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Introduction to microbiology

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1 Introduction to microbiology
Introduction to microbiology. Classification and nomenclature of microorganisms.


3 Course Introduction Instructor: Dr Elena Romancenco
Department of Microbiology, Virology and Immunology WEBSITE:

4 Course objectives List major groups of microorganisms and their habitats. Overview and history of Microbiology. Describe the system of scientific nomenclature used to name microorganisms.

5 Definition Microbiology (mikros bios logos – small, live, study) study microorganisms and their activities. Microbiology is the study of microorganisms usually less than 1mm in diameter which requires some form of magnification to be seen clearly. Microbiology - study the organisms that can exist as single cells, contain a nucleic acid genome for at least some part of their life cycle, and are capable of replicating that genome themselves or getting replicated with the help of host cells

6 Branches of Microbiology
Bacteriology: study of bacteria Mycology: study of fungi Virology: study of viruses Beijerinck, NE: discovered intracellular reproduction of TMV; coined the term “virus” (1899) Parasitology: study of protozoa and parasitic worms

7 Branches of Microbiology
Immunology: study of immunity Edward Jenner, UK: developed vaccination (1798) Metchnikoff, RU: discovered phagocytes (1884) Paul Ehrlich, DE: theory of immunity (1890) Chemotherapy Treatment of disease by using chemical means Antibiotics produced naturally Synthetic drugs Paul Ehrlich (1878) – used arsenic compounds to fight disease

8 Branches of Microbiology
Chemotherapy Alexander Fleming, Scotland (1928) discovered penicillin Selman Waksman, Ukraine (1944) discovered streptomycin Problems Toxicity of drugs => Selective toxicity Resistance of bacteria to drugs

9 Affect our lives in many different ways.
Microorganisms are everywhere, but why is so important to learn about them? Affect our lives in many different ways.

10 Microbes are capable of growing in a wide variety of environments.
Bacteria will grow in frigid glaciers to boiling volcanic springs, dry sands to the open ocean.


Microorganisms are the oldest forms of life. Nutrient production & energy flow Production of foods Decomposition (bioremediation) Without certain microorganism life could not exist; produce O2 and N2 Production of drugs & vaccines Genetic engineering Causing disease Microorganisms have killed more people than have ever been killed in war.

13 Why Study Medical Microbiology?
The majority of serious diseases in humans (especially those of early childhood) are due to microbial infections. Prior to the discovery of antibiotics and vaccines, a large proportion of children died before adulthood because of infectious disease. Till 1900, the average life expectancy in the United States was 40 years of age. In years, largely due to the near eradication of most serious early childhood diseases. This trend is seen in the gap between developed and developing countries in terms of causes of death (mortality).

14 MICROBES MICROBES includes all those living organisms that can not be viewed (seen) in any detail by the human eye. Alternatively, a MICROBE is any living creature that must be examined with a magnifying lens in order to see its unique physical characteristics (size, shape, motility, color).

15 Microbes Pathogen or pathogenic - capable of producing disease.
Though only a minority of microorganisms are pathogenic, practical knowledge of microbes is necessary for their treatment so is highly relevant to medicine and related health sciences. Normal flora [normal microbiota] - not typically-disease-causing microorganisms normally found in and on healthy individuals. on the skin, in the eyes, in the nose, in the mouth, in the upper throat, in the lower urethra, in the lower intestine.

16 the Bacterium Escherichia coli;
a photosynthetic cyanobacterium a fungus Ebola virus the malaria parasite (a protozoan 16

17 A, Influenza virus; B, West Nile Virus; C, Staphylococcus aureus; D, Streptococcus pneumoniae.

18 Microbiologists may be interested in various characteristics or activities of microbs and may study:
Microbial morphology Microbial cytology Microbial physiology Microbial ecology Microbial genetics and molecular biology Microbial taxonomy

19 Classification of life

20 For many years, living organisms were divided into two kingdoms:
Animalia (animal) and Plantae (vegetable).

21 Classification Schemes
Two kingdoms Plantae Plantae Animalia

22 But after 1800s, scientists realized that these two kingdoms could not adequately express the diversity of life. Since the 1960s, the most widely used scheme - five kingdoms. Viruses are separate group of biological entities, although not organisms in the same sense as Eukaryotes, Archaea and Bacteria.

23 Classification schemes, 5 kingdoms
Plantae Monera Protista Plantae Fungi Animalia Prokaryotes Domain Bacteria (Eubacteria) Domain Archaea (Archaeabacteria) Eukaryotes

24 Classification of Life
3 major Domains of life Bacteria Archaea Eukaryota (Eukarya) The first two are Prokaryotes (Bacteria and Archaea)- without true nucleus, while the Eukaryotes all have a true nucleus in each cell. The 3 Domains. Source:


26 Kingdom Monera All organisms in the Kingdom Monera are prokaryotes.
lack nuclei and organelles most of their cell walls are made of peptidoglycan (the exceptions are the archaebacteria). The archaebacteria have cell walls that lack peptidoglycan, cell membranes that utilize different lipids, and ribosomes similar to those found in eukaryotes. The bacteria (eubacteria-true bacteria) are characterized by how they metabolize resources, their means of motility, and their shape. Most organisms in the Kingdom Monera reproduce through binary fission (asexual) or conjugation (sexual).

27 Bacteria Most utilize flagella for movement.
Digestion is extracellular (outside the cell) and nutrients are absorbed into the cell. Circulation and digestion in Kingdom Monera is accomplished through diffusion.

28 Bacterial Classification
by Metabolism Morphology (shape) Staining, etc

29 According the metabolism
Autotrophs manufacture their own organic compounds. Heterotrophs obtain their energy by feeding on other organic substances. Saprophytes, a special kind of heterotroph, obtain energy by feeding on decaying matter.

30 According the symbiotic relationships with other organisms:
In parasitism, harm is caused to the host. In commensalism, one organism benefits while the other is unaffected. In mutualism, both organisms benefit.

31 According the respiration:
In obligate aerobes, the prokaryotes must have oxygen to live. In obligate anaerobes, the organisms cannot survive in the presence of oxygen. And in facultative anaerobes they can survive with or without oxygen.

32 According the shapes: cocci (spherical), bacillus (rod shaped), and
spirillum (spirals).

33 Classification of bacteria
Cocci Micrococcus Staphylococci Irregular clusters of cocci Diplococci Pairs of cocci Streptococci Chains of cocci

34 Classification of bacteria
Bacilli Rod like Diplobacilli Pairs of bacilli Streptobacilli Chains of bacilli Spirochetes Spiral


36 Size of bacteria Unit of microbial measurement
 micrometers (um) 1 um being 10-6  m   or m(1/25,000 inch) nanometers  1 nm being 10-9 or m. Pathogenic bacterial species vary from approximately 0.4 to 2 um in size


38 Taxonomy Taxonomy is the classification of organisms. The most common system in use today is the Five Kingdoms: Monera (Prokaryota), Protista, Fungi, Plantae, and Animalia. Organisms in each kingdom are divided into phyla. In each phylum, organisms are separated into classes. In each class, organisms are segregated into orders. In each order, organisms are divided into families. In each family, organisms are separated by genus. And finally, in each genus organisms are divided into species. Just remember that King Philip Can Order For Genial Students.

39 Naming micoorganisms Binomial (scientific) nomenclature
Gives each microbe 2 names Genus - noun, always capitalized and may be abbreviated species - adjective, lowercase, never abbreviated A genus name may be used alone to indicate a genus group; a species name is never used alone eg: Bacillus subtilis       B. subtilis Both italicized or underlined Staphylococcus aureus (S. aureus) Bacillus subtilis (B. subtilis) Escherichia coli (E. coli)

40 Nomenclature Common or descriptive names (trivial names)
Names for organisms that may be in common usage, but are not taxonomic names eg: tubercle bacillus         (Mycobacterium tuberculosis) meningococcus (Neiserria meningitidis) Group A streptococcus (Streptococcus pyogenes)

41 Eukaryotes

42 Prokaryotes Kingdom - Monera Domain - Bacteria Phylum – Proteobacteria
Class – Gammaproteoba Order – Enterobacteriale Family – Enterobacteriace Genus – Escherichia Species – Escherichia coli

43 "The role of the infinitely small in nature is infinitely large"
Louis Pasteur

44 Historical Perspectives

45 Historical YEAR NAME ACHIEVEMENT 1st century BC Varo
Concept of “Animalia minuta” 1546 Fracostorius Contagion- Cause of syphilis 1590 Jensen Hand lens 1683 Antony van Leeuwenhoek First Microscope “Animalcules” 1678 Robert Hook Compound microscope 1745 Needham (Priest) Abiogenesis 1836 Schulze & Schwan Air contains microbes 1840 Oliver Homes, Poet physician Contageousness & Puerperal fever 1846 Ignaz Semmelweis Cause, concept & prophylaxis of child-bed fever 1853 Augustino Bassi Silk worm disease due to a fungus

46 Pioneers of Microbiology
Robert Hooke, UK (1665) Proposed the Cell Theory Observed cork with crude microscope All living things are composed of cells Spontaneous generation Some forms of life could arise spontaneously from non-living matter Francesco Redi, IT (1668) Redi’s experiments first to dispprove S.G.

47 Antonie van Leeuwenhoek
First to observe living microbes his single-lens magnified up to 300X ( )

48 Louis Pasteur (1822-1895) French chemist
Father/Founder of Modern Microbiology Fermentation – a microbiological process Beer/Wine not produced without microbes Showed microbes caused fermentation & spoilage Disproved spontaneous generation of m.o. Developed aseptic techniques. Developed a rabies vaccine. ( )

49 Louis Pasteur 1822-95 Methods & Techniques of cultivation
Introduced sterilization Tyndalization (Tyndal-1877) Studied Silkworm disease, anthrax, chicken cholera, hydrophobia. Introduced live vaccines – Jenner (Cow-pox vaccine) Antirabic vaccine Pasteur Institutes

50 Joseph Lister 1867 Prof of Surgery, Glasgow Royal Infirmatory
Introduced Antiseptic Surgery Called Father of Antiseptic Surgery

51 Robert Koch (1843-1910) German general practitioner
Perfected bacteriological techniques Isolated pure cultures of bacteria for the first time Discovered Anthrax bacilli, Cholera vibrio, M. tuberculosis Father of Medical Microbiology Hypersensitivity Established a sequence of experimental steps to show that a specific m.o. causes a particular disease. ( )


53 Highlights in the History of Microbiology
1900 Proved mosquitoes carried the yellow fever agent (Walter Reed) 1910 Discovered cure for syphilis (Paul Ehrlich) 1928 Discovered Penicillin (Alexander Fleming) 1887 Invented Petri Dish (R.J. Petri) 1892 Discovered viruses (Dmitri Iosifovich Ivanovski) 1899 Recognized viral dependence on cells for reproduction (Martinus Beijerinck)

54 Highlights in the History of Microbiology
1977 Developed a method to sequence DNA (W. Gilbert & F. Sanger) 1983 Polymerase Chain Reaction invented (Kary Mullis) 1995 First microbial genomic sequence published (H. influenzae) (TIGR)

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