation and their practical uses.

Oenology is the science and study of wine and winemaking.

Microbes convert glucose or end products (like pyruvate/ethanol) into organic acids used in food and industry:

• Citric Acid & Gluconic Acid: Aspergillus niger (Fungus)
• Fumaric Acid: Rhizopus arrhizus
• Acetic Acid: Acetobacter aceti (Bacterium)
• Butyric Acid: Clostridium butylicum (Bacterium)
• Lactic Acid: Lactobacillus (Bacterium)
• Itaconic Acid: Aspergillus itaconicus

Enzymes act as biocatalysts and are excreted into the surrounding medium by microbes during industrial culturing:

• Pectinases & Proteases: (Sclerotinia libertine, Aspergillus niger) Used in the food industry to clarify bottled fruit juices.
• Lipases: (Candida lipolytica) Used in detergent formulations to remove oily stains from laundry.
• Invertase: (Saccharomyces cerevisiae)
• Cellulase: (Trichoderma koningii)

• Streptokinase: Produced by Streptococcus bacteria. Genetically modified and used as a "clot-buster" for heart attack patients.
• Cyclosporin A: Produced by the fungus Trichoderma polysporum. Used as an immunosuppressive agent for organ transplant patients.
• Statins: Produced by the yeast Monascus purpureus. Acts as a competitive inhibitor to lower blood cholesterol.
• Human Proteins & Vaccines: Recombinant DNA technology uses E. coli to produce human insulin (humulin). Attenuated pathogens are used to produce vaccines.
• Ergot: Prepared from the fungus Claviceps purpurea; used to induce uterine contractions and check haemorrhages.

Antibiotics ("against life" of pathogens) are secondary metabolites used to treat deadly diseases. Penicillin (from Penicillium notatum) was the first discovered by Alexander Fleming, with its potential established by Chain and Florey.

Vitamins: Microbes synthesise vitamins required for human diets.

• Vitamin B₂: Neurospora gossypii / Eremothecium ashbyii
• Vitamin B₁₂: Pseudomonas denitrificans / Propionibacterium shermanii
• Vitamin C: Aspergillus niger

Amino Acids: Lysine is produced via microbial fermentation using Corynebacterium glutamicum as an animal feed supplement.

Gibberellins: Plant growth hormones isolated from the fungus Gibberella fujikuroi. Used practically to induce parthenocarpy and increase fruit size (e.g., grapes).

• Microbes are cultured in large industrial fermenters to produce highly valuable secondary metabolites during their stationary growth phase.
• Specific strains of yeast are widely utilised in the commercial fermentation process to manufacture various alcoholic beverages from cereals and fruit juices.
• Industrial enzymes secreted by microbes serve practical daily purposes, such as clarifying bottled fruit juices and removing stubborn stains in laundry.
• Microorganisms are the primary source of life-saving medical treatments, producing essential antibiotics and critical bioactive molecules like immunosuppressants.
• Advanced biological techniques rely on microbes to commercially synthesise essential human proteins, dietary vitamins, and plant growth hormones.