2. Microbilogy bacteria bacteriophage algae spirochaetes protozoaviruses cyanobacteria fungi

3. Single-celled organisms and some non-cellular parasites What are microbes? Microbiology study of organisms too small to be seen by the naked eye

4. Microorganisms (mo’s) are able to carry out life processes of growth, energy generation, and reproduction in a single cell. Mo’s are unicellular, small and reproduced by fission (asexually) 99% of the mo’s cannot be cultured in the lab Specifically, they have the ability to: –grow on different substances –withstand variation in temperature –withstand variation in barometric pressure –withstand osmotic pressure –withstand changes in pH

5. Microbial ubiquity… MO’s exist everywhere! They are in the soil, water, your skin and hair, your gastrointestinal tract, and even on or in your food. Yet we are barely aware that they exist. We become aware when we become sick, see spoiled food or damaged goods. However, the sheer minority (much less than 1%) cause disease. Most are beneficial to man and the biosphere of the earth.

6. They’re (almost) everywhere! An overview of prokaryotic life Prokaryotes were the earliest organisms on Earth (>3.5 bya) and evolved alone for 1.5 billion years. Today, prokaryotes still dominate the biosphere. Their collective biomass outweighs all eukaryotes combined by at least tenfold. More prokaryotes inhabit a handful of fertile soil or the mouth or skin of a human than the total number of people who have ever lived.

7. Microbes exist in huge numbers! For example, for bacteria –10 times as many microbial cells as human cells on/in body –10 9 /gram of soil; 10 3 -10 4 different populations –10 11 / gram in intestinal tract –10 5 /ml in groundwater –10 4 /ml in ocean

8. Amazing But True More bacteria in our bodies than human cells! More different types of bacterial genes in our body then there are human genes! “The second human genome project” (David Relman)

9. What Microbiologists Do ??? Work in almost every industry - from food, agriculture and pollution control to biotechnology, pharmaceuticals and health, government agencies and labs, in education as teachers and researchers. No one microbiologist can study everything! That's why people who become microbiologists usually focus on a particular microbe or research area. –Bacteriologists focus on bacteria. –Virologists specialize in viruses. –Mycologists study fungi. –Epidemiologists track down outbreaks of disease –Immunologists study how the body defends itself against microbial invaders?

10. Fields of Microbiology

11. 10 Characteristics of Cells Eucaryotic cells: animals, plants, fungi, and protists –contain double-membrane bound nucleus with DNA chromosomes –contain membrane-bound organelles that compartmentalize the cytoplasm and perform specific functions Procaryotic cells: bacteria and archaea –no nucleus or other membrane-bound organelles

12. The size and cell type of microbes MicrobeApproximate range of sizes Cell type Viruses 0.01-0.25 µ m Acellular Bacteria 0.1-10 µ m Prokaryote Fungi 2 µ m->1m Eukaryote Protozoa 2-1000 µ m Eukaryote Algae 1 µ m-several meters Eukaryote

13. Size of Microbes Microbes vary in size ranging from 10 nm (nanometers) to 100 mu (micrometers) to the macroscopic. Viruses in nm = 10 -9 m (meter) Bacteria in um = 10 -6 m Helminths in mm = 10 -3 m

14. Relative sizes of microbes

15. The power of microbe lies in its speedy growth Imagine the weight of biomass of E.coli after 24 hrs under optimal growth?

16. Bacteria Reproduction Asexual, through binary fission No true sexual reproduction, since neither mitosis nor meiosis exist in prokaryotes Horizontal transfer of genetic material Transformation Transduction Conjugation Direct transfer of genetic material from one prokaryote to another

17. B inary fission E. coli DNA cell wall

18. Conjugation in E. coli Sex pilus Sex pilus connects cells and draws them together Conjugation tube then forms

19. Kinds of microbes Non-cellular, parasitic molecules Viruses Viroids Prions Prokaryotes Domain Bacteria Domain Archaea Eukaryotes Several Kingdoms in Domain Eukarya

20. Classification of Microbes Based primarily on genetic sequence data; e.g., small subunit ribosomal RNA – present in all organisms NOTE: “Microbes” and “Prokaryotes” are not taxonomic categories

21. Bacteria  Prokaryotes  Peptidoglycan cell walls  Binary fission  Ex: Escherichia coli

22. Cyanobacteria

23. Archaea  Prokaryotes  Lack peptidoglycan  Live in extreme environments (extremophiles) Include:  Methanogens  Extreme halophiles  Extreme thermophiles

24. Archaebacteria

25. Algae  Eukaryotes  Cellulose cell walls  Photosynthetic  Produce molecular oxygen and organic compounds  Part of food chain

26. Fungi  Eukaryotes  Chitin cell walls  Molds and mushrooms are multicellular  Yeasts are unicellular

27. Protozoa  Eukaryotes  Mostly saprobes and commensals  May be motile by means of pseudopod, cilia or flagella

28. Viruses  Acellular  Obligate intracellular parasites  Genome consist of DNA or RNA called Core  Core surrounded by protein coat called Capsid  Virion may be enclosed in lipid envelope

29. Nonliving parasitic molecules Viruses Single or double stranded RNA or DNA with a protein coat Common cold, Ebola, HIV HIV

30. Nonliving parasitic molecules Viruses Single or double stranded RNA or DNA with a protein coat Common cold, Ebola, HIV Viroids Short, single strand of RNA w/o protein coat Primarily infect plants Prions Protein particles w/o genetic material Kuru, mad cow, chronic wasting disease

31. Differences between bacteria and viruses Viruses –Obligate intracellular parasites –No ribosomes –DNA or RNA, not both –seen by EM –10-100s of genes –Tangled phylogeny Bacteria –Usually free-living, but can be parasites –Ribosomes –DNA and RNA –seen by LM –100s-1000s of genes –Natural phylogeny

32. Nutritional Patterns