BIOL 3340 BIOL 3340

Chapter 1 Chapter 1

The HistoryThe History

andand

Scope of MicrobiologyScope of Microbiology

The Importance of The Importance of MicroorganismsMicroorganisms

medical and most populous group of medical and most populous group of organisms and are found everywhere on organisms and are found everywhere on the planet the planet

play a major role in recycling essential play a major role in recycling essential elementselements

source of nutrients and some carry out source of nutrients and some carry out photosynthesisphotosynthesis

benefit society by their production of benefit society by their production of food, beverages, antibiotics and vitaminsfood, beverages, antibiotics and vitamins

causative agents of some important causative agents of some important diseasesdiseases

What is Microbiology?What is Microbiology?

generally defined as the study of generally defined as the study of organisms too small to be clearly organisms too small to be clearly seen by the unaided eye (i.e.,seen by the unaided eye (i.e., microorganismsmicroorganisms))

these organisms are relatively simple these organisms are relatively simple in their construction and lack highly in their construction and lack highly differentiated cells and distinct differentiated cells and distinct tissuestissues

Members of the Microbial Members of the Microbial WorldWorld

procaryotic cells procaryotic cells lack a true lack a true membrane-delimited nucleus membrane-delimited nucleus

eucaryotic cells eucaryotic cells have a membrane-have a membrane-enclosed nucleus, are more complex enclosed nucleus, are more complex morphologically and are usually morphologically and are usually larger than procaryotic cellslarger than procaryotic cells

ProcaryotesProcaryotesmost are single-celledmost are single-celledmost have peptidoglycan in cell wallmost have peptidoglycan in cell wallcan survive broad range of can survive broad range of

environmentsenvironmentsmost are non-pathogenic and play most are non-pathogenic and play

major role in nutrient recyclingmajor role in nutrient recycling

………….. .. EucaryotesEucaryotes

animals, plants and eucaryotic animals, plants and eucaryotic microorganismsmicroorganisms

microorganisms include microorganisms include protists protists (unicellular algae, protozoa, slime (unicellular algae, protozoa, slime molds and water molds) and fungi molds and water molds) and fungi

most are larger than procaryotic cells most are larger than procaryotic cells

………….. Viruses.. Viruses

acellularacellularsmallest of all microbes (smallest is smallest of all microbes (smallest is

10,000 times smaller than a typical 10,000 times smaller than a typical bacteriumbacterium

Importance of MicroorganismsImportance of Microorganisms

first living organisms on planetfirst living organisms on planetlive almost everywhere life is live almost everywhere life is

possiblepossiblemore numerous than any other kind more numerous than any other kind

of organismsof organismsglobal ecosystem depends on their global ecosystem depends on their

activitiesactivitiesinfluence human society in many influence human society in many

waysways

Discovery of MicrobesDiscovery of Microbes

Antony van Leeuwenhoek (1632-1723)Antony van Leeuwenhoek (1632-1723)first person to observe and first person to observe and

describe microorganisms describe microorganisms accuratelyaccurately

Developed early microscopeDeveloped early microscopeFirst to First to

observemicrobes:“animalculesobservemicrobes:“animalcules””

………….. .. The Conflict over Spontaneous Generation

Spontaneous generation: living organisms can develop from nonliving or decomposing matter

1. Francesco Redi (1626-1697):•disproved spontaneous generation for large animals•showed that maggots on decaying meat came from fly eggs

2. John Needham (1713-1781):•his experiment : mutton broth in flasks boiled sealed with cork :• broth became cloudy & contained microorganisms

3. Lazzaro Spallanzani (1729-1799):

•his experiment: boiled seeds in flasks & water sealed boiled:

•no growth of microorganisms in sealed & open flasks had animicules

………….. .. Louis Pasteur (1822-1895)4. Pasteur

• Mid to late-1800s• French chemist and a “founder” of the modern science of microbiology• Settled the Spallanzani-Needham debate with the “swan-necked flask” experiment & put to rest the Spontaneous generation theory

•boiled the solutions & left flasks exposed to air•results: no growth of microorganisms•placed nutrient solution in flasks with long, curved necks

…………....PasteurPasteur

………….. .. PasteurPasteur

………….. .. PasteurPasteur

• Pasteur laid the foundation of aseptic techniques, techniques that prevent contamination by unwanted microbes. These techniques are based on Pasteur’s idea that microbes can be killed by heat and that procedures can be designed to inhibit the access of airborne microbes to nutrient environment.

• He dispprove the idea that microorganisms spontaneously generated from non-living matter through mystical forces is one of the greatest contributions of Pasteur in science

Final Blow to Theory of Spontaneous Generation

5.5. John Tyndall (1820-1893):

•demonstrated that dust carries microorganisms

•showed that if dust was absent, nutrient broths remained sterile, even if directly exposed to air

•Demonstrated directly that the growth of microbes in contaminated flasks was due to microbial cells from airborne dust particles, not from spontaneous generation

Theory of biogenesis Vs Spontaneous generation :•The theory of biogenesis states that living things can only arise from living things and cannot be spontaneously generated. •The Spontaneous generation hypothesis proposed by scientists to explain the origin of the “animalcules” observed by Antoni van Leeuwenhoek in his magnifying lenses had received wide acceptance all over Europe from Antoni’s time until the time of Louis Pasteur.

The Golden Age of Microbiology (1857-1914)

•Many disease producing organisms were discovered•Microbial metabolism studies undertaken•Microbiological techniques refined•A better understanding of the role of immunity and ways to control and prevent infection by microbes

The Role of Microorganisms in Disease

• was not immediately obvious• establishing connection depended on development of techniques for studying microbes• once established, led to study of host defenses - immunology

Recognition of the Relationship between Microorganisms and

Disease Agostini Bassi (1773-1856):

showed that a disease of silkworms was caused by a fungus

M. J. Berkeley (ca. 1845):demonstrated that the great Potato Blight of Ireland was caused by a water mold

Heinrich de Bary (1853):showed that smut and rust fungi caused cereal crop diseases

Louis Pasteur :showed that the pébrine disease of silkworms was caused by a protozoan

Other evidencesOther evidences

Joseph Lister: •provided indirect evidence that microorganisms were the causal agents of disease

•developed a system of surgery designed to prevent microorganisms from entering wounds as well as methods for treating instruments and surgical dressings

•his patients had fewer postoperative infections

Robert Koch (1843-1910)

Robert Koch:

• Established the relationship between Bacillus anthracis and anthrax

•Develop the Koch’s postulates:

used today to establish the link between a particular microorganism and a particular disease

..Koch Postulates..Koch Postulates

1.Similar pathogen must be present in every case of the disease.2. The pathogen should be isolated from the diseased animal host and grown in pure culture.3. A healthy laboratory animal inoculated with the pathogen taken from the pure culture must acquire the disease.4. The pathogen must be isolated from the inoculated animal and should be the same from the microbe in the original animal.

The Development of The Development of Techniques for Studying Techniques for Studying

Microbial PathogensMicrobial PathogensKoch’s work led to discovery or Koch’s work led to discovery or

development of:development of:agaragarpetri dishpetri dishnutrient broth and nutrient agarnutrient broth and nutrient agarmethods for isolating microorganismsmethods for isolating microorganisms

Immunological Studies

Edward Jenner (ca. 1798)

•used a vaccination procedure to protect individuals from smallpox

Pasteur and Roux :

•discovered that incubation of cultures for long intervals between transfers caused pathogens to lose their ability to cause disease•Pasteur and his coworkersdeveloped vaccines for chicken cholera, anthrax, and rabies

Emil von Behring (1854-1917) and Emil von Behring (1854-1917) and Shibasaburo Kitasato (1852-1931)Shibasaburo Kitasato (1852-1931)developed antitoxins for diphtheria and developed antitoxins for diphtheria and

tetanustetanusevidence for humoral immunityevidence for humoral immunity

Elie Metchnikoff (1845-1916)Elie Metchnikoff (1845-1916)discovered bacteria-engulfing, discovered bacteria-engulfing,

phagocytic cells in the bloodphagocytic cells in the bloodevidence for cellular immunityevidence for cellular immunity

The Development of Industrial The Development of Industrial Microbiology and Microbial Microbiology and Microbial

EcologyEcologyLouis PasteurLouis Pasteur

demonstrated that alcohol demonstrated that alcohol fermentations and other fermentations and other fermentations were the result of fermentations were the result of microbial activitymicrobial activity

developed the process of developed the process of pasteurization to preserve wine pasteurization to preserve wine during storageduring storage

……Additional DevelopmentsAdditional Developments

Sergei Winogradsky (1856-1953) and Sergei Winogradsky (1856-1953) and Martinus Beijerinck (1851-1931)Martinus Beijerinck (1851-1931)studied soil microorganisms and studied soil microorganisms and

discovered numerous interesting discovered numerous interesting metabolic processes (e.g., nitrogen metabolic processes (e.g., nitrogen fixation)fixation)

pioneered the use of enrichment pioneered the use of enrichment cultures and selective mediacultures and selective media

Aseptic techniquesAseptic techniques

………….. .. Pure Culture Pure Culture TechniqueTechnique

BibliographyBibliography

http://en.wikipedia.org/wiki/Scientific_method

http://www.brighthub.com/science/medical/articles/21169.aspx

https://files.kennesaw.edu/faculty/jhendrix/bio3340/home.html

Lecture PowerPoints Prescott’s Lecture PowerPoints Prescott’s Principles of Microbiology-Mc Graw Principles of Microbiology-Mc Graw Hill Co.Hill Co.