View
223
Download
1
Category
Tags:
Preview:
Citation preview
Bacteria
Unicellular Prokaryotic Cell walls contain peptidoglycan Have many shapes Generally reproduce by binary fission Obtain nourishment from organic or inorganic
substances of photosynthesis
Archaea
Prokaryotic cells Cell walls lack peptidoglycan (if present) Not known to cause human disease Mainly found in extreme environments
Fungi
Eukaryotes May be multicellular or unicellular May reproduce sexually or asexually Obtain nourishment by absorbing organic
material from their environments Cell walls composed of chitin
Protozoa
Eukaryotes Unicellular Classified by type of movement May live as free entities or parasites May reproduce sexually or asexually
Algae
Photosynthetic eukaryotes May produce sexually or asexually May be unicellular or multicellular Cell walls composed of cellulose
Viruses
Acellular organisms Composed mainly of protein and nucleic
acid; may contain lipids Obligate intracellular parasites
6 processes that define life
1. growth2. reproduction & heredity3. metabolism4. movement and/or irritability5. capacity to transport substances into & out
of cell6. cell support, protection & storage
mechanisms
History of Microbiology
Supernatural Miasma theory- disease is caused by an
altered chemical in the air Zaccharias Jansen created the first
microscope (1600). No technology prior to this
Modification of Microbe Definition
Thiomargarita nambiensis- large enough to be seen without a microscope
Viruses and prions- not living organisms
Microbes are easier to study
Microorganisms are easier to study than macroorganisms (organisms visible with the naked eye) because of – Relative simplicity– Rapid reproduction– Adapatility
History of Microbiology
Antoni van Leeuwenhoek- discovered “animalcules”
Robert Hooke- (1678)- developed the compound microscope; confirmed Leeuwenhoek’s findings; marked the beginning of the cell theory
Spontaneous Generation
Spontaneous generation- theory that living things arise from nonliving things
Debate of this theory
Francesco Redi
In his experiment, he used 3 jars containing meat and left the jar open. He took 3 other jars containing meat and sealed them. Days later, only the open jar contained organisms. Opponents said sealing the jar prevented fresh air to enter, therefore, microbes could not grow. He modified his experiment using a mesh gauze, which was thin enough to allow air, but prevent microbes.
John Needham
Boiled nutrient broth and placed them into sealed containers. Days later, microbes grew.
What are some reasons this may have happened?
Lazarro Spallanzani
In his experiment, he sealed flasks of nutrient broth then boiled them. He transferred the broth into sealed containers and no microbes grew. Needham suggested the “vital force” needed for microbes to grow was kept out of the flask by the seals
Laurent Lavosier
Showed importance of oxygen to life. Spallanzani opponents claimed there wasn’t enough oxygen to support life in his sealed flasks
Shultz and Schwann
Thought air was the source of microbes. The passed air through chemicals into heat treated flasks. No microbes grew. Opponents said the chemicals prevented microbial growth
Louis Pasteur
Louis Pasteur resolved the debate of spontaneous generation. He set up flasks with beef broth, boiled them and left them open. Other flasks containing boiled beef broth were sealed. A few days later, microbes were present in the open flasks, but not the sealed ones. Pasteur suggested that microbes are present in the air and are capable of contaminating non living solutions. Then, he set up another series of flasks with boiled beef broth containing an S shaped opening. A few days later, no microbes were present.
Louis Pasteur
These S shaped flasks allowed air to enter (filling the oxygen requirement), but prevented microbes from entering (they are presumably “caught” in the S shaped openings). He showed microbes are present in air and can contaminate sterile solutions, but the air itself does not create microbes. He also showed these microbes can be destroyed by heat or microbial access can be blocked. These discoveries formed the basis of aseptic techniques- techniques used to prevent microbial contamination
Louis Pasteur
Showed microbes caused fermentation & spoilage
Disproved spontaneous generation of m.o.
Developed aseptic techniques.
Developed a rabies vaccine.
(1822-1895)
The Golden Age of Microbiology (1857-1914)
During this time rapid advances in microbiology were made and spearheaded by Pasteur and Robert Koch
Were possible due to advances in microscopy and other technology of the Industrial Revolution
Germ Theory of Disease
Many diseases are caused by the growth of microbes in the body and not by sins, bad character, or poverty, etc.
Aseptic Techniques
Ignaz Semmelweis showed that physicians who do not disinfect their hands can transmit disease to patients.
Joseph Lister began using phenol as a disinfectant. The number of deaths from childbirth fever decreased.
Robert Koch
Robert Koch (1876) set out to discover the causative agent of anthrax. He took a sample of blood from cattle that died of anthrax and cultured it. Samples from the culture were then injected into healthy animals. After these animals became sick and died, he isolated the bacteria in their blood and cultured it. He found that both sets of organisms were identical. This experiment established a sequence of steps for relating a specific organism to a specific disease. These steps are known as Koch’s postulates
Koch’s Postulates
1) the same pathogen must be present in every case of disease
2) pathogen must be isolated from diseased host and grown in pure culture
3) pathogen from pure culture must cause disease when inoculated into a healthy susceptible laboratory animal
4) pathogen must be isolated from inoculated animal and must be shown to be the original organism
Robert Koch
Established a sequence of experimental steps to show that a specific m.o. causes a particular disease.
Developed pure culture methods.
Identified cause of anthrax, TB, & cholera.
(1843-1910)
Edward Jenner
Edward Jenner (1796) discovered from milkmaids that those who contracted cowpox became mildly ill, but never contracted smallpox. Jenner decided to determine the validity. He obtained permission to use an 8 year old “volunteer” and inoculated him with scrapings from cowpox pustules. The child became ill, but never got smallpox. This process was termed vaccination. Protection from the disease or recovery from the disease is called immunity.
Louis Pasteur
Pasteur (1880) found that aged microbes also confer immunity. He was working on isolating the causative agent of cholera using chickens. He inoculated chickens with cholera and they became sick and died. Allegedly, he went away for the summer, and his cholera samples aged. When he came back, he used these aged cultures to inoculate the chickens. These chickens became mildly ill but did not die. Then (allegedly) he inoculated these same chickens with a regular strength batch since he ran out of new chickens. He found that these chickens did not get sick at all. He determined these aged cultures lost the ability to cause disease and was able to confer immunity.
Magic Bullet
Paul Ehrlich (1910) speculated about a “magic bullet”, a chemical which could destroy a pathogen without affecting the host. Prior to this, the only chemical being used was quinine, to treat malaria. Ehrlich eventually discovered salvarsan, effective against syphilis.
Alexander Fleming
(1928), while doing experiments, left a Petri dish which became contaminated by mold. He noted an area of inhibition around the mold, an area where no bacterial growth occurred. However, the usefulness of this mold, used to produce penicillin, did not occur until the 1940s.
Types of Study
Bacteriology- study of bacteria Mycology- study of fungi Parasitology- study of parasites Immunology- study of the immune system Virology- study of viruses Phycology (algology)- study of algae Protozoology- study of protozoa
Emerging Infectious Disease
EID’s may occur due to:– evolutionary changes to existing organisms– spread of diseases to new geographic regions – increased human exposure to new diseases in areas undergoing
ecological change (construction, deforestations) – increased number of patients with depressed immune systems – disruptions in human population, such as crowding or immigration – lack of immunization – lack of nourishment– mass production and packaging of food – animal migration
People Involved in Classification
Charles Darwin (1859) proposed the theory of natural selection
Carolus Linnaeus (1735-1759)- divided organisms into plant and animal and created a 2 name system
Carl von Nageli (1857)- proposed bacteria and fungi be placed into the plant kingdom
Ernst Haeckel (1866)- proposed kingdom Protista to include bacteria, protozoa, algae and fungi; Fungi were placed into their own kingdom in 1959
Robert G. E. Murray (1968)- proposed the kingdom Prokaryotae
Evolution- living things change gradually over millions of years
Changes favoring survival are retained & less beneficial changes are lost.
All new species originate from preexisting species.
Closely related organism have similar features because they evolved from common ancestral forms.
Evolution usually progresses toward greater complexity.
Naming micoorganisms
Binomial (scientific) nomenclature Gives each microbe 2 names
– Genus - noun, always capitalized– species - adjective, lowercase
Both italicized or underlined– Staphylococcus aureus (S. aureus)– Bacillus subtilis (B. subtilis)– Escherichia coli (E. coli)
More Classification
Robert Whittaker (1969)- proposed a 5 kingdom system– Monera (Prokaryotae)- bacteria– Protista-protozoa and algae– Fungi-yeasts, molds– Plantae-plants– Animalia-vertebrates, invertebrates
Carl R. Woese (1978) proposed 3 domains to be placed above kingdom
Taxonomy - system for organizing, classifying & naming living things
Domain - Archaea, Bacteria & Eukarya Kingdom - 5 Phylum or Division Class Order Family Genus species
3 domains
Eubacteria -true bacteria, peptidoglycan Archaea –odd bacteria that live in extreme
environments, high salt, heat, etc Eukarya- have a nucleus, & organelles
Methods of Classifying and Identifying Microbes
Chapter 4 pgs 107-108 Bergey’s Manual of Determinative Bacteriology Morphological Characteristics Differential Staining Biochemical Tests Serology DNA base composition Using rRNA sequencing,
Scientific Method
Form a hypothesis - a tentative explanation that can be supported or refuted by observation & experimentation
A lengthy process of experimentation, analysis & testing either supports or refutes the hypothesis.
Results must be published & repeated by other investigators.
Scientific Method
If hypothesis is supported by a growing body of evidence & survives rigorous scrutiny, it moves to the next level of confidence - it becomes a theory
Evidence of a theory is so compelling that the next level of confidence is reached - it becomes a Law or principle
Recommended