History of Microbiology

• Microbiology explores microorganisms, a diverse group existing as single cells or clusters.
• Microbiology includes bacteria, archaea, algae, fungi, protozoa, and non-cellular viruses.
• Microbiology emerged in the mid-1800s when Louis Pasteur showed that microorganisms cause fluid fermentation.

History of Microbiology

• Early civilizations documented epidemic, transmissible diseases.
• Agriculture influenced disease via epizootic transmission.
• Egyptian, Greek, and Roman civilizations experienced documented plagues.
• Renaissance explorations spread pathogens, creating new contexts for disease understanding.
• Abiogenesis was considered as a disease explanation.
• Understanding in the field increased through optics and causality.
• John Snow published a pamphlet in 1849 speculating that cholera was waterborne or foodborne.
• Snow challenged the miasma theory, which attributed diseases to bad air.
• An 1854 London cholera outbreak supported Snow's waterborne illness hypothesis.
• Snow mapped cholera cases, noting proximity to water-drawing sites.
• The highest incidence was near a pumping station drawing water downstream from sewer effluent.
• John Snow is credited as the father of epidemiology for this work.
• Louis Pasteur, in 1857, demonstrated microorganisms' role in fluid fermentation.
• Pasteur disproved spontaneous generation, attributing contamination to environmental microorganisms.
• Pasteur proved that sterilization could maintain sterile conditions, launching modern microbiology.
• Robert Koch studied under Jakob Henle and learned the importance of experimentation in understanding disease.
• Koch identified Bacillus anthracis in infected sheep and transmitted it to healthy animals.
• Koch pioneered single colony isolation on solid media which he called Petri dishes.
• Koch isolated Mycobacterium tuberculosis from infected patients.

Koch's postulates:

• Microbes must be found in all cases of the disease.
• The pathogen must be isolated and cultured.
• The pathogen should cause disease in animal models.
• The same pathogen must be re-isolated from the infected animal.

Koch vs. Pasteur

• Koch focused on pathogens causing specific diseases, viewing microbes as immutable species needing elimination, using solid medium for single colony isolation.
• Pasteur, with a chemistry background, saw microbes as mutable, instructed entities in fermentation, and used broth cultures to study microbial communities.

Optics and Microscopy

• Microscopes are essential since individual microbes lack visibility without aid.
• Improved imaging technology advances understanding of microbes and diseases.
• Microscopes vary in resolving power, which defines the distance needed to distinguish two light sources as separate images.
• Microscope types include light microscopes, electron microscopes, confocal scanning, and scanning probes.

Light Microscopy facts

• Light microscope resolving power is about half the wavelength of light used.
• With 0.4 mm yellow light, the smallest separable diameters are about 0.2 mm.
• Useful microscope magnification makes the smallest resolvable particles visible
• Common light microscopes include bright field, phase contrast, dark field, and fluorescence microscopes.

Electron Microscopy facts

• Electron microscopes allow for the detailed observation of cell structures.
• Shorter electron wavelengths provide better resolution than white light photons
• Two main types are transmission (TEM) and scanning (SEM) electron microscopes.
• TEM projects an electron beam onto a thin specimen.
• Varying electron scattering reveals specimen details.
• Electrons that strike the specimen get gathered and focused for enlargement
• TEM resolves particles 0.001 mm apart.
• SEM has lower resolution but produces 3D images of microscopic object surfaces

Microbial Biology

• Eukaryotes have membrane-bound nuclei, unlike prokaryotes.
• Eukaryotes and prokaryotes have distinct differences.
• Eukaryotes are distinguished by size and specialized organelles like, mitochondria.
• Eukaryotic microorganisms, or Eukarya, are unified by cell structure and phylogenetic history.
• Eukaryotic microorganisms include algae, protozoa, fungi, and slime molds.

Future Advances

• Future advances are expected when the genomics and the promise of personalised medicine is fully realised.
• Further directed inquiry into the fundamental nature of microbes and immune defenses is needed.
• More work remains before the benefits of these discoveries applied equally worldwide.
• Microbiology greatly impacts the health and welfare of humankind.
• Mortality from infectious diseases has decreased substantially over the last 100 years due to public health, vaccines, and anti-infective chemotherapy.
• Class administration will follow familiar track.
• Microbiology is the study of small and biologically relevant entities.
• Disease study and development of germ theory shaped the field.
• Optical technologies limited initial microbe descriptions.
• Microbe nomenclature often reflects optical observations.

A brief look into the history of microbiology, including the contributions of Louis Pasteur, the understanding of disease in early civilizations, and John Snow's work on cholera. This exploration covers the evolution of our understanding in the field.