Microbe

Microbe

A microbe or microorganism is a microscopic organism, which may exist in its single-celled form or in a colony of cells.

The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from 6th century BC India and the 1st century BC book On Agriculture by Marcus Terentius Varro. Microbiology, the scientific study of microorganisms, began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera and anthrax.

Microorganisms are very diverse; they include bacteria, fungi, archaea, and protists. They also include viruses and prions, though these are not usually classified as living organisms. Microbes live in all parts of the biosphere where there is liquid water, including soil, hot springs, on the ocean floor, high in the atmosphere and deep inside rocks within the Earth's crust.

Microbes are critical to nutrient recycling in ecosystems as they act as decomposers. Some microbes are pathogenic, causing disease and even death in plants and animals. As inhabitants of the largest organ of the human body, the skin, and the human gut, microbes play a critical role in human health and disease. A small number of species cause disease, but most are harmless or beneficial.

History

The possible existence of microorganisms was discussed for many centuries before their discovery in the 17th century. The existence of unseen microbial life was postulated by Jainism which is based on Mahavira’s teachings as early as 6th century BCE. In his first century BC book On Agriculture, Roman scholar Marcus Terentius Varro was the first to warn about diseases that could be caused by microorganisms.

Microbiology

Microbiology is the scientific study of microorganisms, including a wide variety of organisms ranging from bacteria to parasites. This discipline includes fundamental research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents.

Types of Microbes

Microorganisms are very diverse and include all the bacteria and archaea and almost all the protozoa. They also include some fungi, algae, and certain animals, such as rotifers. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses (and viroids) as microorganisms, but others consider these as nonliving.

Role in Ecosystem

Microbes are critical to nutrient recycling in ecosystems as they act as decomposers. A small amount of microbes are pathogenic, causing disease and even death in plants and animals.

Role in Human Health

As inhabitants of the largest organ of the human body, the skin, and the human gut, microbes play a critical role in human health and disease. A small number of species cause disease, but most are harmless or beneficial.

See Also

• Bacteria
• Fungi
• Archaea
• Protists
• Viruses
• Prions
• Microbiology
• Pathogen

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