1. The Bacteria Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons

2. The Purple Bacteria, also called Proteobacteria is the largest and most physiological diverse of all bacteria

3. Bacteria Purple and Green (Anoxygenic Phototrophic Bacteria)
Cyanobacteria
Prochlorophytes
Chemolithotrophs: Nitrifying Bacteria
Chemolithotrophs: Sulfur- and Iron-Oxidizing Bacteria
Chemolithotrophs: Hydrogen-Oxidizing Bacteria
Methanotrophs and Methylotrophs
Sulfate and Sulfur-Reducing Bacteria
Homoacetogenic Bacteria
Budding and Appendaged (Prosthecate) Bacteria
Spirilla
Spirochetes
Gliding Bacteria
Sheathed Bacteria

4. Bacteria Pseudomonads Free-Living Aerobic Nitrogen-Fixing Bacteria
Acetic Acid Bacteria
Zymomonas and Chromobacterium
Vibrio and Related Genera
Facultatively Aerobic Gram-Negative Rods
Neisseria and other Gram-Negative Cocci
Rickettsias
Clamydias
Gram-Positive Bacteria: Cocci
Lactic Acid Bacteria
Endospore-Forming Gram-Positive Rods and Cocci
Mycoplasmas
High GC Gram-Positive Bacteria: “Actinomycetes”
Coryneform Bacteria
Propionic Acid Bacteria
Mycobacteria
Filamentous Actinomycetes

5. Facultatively Aerobic Gram-Negative Rods Enteric Bacteria
Gamma Purple bacteria
Gram-negative straight rods
Facultative aerobes
Nonsporulating
Motile by peritrichous flagella or nonmotile
Large number of strains have been isolated
Identification is now based on computer analysis of a large number of diagnostic tests carried out using miniaturized rapid diagnostic media kits and immunological and nucleic acid probes

6. Facultatively Aerobic Gram-Negative Rods
Butanediol-Producing, peritrichous
Enteric Bacteria Erwinia carotovora,
and its biochemical pathway for
formation of butanediol from two
molecules of pyruvate

7. Fermentation products
are the key to separate
the enteric bacteria

8. Two Broad Patterns of Fermentations
Mixed-Acid Fermenters:
Proteus
Citrobacter
Edwardsiella
Salmonella
Escherichia
Shigella
Butanediol Producers
Klebsiella
Enterobacter
Serratia
Erwinia
Hafnia

9. Facultatively Aerobic Gram-Negative Rods
A simplified key to identify
the main genera of enteric
bacteria

10. Escherichia Universal inhabitants of the intestinal tract
Play nutritional role (synthesizing vitamins)
Consume O2, render the large intestine anoxic
Some are pathogenic
Diarrhea
Children’s nurseries
Urinary infections
Enterotoxin

11. Shigella Very similar to E. coli Commonly pathogenic to humans
Gastroenteritis (bacillary dysentery)
Endotoxin
Neurotoxin
Transmitted by Food and Waterborne Routes

12. Salmonella Typhoid fever Gastroenteritis
Salmonella and Escherichia are related
The two have 45-50% of their DNA sequences in common
Usually pathogenic
Typhoid fever
Gastroenteritis
O antigen:cell wall (somatic) antigen, lipopolysaccharide
H antigen: flagellar antigen,

13. Proteus Rapid motility Production of enzyme urease Cause diseases:
Urinary tract infection
Enteritis
Kidney infection

14. Yersinia Y. pestis: causal agent of bubonic plague
Y. pseudotuberculosis: causal agent of a tuberculosis-like disease of the lymph nodes in animals (rarely in human)
Y. enterocolitica: causal agent of an intestinal infection (also occasionally systemic infections) in humans and animals

15. Neisseria and Other Gram-Negative Cocci
Beta purple bacteria
Lack of motility
Nonfermentative aerobic metabolism
Have five genera:
Neisseria (Neisseria gonorrhoeae)
Moraxella
Kingella
Psychrobacter
Acinetobacter

16. Rickettsias Gram-negative (Alpha purple) Coccoid or rod-shaped
Obligate intracellular parasites:
Typhus Fever
Rocky Mountain Spotted Fever
Q Fever (by Coxiella burnetii)
Transmitted by arthropod vectors or by aerosols (Coxiella Burnetii)
Close relationship with Agrobacterium tumefaciens
Representatives: Rickettsia, Rochalimaea, Coxiella

17. Chlamydias What are the differences between
Obligate parasites
Three species:
C. psittaci (psittacosis)
C. trachomatis (trachoma)
C. pneumoniae
probably have the simplest biochemical abilities of all cellular organisms
What are the differences between
Richettsia, Chlamydias and Viruses?

20. Gram-Positive Bacteria: Cocci
Clostridium (endospore formers)
Lactic Acid Bacteria
Most are Gram-Positive Cocci
Actinomycetes
Propionibacterium

21. Gram-Positive Bacteria: Cocci
Sarcina
Staphylococcus: facultative aerobe, produce acid from glucose both aerobically and anaerobically, low GC ratios, common parasites of human and animals, occasionally cause diseases
Micrococcus: obligate aerobe, high GC ratios.
Sarcina: obligate anaerobes, extremely acid-tolerant (pH 2). Sarcina ventriculi can grow in stomach of human, causing pyloric ulcerations
Staphylococcus

22. Gram-Positive Bacteria: Cocci: Deinococcus
Resistant to radiation and dessication
Most are bright red and pink in color
Cell walls consist of several layers
Deinococcus radiodurans are more resistant to radiation than bacterial endospore, also resistant to mutagenic chemicals.
Isolated from near atomic reactors.

24. Lactic Acid Bacteria Gram-positive Non-motile Non-sporulating
Lactic acid as a major or sole product of fermentative metabolism
Obtain energy only through substrate-level phosphorylation
Anaerobes, but aerotolerant
Homofermentative group: produces only lactic acid as sole product
Heterofermentative group: produces ethanol, CO2 and lactic acid

25. The fermentation of
glucose in homofermentative
and heterofermentative lactic
acid bacteria

26. Lactic Acid Bacteria Genera: Streptococcus Leuconostoc Pediococcus
Lactobacillus
Enterococcus
Lactococcus
All the above genera grow
in chains.
Many are used for the food
industry.

27. Lactic Acid Bacteria Picture above: Lactobacillus acidophilus
Picture in the middle:
Lactobacillus brevis
Picture on the bottom:
Lactobacillus delbrueckii

28. Endopsore-Forming Gram-Positive Rods and Cocci
Bacillus and Clostridium are better studied
Bacillus: aerobic and facultatively aerobic
B. popilliae and B. thuringiensis produce insect larvicides (biological insecticides)
Clostridium: strictly anaerobic
Some Clostridium sugar and produce butyric acid
Some Clostridium produce acetone and butanol
Some Clostridium ferment cellulose to ethanol, it is industrially significant, could be used to turn waste cellulose into motor fuel
Most produce one spore except polyendosporus

29. Endopsore-Forming Gram-Positive Rods and Cocci
B. popilliae and B. thuringiensis produce insect larvicides (biological insecticides)
Toxic parasporal crystal in B. thuringiensis

30. Endopsore-Forming Gram-Positive Rods and Cocci
Clostridum species have various spore location in the bacterial cells.
Bottom left: Clostridium cadaveris
Bottom middle: Clostridium sporogenes
Bottom right: Clostridum bifermentans

31. Formation of fermentation
products from the butyric
acid group of clostridia

32. Endopsore-Forming Gram-Positive Rods and Cocci
Sporosarcina is unique among endospore formers as the cells are cocci instead of rods.
Sporosarcina ureae can decomposes urea to CO2 and NH3. Causing pH increase

33. Mycoplasma
Microorganisms without cell walls that do not revert to walled organsims
The smallest organisms capable of autonomous growth
Resistant to osmotic pressure and penicillin
Due to lack of rigidity,
mycoplasma has various growth
morphologies. In agar, it appears
as fried egg shape

34. High GC Gram-Positive Bacteria: “Actinomycetes”
Most are gram-positive
Rod-shaped to filamentous
Aerobic
Generally nonmotile in the vegetative phase
Form a subdivision of gram-positive bacteria
Contain a large variety of bacteria:
Coryneform group of bacteria
Propionic acid bacteria
Obligate anaerobes
Actinomycetes

35. Coryneform Bacteria Gram-positive, aerobic Nonmotile, rod-shaped
Forming irregular-shaped, club-shaped or V-shaped cells
Main genera:
Corynebacterium
Arthrobacter
Corynebacterium: extremely diverse group of bacteria, including animal and plant pathogens
Arthrobacter: soil organisms, ditinguished from Corynebacterium by a cycle of development from rod to sphere and back to rod.

36. Coryneform Bacteria
Arthrobacter: soil organisms, ditinguished from Corynebacterium by a cycle of development from rod to sphere and back to rod.

37. Propionic Acid Bacteria
Gram-positive, pleomorphic
Nonsporulating rods
Nonmotile and anaerobic
Ferment lactic acid, carbohydrates and polyhydroxy alcohols
Produce propionic acid, succinic acid, acetic acid and CO2
Grow slowly
First discovered as inhabitants of Swiss cheese

39. Mycobacterium Rod-shaped Acid-alcohol fastness (due to mycolic acid)
Gram-positive, but not ready stained due to high surface lipid content
Pleomorphic (branching or filamentous)
Many form yellow carotenoid pigments
Mycobcterium tuberculosis grows slowly
Other like Mycobacterium smegmatis grows fast.

40. Mycobacterium
The fuchsin dye probably combines with the mycolic acid via ionic bonds between COO- and NH2+

41. Mycobacterium Characteristic colony morphology of mycobacterium
M. tuberculosis
M. avium

42. Filamentous Actinomycetes
A large group of filamentous bacteria
Usually gram-positive, forming branching filaments
Most form spores
Have high GC content of 63-78%
Streptomyces important
Streptomyces are primarily soil organisms
Streptomyces produces earthy odor (geosmins)
Streptomyces: most important antibiotic producers

43. Filamentous Actinomycetes
A young colony of an actinomycete of the genus Nocardia

44. Filamentous Actinomycetes
Several spore-bearing structures of actinomycetes: Streptomyces.

45. Filamentous Actinomycetes
Stages in the conversion of a streptomycete’s aerial hypha into spores (conidia)

46. Various types
of spore-bearing
structures in the
streptomycetes

47. Filamentous Actinomycetes
Typical appearance of a streptomycete growing on agar slants
The colors are due to the production of pigments

48. Filamentous Actinomycetes
Antibiotic action of soil microorganisms on a crowded plate
streptomycetes
Bacillus

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