Relationship Between Microorganisms and Humans
8 Minutes
Microorganisms for kids: learn how harmful, harmless, and useful microbes interact with human life. A science lesson in English.
- What microbes are and how we use a microscope to see them
- Harmful Salmonella bacteria and how the immune system attacks them
- Rain smell from actinomycetes and useful Lactobacillus in curd
What this lesson teaches
Microorganisms, or microbes (nunreergal in Tamil), are tiny living forms that are more than one hundred times smaller than a mustard seed and cannot be seen with the naked eye. They live all around us and inside our bodies, dividing into three main groups: harmful, harmless, and useful microbes. Scientists view them using a microscope, which acts like a specialized magnifying glass.
Harmful microbes and body defense
Harmful microbes include certain bacteria, viruses, and fungi that cause diseases such as fevers and colds. For instance, the influenza virus causes colds, while the bacterium Salmonella typhi causes typhoid. In a laboratory, scientists can grow Salmonella on pink media plates, where a single visible cluster can contain nearly a billion bacteria. When dangerous microbes enter the body, the immune system acts like a defense force, attacking the intruders and saving information about them so it can fight them off more effectively if they ever return. Vaccines given during childhood also help prepare this internal defense system.
Harmless microbes in the environment
Harmless microbes live in the environment without causing harm or offering direct health benefits to humans. They simply exist in nature while carrying out their own natural life cycles. A common example is actinomycetes, a type of microbe found in the soil. When rain falls on dry earth, these microbes are responsible for producing the distinct, pleasant earthy smell that spreads through the air.
Useful microbes and human digestion
- Useful microbes are essential for food preparation, helping turn milk into curd, fermenting idli and dosa batter, and improving the taste of baked foods like cake.
- A beneficial bacterium called Lactobacillus lives inside the human digestive tract, where it helps break down food particles so the body can absorb them.
- When food stays undigested in the stomach and reduces nighttime hunger, it often indicates that the count of beneficial gut microbes is too low.
- Consuming curd delivers fresh microbes directly to the stomach, restoring microbial balance and making digestion easier.
- Foods that have these living, beneficial microbes added to them are called probiotics.