Biology of Microbial Cells Lecture 1

Introduction to Microbiology

• Microbiology is the study of very small living organisms, including bacteria, algae, protozoa, fungi, and viruses.
• Microorganisms are required to be studied using a microscope.

Microorganisms

• Microorganisms (MOs) include bacteria, algae, protozoa, fungi, and viruses.
• Viruses are infectious agents or particles.
• Only 3% of known microorganisms are pathogens, while 97% are non-pathogens, and 87% are beneficial.
• Indigenous microflora or microbiota refers to microorganisms that are naturally present in a specific environment.
• Microorganisms are ubiquitous, meaning they are present everywhere.

Historical Background

• The concept of microorganisms was initially suggested by the spread of diseases, which implied the existence of invisible, transmissible agents of infection.
• Antony Van Leeuwenhoek referred to microorganisms as "animalcules".
• The theory of spontaneous generation suggested that living organisms arise from decomposing organic matter, but this was later disproven.

The Golden Age of Microbiology

• Louis Pasteur showed that microbes cause fermentation and spoilage, disproved spontaneous generation, and developed aseptic techniques.
• Pasteur's work laid the foundation for modern microbiology.

Experiment of Pasteur

• Pasteur's experiment demonstrated the role of microorganisms in fermentation and spoilage.

Microbiology and Medicine

• The germ theory of disease states that diseases are transmitted by microorganisms from a diseased to a healthy person.
• Examples of diseases caused by microorganisms include diphtheria (caused by Corynebacterium diphtheriae) and tetanus (caused by Clostridium tetani).

Robert Koch

• Robert Koch developed solid growth media, pure culture techniques, simple stain techniques, and aseptic lab techniques.
• Koch isolated bacteria as causative agents for anthrax.

Koch's Postulates

• Koch's Postulates are a series of experimental steps to show that a specific organism causes a specific disease.

Spores and Sterilization

• Ferdinand Cohn discovered and described endospores.
• The term "sterile" means the complete removal of all life forms, including endospores.

Branches of Microbiology

• Basic Microbiology: classifications, metabolism, metabolic pathways, nutrition, growth, and its requirements.
• Medical Microbiology: human pathogens.
• Industrial Microbiology: microorganisms used to obtain industrial products.
• Pharmaceutical Microbiology: production of drugs, enzymes, solvents, alcohols, etc. by microorganisms.
• Agricultural Microbiology: microorganisms used as biofertilizers and biocontrol agents of plant pathogens.
• Environmental Microbiology (Microbial Ecology): pollution of soil, air, and water, and biodegradation of toxic chemicals by various microorganisms.