Use of microorganisms in industry and agriculture — A/L Biology

What must I remember about Use of microorganisms in industry and agriculture?

• Microorganisms are exploited across diverse industrial, agricultural, and environmental biotechnology applications due to their immense metabolic diversity, rapid growth kinetics, and genetic manipulability.
• Industrial Fermentations: Primary metabolites produced during exponential trophophase (e.g., Ethanol produced by Saccharomyces cerevisiae via alcoholic fermentation of sugars; Acetic acid produced by Acetobacter aceti; Lactic acid by Lactobacillus); Secondary metabolites produced during stationary idiophase (e.g., Penicillin antibiotic produced by Penicillium chrysogenum).
• Enzyme Technology & Bio-products: Microbial enzymes synthesized at industrial scale using bioreactors: Proteases (detergents, meat tenderization from Bacillus subtilis), Amylases (starch hydrolysis to glucose from Aspergillus oryzae), Pectinases (fruit juice clarification), and single-cell protein (SCP: Spirulina, Methylophilus).
• Agricultural Applications: Biological Nitrogen Fixation (Rhizobium symbioses with legumes, free-living Azotobacter, Azospirillum), Biofertilizers (Mycorrhizal fungi mobilizing soil phosphate), and Biopesticides (Bacillus thuringiensis producing Cry endotoxins lethal to insect pest larvae).
• Environmental Bioremediation: Exploitation of microbes to degrade toxic environmental contaminants into harmless end-products: Pseudomonas putida genetically engineered to metabolize petroleum hydrocarbons in oil spills; anaerobic methanogens in biogas digesters converting organic wastes into renewable methane (CH4) fuel.

Test yourself (1 minute)

1. Primary vs Secondary Metabolite kinetics

   Primary metabolites (ethanol, amino acids) are synthesized during the log / exponential growth phase (trophophase) as essential metabolic byproducts; Secondary metabolites (antibiotics, toxins) are non-essential for vegetative growth and accumulate during the stationary phase (idiophase).

2. Bioreactor batch vs continuous culture

   Batch fermentation operates as a closed system with a fixed nutrient charge; Continuous culture (chemostat) pumps fresh sterile nutrients continuously while withdrawing effluent to keep microbes permanently in exponential growth phase.

3. Bacillus thuringiensis (Bt) Cry toxin specificity

   Inactive protoxins solubilize only in alkaline insect midgut (pH > 9.0), cleaved by proteases into active Cry delta-endotoxin pores that lyse gut epithelial cells, proving harmless to humans and non-target vertebrates with acidic stomachs.

Practise Use of microorganisms in industry and agriculture questions today

Source: NIE G.C.E. (A/L) Biology Syllabus & Resource Book, Unit 9

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Where does Use of microorganisms in industry and agriculture fit in the syllabus?

Year 2 · Term 3