Microbes in Human Welfare

Introduction to Microbes in Human Welfare

Microorganisms, commonly called microbes, are microscopic living organisms that are found everywhere on Earth. They inhabit diverse environments such as soil, water, air, and even inside the bodies of humans, animals, and plants. Some microbes thrive in extreme conditions like thermal vents with temperatures as high as 100°C, deep underground soil layers, beneath thick snow, and in highly acidic environments. The diversity of microbes includes bacteria, fungi, protozoa, viruses, viroids, and prions. While many microbes are microscopic, some bacteria and fungi can grow on nutritive media to form visible colonies. These colonies are useful for studying microbial characteristics and functions. Despite their association with diseases, microbes play a crucial role in human welfare by contributing to food production, industrial processes, medicine, environmental management, and agriculture. This chapter explores the various beneficial roles of microbes in human welfare.

• Microbes are present in all environments including extreme habitats.
• Types of microbes include bacteria, fungi, protozoa, viruses, viroids, and prions.
• Some bacteria and fungi form visible colonies on nutritive media.
• Microbes have both harmful and beneficial roles.
• This chapter focuses on the beneficial uses of microbes in human welfare.
• 📌 Microbes: Microscopic organisms including bacteria, fungi, viruses, etc.
• 📌 Colonies: Visible clusters of microbes grown on nutritive media.
• 📌 Prions: Proteinaceous infectious agents without nucleic acids.

8.1 Microbes in Household Products

Microbes are extensively used in the preparation of various household products, particularly fermented foods and beverages. One common example is the production of curd from milk. Lactic acid bacteria (LAB), such as Lactobacillus species, grow in milk and convert it into curd by fermenting lactose into lactic acid. This acid coagulates and partially digests milk proteins, improving the texture and nutritional quality of curd, including an increase in vitamin B12 content. A small amount of curd acts as an inoculum containing millions of LAB, which multiply at suitable temperatures to convert fresh milk into curd. LAB also play a beneficial role in the human stomach by inhibiting disease-causing microbes. Fermentation is also involved in making dough for foods like dosa and idli. The puffed-up appearance of the dough is due to carbon dioxide (CO2) gas produced by bacterial metabolism, specifically through fermentation pathways such as alcoholic fermentation or heterolactic fermentation. The bacteria responsible for these fermentations often come from the environment or starter cultures. Similarly, baker’s yeast (Saccharomyces cerevisiae) ferments dough for bread, producing CO2 that causes the dough to rise. Traditional fermented drinks like toddy are made by fermenting palm sap using microbes. Fermentation is also used for making fermented fish, soyabean, and bamboo shoots. Cheese, one of the oldest fermented foods, owes its characteristic texture, flavor, and taste to specific microbes. For example, Propionibacterium sharmanii produces CO2 that forms large holes in Swiss cheese, while fungi ripen Roquefort cheese, imparting a distinct flavor.

• Lactic acid bacteria convert milk into curd by fermenting lactose to lactic acid.
• Fermentation produces CO2 causing dough to rise in foods like dosa, idli, and bread.
• Baker’s yeast (Saccharomyces cerevisiae) is used in bread making.
• Traditional fermented drinks and foods involve microbial fermentation.
• Specific microbes impart unique flavors and textures to different cheeses.
• 📌 Lactic Acid Bacteria (LAB): Bacteria that ferment lactose to lactic acid.
• 📌 Fermentation: Metabolic process converting sugars to acids, gases, or alcohol.
• 📌 Inoculum: Starter culture containing microbes to initiate fermentation.