Introduction to Microbiology

• Microbiology is the study of microbes, including nonliving entities and living organisms
• Microbes are ubiquitous and can be found everywhere

Microbes Categories

• Viruses
• Bacteria
• Archaea
• Protozoa
• Algae
• Fungi
• Germs are the microbes that cause disease

Pathogens

• Disease-causing microorganisms known as pathogens or infectious agents
• Only about 3% of known microbes cause disease

Why Study Microbiology?

• Microbes live on and in bodies
• These microbes are known as indigenous microbiota, human microbiome, or human bioneme
• Microbes are essential for life on Earth
• Many microbes are involved in decomposing dead organisms and waste, referred to as decomposers or saprophytes
• Some microbes decompose industrial wastes and this is called bioremediation
• Microbes are involved in cycles such as carbon, nitrogen, oxygen, sulfur, and phosphorous cycles
• The relationships between microbes and the environment is microbial ecology
• Algae and bacteria are food for tiny animals
• Microscopic ocean organisms, known as plankton, start many food chains
• Tiny marine plants and algae are phytoplankton and tiny marine animals are zooplankton
• Some microbes live in animal intestines, aiding digestion and producing valuable substances.
• Microbes are essential in various food and beverage industries, producing enzymes and chemicals

Microbe roles

• Certain bacteria and fungi produce antibiotics to treat infectious diseases
• An antibiotic is a substance produced by a microbe effective in killing or inhibiting growth of other microbes
• The antibiotic industry is an example of biotechnology
• Microbes are essential in genetic engineering
• Microbiologists engineer bacteria and yeast to produce useful substances like insulin, growth hormones, interferons, and vaccines
• Microbes are used as "cell models"
• E. Coli studies have helped define cell, composition and inner workings, including those of human cells
• Microbes can cause infectious diseases and microbial intoxications

Microorganism History

• Fossils of primitive microbes (11 types) founded in north-western Australia date 3.5 billion years ago
• Candidates for being the first microbes on earth are archaea and cyanobacteria
• Infectious diseases of animals/humans have been around for as long as the species have existed
• Bacterial diseases, like tuberculosis, leprosy, and syphilis, malaria, or parasitic worm infections, have been present around for a long time
• The earliest known account of a "pestilence" occurred in Egypt about 3180 bc
• In 1900 bc, near the end of the trojan war one may find the an epidemic of what is thought to have been bubonic plague which decimated the Greek army
• About 1500 bc, the Ebers papyrus, describing epidemic fevers, was discovered in a tomb in Thebes - Egypt
• China had the a disease may have been smallpox around 1122 bc
• Epidemics of plague had a presence in Rome and Greece around 790/710/640/430 bc respectively
• In early accounts, there may have been rabies, anthrax, dysentery, smallpox, ergotism, botulism, measles, typhoid and typhus fever, diphtheria, and syphilis
• The French called syphilis the Neapolitan disease; the Italians called it the French or Spanish disease
• The English called syphilis the French pox. Various names for syphilis was Spanish, German, Polish, and Turkish pocks. The name "syphilis" was introduced to the disease around 1530

Pioneers of Microbiology

• Anton van Leeuwenhoek (1632-1723) was the first person to see live bacteria and protozoa
• He is sometimes referred to as the Father of Microbiology, Bacteriology and Father of Protozoology
• Van Leeuwenhoek was not a trained scientist
• His hobby was grinding tiny glass lenses, mounting in small metal frames and as a result created single-lens microscopes or simple microscopes to observe "animalcules"
• Letters by Leeuwenhoek convinced scientists of the late 17th century of the existence of microbes
• Many scientists observing at the time believed life could develop from inanimate substances
• Scientists believed life can arise spontaneously from nonliving material, which is called the theory of spontaneous generation or abiogenesis
• There was a man named Rudolf Virchow in 1858 whom proposed the theory of biogenesis and Louis Pasteur (along with John Tyndall) discovered that disproved spontaneous generation, and proved life can only arise form preexisting life
• Louis Pasteur (1822-1895) was a French chemist who made contributions to the newly emerging field of Microbiology which many consider to be the foundation of the science of microbiology and cornerstone of modern medicine

Pasteur's Contributions

• In attempts find out why wine contaminated, Pasteur discovered alcoholic fermentation
• Pasteur found different types of microbes produce different fermentation produce
• As an example, yeasts convert glucose found in grapes into ethyl alcohol (ethanol) by fermentation, and contaminating bacteria, such as Acetobacter, convert glucose to acetic acid (vinegar), ruining the wine
• Through his experiments, Pasteur killed the theory of spontaneous generation
• Pasteur discovered life could exist in the absence of oxygen
• Introduced the terms “aerobes" (organisms requiring oxygen) and "anaerobes" (organisms not requiring oxygen)
• Pasteur designed a process (today known as pasteurization) to kill microbes that were causing wine to spoil
• An economic concern to France's wine industry, Pasteurization kills pathogens in many types of liquids
• Pasteur's process involves heating wine to 55°C for several minutes and these days it is accomplished heating liquids to 63°C to 65°C for 30 minutes or to 73°C to 75°C for 15 seconds. It should be noted that pasteurization does not kill all the microbes in liquids just the pathogens.
• He also discovered the infectious agents harming the silk industry and how to prevent those diseases
• Made additions to the germ theory of disease, the theory that specific microbes cause specific infections
• He championed hospital change to minimize contamination from pathogens
• He developed vaccines to prevent chicken cholera, anthrax, and swine erysipelas (a skin disease).
• Pasteur developed a vaccine to prevent rabies in dogs and used it to treat rabies for humans
• Pasteur Institute founded in 1888, a clinic for rabies treatment, research center for infectious diseases, and a teaching center.
• The first foreign institute was founded in Saigon, Vietnam, known as Ho Chi Minh City
• Alexandre Emile Jean Yersin, a former student of Robert Koch and Louis Pasteur-who, in 1894, discovered the bacterium that causes plague

Robert Kock

• Robert Koch (1843–1910), a German physician, made contributions to microbiology.
• He made additions to the germ theory of disease.
• Koch discovered that B. anthracis has spores that can resist adverse conditions
• He developed methods to fix, stain and photograph bacteria
• Also, developed methods for cultivating bacteria on solid media
• Koch discovered the bacterium (M. tuberculosis) that causes tuberculosis, and the bacterium (Vibrio cholerae) for cholera
• Koch's work on tuberculin (a protein derived from M. tuberculosis) ultimately was used for testing the skin for tuberculosis diagnosis

Exceptions to Kochs Postulates

• A microbe must be able to be found in all cases of the disease AND not be present in healthy animals
• The microbe must be isolated from the diseased animal or human and grown in pure culture in the lab.
• Microbes from the pure culture must produce it when inoculated into healthy susceptible animals.
• Microbe must once again be recovered from the experimentally infected animals and grown in pure culture

Exceptions to Koch's Postulates

• You need to be able to grow the pathogen in the lab
• Some pathogens grow on artificial media
• To fulfill there needs to be an infection of laboratory animals with the pathogen
• A lot of pathogens are species specific, which only infects one species
• Some diseases are due to synergistic or polymicrobial infections, which is more than one microbe causing the infection
• Another difficult is growing the altered pathogens which some when grown in vitro

Careers in Microbiology

• A microbiologist is the scientist studying microbes. They may have a bachelor's, master's, or doctoral degree in microbiology.
• A bacteriologist specializes in bacteriology, functions, and activities of bacteria.
• Scientists studying phycology (or algology) study algae
• Protozoologists explore protozoa
• Those specialising in fungi are mycologists
• Virology encompasses the study of viruses and their effects on living cells of all types.
• Virologists/cell biologists may transfer genetic material (DNA).
• Other fields apply how a knowledge of microbiology may applied to aspects of society, medicine, and industry

Medical Microbiology

• Excellent career field, for those interested in medicine and microbiology.
• Medical microbiology: the study of pathogens, the diseases, the body's defenses against disease.
• The field of medical microbiology may concern, epidemiology, transmission of pathogens, disease, immunology, and the production of vaccines protect diseases

Clinical Microbiology

• Branch of medical microbiology concerned with the laboratory diagnosis of infectious diseases.
• Very excellent career field for those interested in laboratory sciences and microbiology.