History of Immunization, Antiseptics, and Antibiotics

Microbiology Basics

• A microbe is a microorganism, a microscopic living organism.
• Microbes include bacteria, archaea, viruses, and prions.

Contributions to Microbiology

• Fred Sanger developed a method for determining the order of nucleotide bases in DNA, which enabled the study of microbial genetics.
• Antonie van Leeuwenhoek is considered the "Father of Microbiology" for his discovery of microorganisms using single-lens magnifiers.
• John Graunt is credited with founding the science of medical statistics.

Types of Microbes

• Bacteria and archaea are prokaryotes, lacking a true nucleus.
• Viruses and prions are not cellular and do not have a nucleus.
• Eukaryotes, including plants and animals, have a true nucleus.

Microbial Diversity and Evolution

• Microbial diversity is related to the age of Earth, with ancient microbes providing a window into the planet's history.
• Metagenomes, the genetic material of entire microbial communities, are important for studying microbes.
• The discovery of archaea by Carl Woese challenged existing biological classifications and revealed a new domain of life.

Microbial Evolution and Classification

• Carl Woese's analysis of prokaryotes living in hot springs challenged existing biological classifications and led to the discovery of archaea.
• Lynn Margulis proposed the mechanism of endosymbiosis, where ancient bacteria were engulfed by eukaryotic cells, leading to the evolution of organelles like mitochondria and chloroplasts.
• DNA analysis played a key role in Carl Woese's discovery of archaea as a distinct form of life.

Challenges in Microbiology

• The statement "Microbial species are hard to define" poses a challenge for microbiologists when classifying organisms, as it is difficult to define a species in the microbial world.

Historical Context

• Mycobacterium tuberculosis caused tuberculosis, a major disease in the 19th century.
• Yersinia pestis caused the plague, a pandemic in the 14th century.
• The theory of spontaneous generation suggested that living creatures could arise without parents, which was later disproven.

Key Discoveries

• Alexander Fleming discovered the substance that kills bacteria, leading to the commercial antibiotic Penicillin.
• The discovery of Penicillin was significant because it revolutionized the treatment of bacterial infections.
• Sergei Winogradsky studied bacteria that can fix nitrogen, which led to a better understanding of microbial metabolism.

Endosymbiosis

• Endosymbionts are organisms that live within other cells, providing a key role in the evolution of eukaryotic cells.

Classification Systems

• Carl Woese's classification system differed from the previous scheme of five kingdoms in that it recognized archaea as a distinct domain of life.
• The major contribution of Lynn Margulis to the understanding of eukaryotic evolution was the proposal of endosymbiosis.