Download Review of Key Microbial Groups

Review of Key Microbial Groups
A.Domain Bacteria
B.Domain Archaea
C.Domain Eucarya
Domain Bacteria:
General Features
●
Prokaryotic cell structure
–
–
●
●
DNA organized in nucleoid; no nuclear
membrane, nucleolus, or histones
No complex membranous organelles (e.g.
endoplasmic reticulum, golgi apparatus)
Cell walls containing peptidoglycan found in
most groups of bacteria
Some features of gene expression (mRNA,
tRNA, RNA polymerase, ribosomes) are
more similar to archaea; some are more
similar to eucarya
Domain Bacteria:
General features
●
Metabolic strategies found in Bacteria:
–
–
–
Chemoheterotrophy
Chemolithotrophy
Photosynthesis
Domain Bacteria:
General features
●
Cell Wall Structures in Bacteria
–
Gram-negative cell wall
●
●
●
–
Gram-positive cell wall
●
●
–
Thick layer of peptidoglycan
Teichoic acids
“Acid-fast” bacteria
●
●
–
Outer membrane containing lipopolysaccharide
Thin layer of peptidoglycan
Periplasmic space
Bacteria in Phylum Actinomycetes with high
concentrations of mycolic acid
Detected by acid-fast staining
Mycoplasmas
●
Bacteria in Phylum Firmicutes with no cell wall
Domain Bacteria:
General features
●
Other structural features found in Bacteria
–
–
–
–
–
–
–
–
Plasma membrane
Capsules
Pili or Fimbrae
Cytoplasmic inclusions
Bacterial DNA
Ribosomes
Flagella
Spores
http://science.kennesaw.edu/~jhendrix/bio3340/handouts/microcells.ppt
Domain Bacteria:
General features
●
Identification of the Bacteria
–
–
–
–
–
–
–
–
–
–
Colony morphology
Cell shape & arrangement
Cell wall structure (Gram staining)
Special cellular structures
Biochemical characteristics
Serological tests
G+C content
DNA hybridization
DNA fingerprinting
Nucleic acid sequencing
http://science.kennesaw.edu/~jhendrix/bio3340/handouts/microtaxonomy.ppt
Domain Bacteria:
Major Groups
●
Phylum Proteobacteria
–
“Gram-negative” type cell wall architecture
●
●
●
–
Outer membrane with lipopolysaccharide and porin
protein
Thin layer of peptidoglycan
Notable periplasmic space containing transport
proteins and hydrolases
A very large and metabolically diverse phylum;
various groups utilizing chemoheterotrophy (both
respiration & fermentation), chemolithotrophy,
photosynthesis
Domain Bacteria:
Major Groups
●
Phylum Proteobacteria (cont.)
–
Major groups of proteobacteria
●
●
Enterobacteriacea: “Gram-negative enterics;”
common intestinal flora and pathogens; both
respiratory and fermentative metabolisms;
facultatively anaerobic; oxidase negative; includes
genera Escherichia, Klebsiella, Enterobacter,
Citrobacter, Serratia, Proteus, Salmonella, Shigella,
Yersinia
Pseudomonadaceae: Genus Pseudomonas and
related genera; common soil and aquatic organism;
usually aerobic; oxidase positive; use EntnerDouderoff glycolysis instead of EMP glycolysis; often
can metabolize unusual carbon substrates such as
aromatic hydrocarbons
Domain Bacteria:
Major Groups
●
Phylum Proteobacteria (cont.)
–
Major groups of proteobacteria (cont.)
●
●
●
●
●
Purple nonsulfur photosynthetic bacteria, e.g.
Rhodospirillum
Green sulfur photosynthetic bacteria, e.g. Chlorobium
Nitifying bacteria: Nitrosomonas (oxidizes ammonium
to nitrite) and Nitrobacter (oxidizes nitrite to nitrate)
Nitrogen fixing bacteria: Rhizobium (symbiotic in root
nodules); Azotobacter (free-living)
Various human pathogens in phylum Proteobacteria:
Neisseria, Vibrio, Haemophilus, Rickettsia, Coxsiella,
Bordetella, Legionella, Camphylobacter, Helicobacter
Domain Bacteria:
Major Groups
●
Phylum Firmicutes
–
–
–
“Low G-C” Gram-positive bacteria
Cell walls consist of thick layers of extensively
crosslinked peptidoglycan (exception:
Mycoplasma)
Notable genera
●
●
●
Clostridium: Strictly anaerobic, spore-forming rods;
common in soil; includes botulism & tetanus;
significant contaminant in food industry & medicine
Bacillus: Facultatively anaerobic, spore-forming rods;
common in soil; frequent contaminant; includes
Bacillus anthracis
Mycoplasma: Have no cell walls; respiratory tract flora
& pathogens of humans & other animals
Domain Bacteria:
Major Groups
●
Phylum Firmicutes
–
Notable genera
●
●
●
Lactobacillus: Facultatively anaerobic
nonsporeforming rods; oral or intestinal flora; found in
sevral dairy products such as yogurt
Staphylococcus: Catalase-positive cocci; common
skin flora; virulent strains of Staph. aureus are
associated with skin infections, food poisoning, and
toxic shock syndrome
Streptococcus, Enterococcus, Lactococcus: Catalasenegative cocci; diverse group with numerous skin,
oral, and intestinal flora as well as several important
pathogens such as Streptococcus pyogenes (Group A
pyogenic strep)
Domain Bacteria:
Major Groups
●
Phylum Actinomycetes
–
–
–
“High G-C” Gram-positive bacteria
Cell walls consist of thick layers of extensively
crosslinked peptidoglycan
Notable genera
●
●
●
Corynebacterium: Facultatively anaerobic, irregular
rods; coryneform arrangement; common soil & skin
flora; common laboratory contaminant
Micrococcus: Facultatively anaerobic cocci; tetrads or
sarcinae; yellow or pink pigmentation; common soil
flora;common laboratory contaminants
Actinomyces, Streptomyces; Common soil organism;
filamentous growth often mistaken for mold
Domain Bacteria:
Major Groups
●
Phylum Actinomycetes
–
Notable genera
●
Mycobacterium: Acid-fast rods; high concentration of
mycolic acid in the cell wall make them difficult to
gram stain; certain species are skin and soil flora;
includes tuberculosis and leprosy
Domain Bacteria:
Major Groups
●
Phylum Bacteroidetes
–
–
–
A group of gram-negative, strictly anaerobic
bacteria
Most are intestinal and oral flora in humans and
animals; some are pathogens
Example: genus Bacteroides
Domain Bacteria:
Major Groups
●
Phylum Cyanobacteria
–
–
–
The “blue-green algae”
Carry out oxygenic photosynthesis
Have thylakoid membranes, chlorophyll a, and
photosystem II
Domain Bacteria:
Major Groups
●
Phylum Chlamydiae
–
–
●
A group of gram-negative, obligately intracellular
parasites
Genus Chlamydia
Phylum Spirochaetes
–
–
–
Characterized by flexible helical-shaped cells
Cells covered by an outer sheath and are motile
by a modified flagellar structure called an axial
filament
Example: Treponema pallidum (syphillis)
Domain Archaea:
General Features
●
●
●
●
Prokaryotic cell structure
Cell walls have no peptidoglycan; some
archaea have pseudomurein or other
polymers
Some features of gene expression (mRNA,
tRNA, RNA polymerase, ribosomes) are
more similar to bacteria; some are more
similar to eucarya
Metabolic strategies found in Archaea:
–
–
Chemoheterotrophy
Chemolithotrophy
Domain Archaea:
Major Groups
●
Methanogenic archaea
–
●
Extremely thermophilic archaea
–
–
●
Sulfate reducers, Archaeoglobus
Sulfur reducers, Desulfurococcus, Sulfolobus
Extremely halophilic archaea
–
●
Methanobacterium, Methanococcus
Halobacterium, Halococcus
Cell wall deficient archaea
–
Thermoplasma
Domain Eucarya:
General Features
●
●
●
●
Eukaryotic cell structure
Cell walls vary; none in “animal-like” cells;
cellulose in algae most others, with additional
polysaccharides in different groups (e.g.,
chitin in many fungi)
Some features of gene expression (mRNA,
tRNA, RNA polymerase, ribosomes) are
more similar to bacteria; some are more
similar to archaea
Metabolic strategies found in Eucarya:
–
–
Chemoheterotrophy (respiration in mitochondria)
Photosynthesis (in chloroplasts)