Pharmaceutical Microbiology - Classification of Microbes

1. Different Methods of Classification
• Linnaeus (1735) classified all living organisms into
two kingdoms
– Plantae
– Animalia
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2. Plant vs Animal cell
Cell Wall
Chloroplasts
Cell Nucleus
Organelles/ Vacuoles
Cytoplasm
Cell Membrane
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4. • Eukaryotes are organisms, including humans, whose cells have a
well-defined membrane-bound nucleus (containing
chromosomal DNA) and organelles
• Eukaryotes can be single-celled or multi-celled, such as humans,
plants, fungi, and insects
• Prokaryotic cells do not contain a nucleus or any other
membrane-bound organelle. Ex. Bacteria
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5. Prokaryotic vs Eukaryotic
Nuclear
Membrane

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7. • Whittaker (1969) proposed an elaborate five
kingdom taxonomic classification
– Monera, Protista, Fungi, Plantae and Animalia
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13. • There are various hypotheses as to the origin of
prokaryotic and eukaryotic cells
• Because all cells are similar in nature, it is generally
thought that all cells came from a common ancestor cell
termed the Last Universal Common Ancestor (LUCA)
• These LUCAs eventually evolved into three different cell
types, each representing a domain
• The three domains are the Archaea, the Bacteria, and the
Eukarya
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14. 3 Domains
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 Eubacteria
 true bacteria, peptidoglycan
 Archaea
 odd bacteria that live in extreme environments, high salt,
heat, etc. (usually called extremophiles)
 Eukarya
 have a nucleus & organelles (humans, animals, plants)

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16. The Archaea (archaebacteria)
• Archaea are prokaryotic cells
• Unlike the Bacteria and the Eukarya, the Archaea have membranes
composed of branched hydrocarbon chains (many also containing rings
within the hydrocarbon chains) attached to glycerol by ether linkages
• The cell walls of Archaea contain no peptidoglycan
• Archaea are not sensitive to some antibiotics that affect the Bacteria, but
are sensitive to some antibiotics that affect the Eukarya
• Archaea contain rRNA that is unique to the Archaea as indicated by the
presence of molecular regions distinctly different from the rRNA of
Bacteria and Eukarya
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The Bacteria and the Eukarya have membranes composed of unbranched
fatty acid chains attached to glycerol by ester linkages. The Archaea have
membranes composed of branched hydrocarbon chains attached to
glycerol by ether linkages.

18. • Archaea often live in extreme environments and
include methanogens, extreme halophiles, and
hyperthermophiles
• One reason for this is that the ether-containing
linkages in the Archaea membranes is more stabile
than the ester-containing linkages in the Bacteria and
Eukarya and are better able to withstand higher
temperatures and stronger acid concentrations
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19. The Bacteria (eubacteria)
• Bacteria (also known as eubacteria or "true bacteria") are prokaryotic cells
that are common in human daily life, encounter many more times than the
archaebacteria. Eubacteria can be found almost everywhere and kill
thousands upon thousands of people each year, but also serve as antibiotics
producers and food digesters in our stomachs.
• Bacteria are prokaryotic cells
• Like the Eukarya, they have membranes composed of unbranched fatty acid
chains attached to glycerol by ester linkages
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20. The Bacteria (eubacteria)
• The cell walls of Bacteria, unlike the Archaea and the Eukarya, contain
peptidoglycan
• Bacteria are sensitive to traditional antibacterial antibiotics but are resistant
to most antibiotics that affect Eukarya
• Bacteria contain rRNA that is unique to the Bacteria as indicated by the
presence of molecular regions distinctly different from the rRNA of Archaea
and Eukarya.
• Bacteria include mycoplasmas, cyanobacteria, Gram-positive bacteria, and
Gram-negative bacteria
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21. The Eukarya (Eucarya / Eukaryotes)
• Like the Bacteria, they have membranes composed of unbranched
fatty acid chains attached to glycerol by ester linkages
• Not all Eukarya possess cells with a cell wall, but for those Eukarya
having a cell wall, that wall contains no peptidoglycan
• Eukarya are resistant to traditional antibacterial antibiotics but are
sensitive to most antibiotics that affect eukaryotic cells
• Eukarya contains rRNA that is unique to the Eukarya as indicated by
the presence of molecular regions distinctly different from the rRNA
of Archaea and Bacteria
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22. Comparison of three cellular domains
Characteristic Features Bacteria Archaea Eukarya
Cell types Prokaryotic Prokaryotic Eukaryotic
Chromosomes Single, or few, Circular Single, Circular Several, Linear
Types of ribosomes 70S 70S, but structure is
similar to 80S
80S
Presence of unique
ribosomal RNA
signature sequences
+ + +
No. of sequences
shared with Eukarya
1 3 All
Protein synthesis
similar to Eukarya
- + +
Presence of
peptidoglycan in cell
wall
+ - -
Cell membrane lipids Fatty acids with ester
linkages
Long-chain, branched
hydrocarbons with
ether linkages
Fatty acids with ester
linkages
Sterols in membrane - (some expections) - +
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25. TAXONOMY
– Organizing, classifying and naming living things
– Formal system originated by Carl von Linné
(1701-1778)
– Identifying and classifying organisms according to
specific criteria
– Each organism placed into a classification system
– Formalised Binomial Nomenclature, the
modern system of naming organisms
– He is known as the "father of modern taxonomy"
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26. Taxonomy
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• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• species

27. Naming of micoorganisms
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Pharmacy
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• 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)

28. Species and Subspecies
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 Species
 collection of bacterial cells which share an overall similar
pattern of traits in contrast to other bacteria whose pattern
differs significantly
 Strain or variety
 culture derived from a single parent that differs in structure or
metabolism from other cultures of that species (biovars,
morphovars)
 Type
 subspecies that can show differences in antigenic makeup
(serotype or serovar), susceptibility to bacterial viruses (phage
type) and in pathogenicity (pathotype)