Notes on Microbes in Human Welfare
Microorganisms (microbes) form a diverse group of life forms that play crucial roles in sustaining not just ecosystems but also human welfare by enhancing food production, health, and the environment. This chapter delves into various applications of microbes across different domains.
8.1 Microbes in Household Products
- Lactic Acid Bacteria (LAB): Microbes like Lactobacillus convert milk into curd, enriching nutritional value by enhancing vitamin B content. LAB also aid in digestion in the human gut.
- Fermentation in Foods: Fermentation is pivotal in creating dough for dosa, idli, and bread. Specific yeast, Saccharomyces cerevisiae, ferments sugars, producing carbon dioxide (CO₂) that leavens the dough. Fermented foods include traditional items like toddy and various fermented soy products.
- Cheese Production: Cheese varieties derive their distinct tastes and textures from specific microbial cultures; for example, Propionibacterium sharmanii contributes to the holes in Swiss cheese and mold on Roquefort cheese gives it a unique flavor.
8.2 Microbes in Industrial Products
- Production of Alcohol: Yeasts, particularly Saccharomyces cerevisiae, are integral in brewing beer, wine, and spirits through fermentation, transforming malted cereals and fruit juices into ethanol.
- Antibiotics: Penicillin was the first antibiotic discovered, and its potential was realized through the work of Fleming, Chain, and Florey. Antibiotics are crucial in treating bacterial infections and diseases affecting humans.
- Other Products: Microbes produce a plethora of chemicals such as citric acid from Aspergillus niger and enzymes used in cleaning products and food processing. Streptokinase, a clot-dissolving enzyme, is vital in medical treatments.
8.3 Microbes in Sewage Treatment
- Sewage Composition: Municipal sewage, rich in organic matter and harmful microbes, requires treatment before disposal to prevent pollution.
- Primary Treatment: This includes physical processes to remove larger solid particles through filtration and sedimentation, separating solid waste (primary sludge) from liquid effluent.
- Secondary Treatment: Involves biological treatment where aerobic microbes actively break down organic matter, reducing BOD (Biochemical Oxygen Demand), which measures the amount of oxygen consumed by microbes in water. The remaining sludge is either recycled or digested to produce biogas.
8.4 Microbes in Production of Biogas
- Biogas Formation: Anaerobic bacteria in sludge digest waste, producing biogas (mostly methane), providing an alternative energy source for cooking and heating in rural areas. Cattle dung is a prime input for biogas production.
- Biogas Plant: Consists of a tank for collecting waste and facilitating the microbial process to produce gas; the remaining slurry can serve as fertilizer.
8.5 Microbes as Biocontrol Agents
- Biological Pest Control: Employs natural predators and parasites instead of toxic chemicals to manage pest populations. The target is to control harmful pests without affecting beneficial organisms. Bacillus thuringiensis, a bacteria, effectively targets specific insect larvae.
- Genetic Engineering: Innovations have allowed genes from beneficial microbes to be introduced into crops (like Bt cotton), enhancing pest resistance naturally and reducing pesticide use.
- Other Bioagents: Trichoderma fungi and baculoviruses are examples of potential biocontrol organisms used to combat plant pathogens and insect pests, respectively.
8.6 Microbes as Biofertilisers
- Nutrient Enrichment: Biofertilisers, composed of beneficial bacteria and fungi, enrich soil fertility. Rhizobium forms nodules on legume roots, helping in nitrogen fixation.
- Mycorrhizae: Fungi associations with plant roots increase phosphorus uptake and improve resilience against disease and environmental stresses.
- Cyanobacteria: These microbes fix atmospheric nitrogen and enhance soil fertility in paddy fields, contributing organic matter to the soil.
Summary
The chapter highlights that while many microbes can cause diseases, countless others serve beneficial roles that are vital for human welfare through food production, disease treatment, environmental management, and sustainable agriculture. Understanding and utilizing microbial processes can enhance quality of life and safeguard the environment.