Microbiology and Microorganisms Overview

Microbiology and Microorganisms

• Microbiology studies microscopic organisms, including bacteria, fungi, protozoa, algae, and viruses.
• Microorganisms are too small to be seen without a microscope and can be pathogenic or beneficial.
• Functions of microbes include decomposition of organic waste, oxygen generation through photosynthesis, production of chemicals (e.g., ethanol, acetone), and fermentation of foods (e.g., cheese, vinegar, bread).
• Understanding microorganisms helps prevent food spoilage, disease, and control outbreaks.

Human Microbiome

• The human body contains approximately 30 trillion cells and harbors around 40 trillion bacterial cells.
• The microbiome consists of microbes helping maintain health, preventing pathogenic growth, and supporting the immune system.

Classification and Nomenclature

• Scientific naming system established by Carolus Linnaeus in 1735, involving genus and specific epithet (species).
• Scientific names are italicized or underlined, with the genus capitalized and specific epithet in lowercase.
• Example: Escherichia coli honors Theodor Escherich and describes its habitat in the large intestine.
• Staphylococcus aureus refers to its clustered spherical shape and gold-colored colonies.
• After first use, names can be abbreviated (e.g., E. coli, S. aureus).

Types of Microorganisms

• Major categories include bacteria, archaea, fungi, protozoa, algae, viruses, and multicellular animal parasites.

Characteristics of Microorganisms

• Bacteria: Prokaryotic, single-celled, with peptidoglycan cell walls, reproduce by binary fission, and may move using flagella.
• Archaea: Prokaryotic, lack peptidoglycan, thrive in extreme environments (methanogens, extreme halophiles, and thermophiles).
• Fungi: Eukaryotic, have chitin cell walls, absorb organic chemicals for energy; include unicellular yeasts and multicellular molds/mushrooms.
• Protozoa: Eukaryotic, absorb or ingest organic materials, motile via pseudopods, flagella or cilia; can be free-living or parasitic.
• Viruses: Acellular, consist of a DNA or RNA core surrounded by a protein coat, replicate only inside a host cell.

Historical Insights in Microbiology

• First observations of microbes by Anton van Leeuwenhoek (1623–1673).
• Robert Hooke (1665) discovered cells, contributing to cell theory.

Spontaneous Generation vs. Biogenesis

• Spontaneous generation suggests life arises from nonliving matter, while biogenesis states life arises from preexisting living cells.
• Louis Pasteur disproved spontaneous generation, demonstrating the presence of microorganisms in the air.

Contributions of Louis Pasteur

• Pasteur identified that microbes caused fermentation and spoilage in food/beverages.
• Developed pasteurization, a process using heat to kill harmful bacteria without destroying beverages.

Germ Theory of Disease

• In 1876, Robert Koch's research established that specific bacteria cause specific diseases, leading to Koch's postulates.

Vaccination

• In 1796, Edward Jenner used cowpox virus to confer immunity against smallpox, laying groundwork for vaccination.

Modern Chemotherapy

• Chemotherapy refers to disease treatment using chemicals, including synthetic drugs and antibiotics, which originate from bacteria and fungi.
• Paul Ehrlich introduced the "magic bullet" concept for targeting pathogens without harming hosts, leading to treatments like Salvarsan for syphilis.

Discovery of Antibiotics

• In 1928, Alexander Fleming discovered penicillin from the Penicillium fungus, later mass-produced in the 1940s to combat bacterial infections.