1. Bacteria: Classification
Classification: Placing organisms in groups of related species. Lists of characteristics of known organisms.
Based on shape
cell wall structure and Gram stain
cellular respiration
Growth factors (Energy Source and Nutrient Source)
Based on Temperature
Based on PH

2. Classify based on Shape
Coccus – spherical, round, or ovoid
Bacillus – rod-shaped
Spirillum – spiral-shaped
Vibrio – comma-shaped
Spirillum bacterial classification

3. Coccus Spirillum Coccobacillus Spirochete Bacillus Pleomorphic Vibrio
Stiff
Coccus
Spirillum
Flexible
Coccobacillus
Spirochete
Bacillus
Slightly curved rods
Pleomorphic
Vibrio

4. Some are: Round – cocci Streptococci – chains
Staphlococci – in groups or clusters
Diplococci – in pairs
Micrococci
Strep
Staph

5. Some are: Rod– bacillus Streptobacilli – chains
Staphlobacilli – in groups or clusters
Diplobacilli – in pairs

6. Cocci Summary

7. Rods: Straight
E. coli

8. Gram Negative Rod Summary

9. Spirillum

10. Spiral Forms

11. Spirochetes

12. Classify based on Gram stain
Gram positive or Gram negative
The stain is named for H. C. J. Gram, a Danish physician who invented it in 1884.

13. The Gram stain, which divides most clinically significant bacteria into two main groups, is the first step in bacterial identification. 
Bacteria stained purple are Gram + - their cell walls have thick petidoglycan and teichoic acid.
Bacteria stained pink are Gram – their cell walls have have thin peptidoglycan and lipopolysaccharides with no teichoic acid.

14. In Gram-positive bacteria, the purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell. In Gram-negative bacteria, the outer membrane of ipopolysaccharides prevents the stain from reaching the peptidoglycan layer. The outer membrane is then permeabilized by acetone treatment, and the pink safranin counterstain is trapped by the peptidoglycan layer.

21. Classification of Bacteria
Gram + cocci Gram - bacilli

22. Classification of Bacteria
Gram + bacilli

23. Examples of Gram Positive bacteria
Streptococcus pyogenes - causes strep throat
Staphylococcus aureus - causes skin infections and may be responsible for boils

24. Examples of Gram Negative Bacteria
Treponema pallidum - causes syphilis
Escherichia coli - may cause severe gastrointestinal problems

25. Atypical Cell Walls
Some bacterial groups lack typical cell wall structure
Mycobacterium and Nocardia
Gram-positive cell wall structure with lipid mycolic acid
pathogenicity
high degree of resistance to certain chemicals and dyes
basis for acid-fast stain
Some have no cell wall
Mycoplasma
cell wall is stabilized by sterols
pleomorphic

26. Classifying Bacteria by Cellular Respiration
Ability to grow with / without air
Aerobic bacteria, or strict aerobes - require oxygen
Anaerobic bacteria, or strict anaerobes - cannot tolerate oxygen
Facultative anaerobics – are generally aerobes, but have the capacity to grow in the absence of oxygen
Examples of Bacteria Classified by Cellular Respiration:
Aerobic:
Bacillus cereus
Anaerobic:
Clostridium spp. ( botulism, tetanus)
Facultative anaerobes:
Staphylococcus spp.

28. Classifying Bacteria by Growth Factors
Under this scheme, they are generally classified according to:
Energy source
Nutrient source
Energy Source
Chemotroph – chemical compounds as an energy source (most pathogenic bacteria are chemotrophs.)
Phototroph - light as energy source
Nutrient Source
Heterotroph – derive carbon from preformed organic nutrients such as sugar (most pathogenic bacteria are heterotrophs.)
Autotroph – derive carbon from inorganic sources such as carbon dioxide

29. 1. Temperatures Minimum temperature Maximum temperature
lowest temperature that permits a microbe’s growth and metabolism
Maximum temperature
highest temperature that permits a microbe’s growth and metabolism
Optimum temperature
promotes the fastest rate of growth and metabolism

30. Temperature Adaptation Groups
Psychrophiles
optimum temperature 15oC
capable of growth at oC
Mesophiles
optimum temperature 40oC
Range 10o - 40oC (45)
most human pathogens
Thermophiles
optimum temperature 60oC
capable of growth at oC
Hyperthermophiles
Archaea that grow optimally above 80°C
found in seafloor hot-water vents

31. 3. pH The pH Scale Ranges from 0 - 14 pH below 7 is acidic
[H+] > [OH-]
pH above 7 is alkaline
[OH-] > [H+]
pH of 7 is neutral
[H+] = [OH-]

32. 3. pH Acidophiles Neutrophiles Alkaphiles
optimum pH is relatively to highly acidic
Neutrophiles
optimum pH ranges about pH 7 (plus or minus)
Alkaphiles
optimum pH is relatively to highly basic

34. Stress Test
The slower the pictures move, the better your ability of handling stress. Alleged criminals that were tested see them spinning around madly; however, senior citizens and small children see them standing still. None of these images are animated - they are perfectly static.