Classification Of Microorganisms Flashcards
What are the two main classification systems?
Whittaker’s 5 Kingdom System
Woese’s 3 Kingdom System
What is Whittaker’s 5 Kingdom System?
It is based on means of nutrition
Plantar
Animalia
Fungi
Protistan
Monera
What is Woese’s 3 kingdom system?
Based on rRNA sequences
Has a dominance of microbial taxa, which contrasts Whittaker’s tree which is dominated by plants animal and fungi
Gene tree not an organism tree
Archaea
Bacteria
Eukarya
What is a more up to date analysis of the tree of life?
Eocyte hypothesis:
Eukarya evolved from within the Archaea
Suggests tree of life only has 2 primary kingdoms- Bacteria and Archaea
Extant Archaea evolved through partnership between bacteria and archaea
What makes up the fungi group?
Moulds, yeasts, mushrooms
Most fungi are aerobic, what is the exception to this?
Yeast
Anaerobic cellulolytic rumen fungi
How do moulds and mushrooms grow?
They grow as filaments
•Hyphae (Hypha singular)
•Mycelia (Mycelium singular)
Produce range of extracellular hydrolytic enzymes that depolymerize carbohydrates such as cellulose, which permits them to penetrate materials such as wood
How can fungi be classified?
By the type of spores they produce for sexual reproduction
Categories:
•Ascomycetes
•Zygomycetes
•Basidiomycetes
•Deuteromycetes
What are protozoa?
Unicellular eukaryotes
Larger than bacteria
Foraminifera that produce calcium carbonate frustules are marine protozoa
Important in organic matter decomposition
Control bacterial populations and carbon cycling by grazing
Lack chlorophyll but enter into symbiotic relationships with algae
Some are pathogenic
Some harbour symbiotic methanogens
What are algae?
Eukaryotic photosynthetic organisms
Some are unicellular
Some are filamentous or colonial
Include large multicellular organisms
Crucial role in primary productivity and mineral cycling
What is blue-green algae?
These are not related to algae. They are actually bacteria (cyanobacteria)
Chloroplasts evolved from cyanobacteria
How are algae classified?
Classified on the basis of photosynthetic pigments
•Chlorophyta (Green algae, Viridaeplantae)
•Chrysophyta (Golden brown algae, Stramenopiles)
•Phaeophyta (Brown algae, Stramenopiles)
•Rhodophyta (Red Algae)
•Pyrrophyta (Dinoflagellates, Alveolates)
•Euglenophyta (Euglenozoa)
What is the metabolism of bacteria like?
Huge metabolic diversity
Examples:
Photosynthesis
Photoautotrophy
Photoheterotrophy
Lithotrophy
Lithoheterotrophy
Lithoautotrophy
Heterotrophy
Multiple kinds of anaerobic metabolism
How has bacteria phyla expanded over the last 3 decades?
Went from 12 phyla to 92 phyla
Name some examples of bacteria?
Cyanobacteria
Planctomycetes
Green sulfur bacteria
Proteobacteria
What are the features of cyanobacteria?
Also called blue-green algae
Not algae, they are bacteria
Oxygenic photosynthetic bacteria
Morphologically diverse, but all are exclusive to 1 bacterial phylum
Evidence that they gave rise to chloroplasts in photosynthetic eukaryotes
Found mostly in hot springs
What are the features of planctomycetes?
Include- Planctomyces, Pirellula, Gemmata, Isophaera
Lack peptidoglycan in their cell wall
Free-living aquatic oligotrophs that dvide by budding
Variety of complex morphologies
Some have nuclear envelopes
Include anaerobic ammonia-oxidising bacteria (they oxidise ammonia using nitrogen, producing nitrogen gas)
What are the features of green sulfur bacteria?
Anoxygenic photosynthetic bacteria using sulphide as the elctron donor for CO2 fixation
Common in freshwater and marine sediments, and stratified water bodies
Form external sulfur granules from sulfied oxidation
What are the 6 classes of proteobacteria?
Alphaproteobacteria
Betaproteobacteria
Gammaproteobacteria
Deltaproteobacteria
Epsilonproteobacteria
Zetaproteobacteria
What are the features/examples of alphaproteobacteria?
Examples/includes:
Diverse autotrophs and heterotrophs
Nitrite oxidising bacteria
Methane oxidising bacteria
Many nitrogen fixing bacteria
Anoxygenic photosynthetic purple non-sulfur bacteria
What are the features/examples of betaproteobacteria?
Examples/includes:
Diverse autotrophs and heterotrophs
Autotrophic ammonia oxidising bacteria- nitrosomonas, nitrosospira
Versatile contaminant-degrading bacteria- ralstonia, burkholderia, comamonas
Perchlorate reducers- dechloromonas, dechlorosoma
What are the features/examples of gammaproteobacteria?
Examples/includes:
Diverse autotrophs and heterotrophs
Nitrite oxidising bacteria- nitrococcus
Ammonia oxidising bacteria- Nitrosococcus
Methane-oxidising bacteria- methylococcus, methylobacter
Chemolithotrophic sulfur bacteria- beggiatoa, thioploca, achromatium
Versatile metal reducing bacteria- shewanelle
Versatile contaminant degrading bacteria- Pseudomonas
Anoxygenic photosynthetic purple sulfur bacteria
What are the features/examples of deltaproteobacteria?
Examples/includes:
Diverse autotrophs and heterotrophs
Most sulfate reducing bacteria- desulfovibrio, desulfobacter, desulfobacterium, desulfococcus, desulfobulbus
Many iron reducing bacteria- geobacter
What are the features/examples of epsilonproteobacteria?
Examples/includes:
Diverse autotrophs and heterotrophs
Chemolithotrophic sulfur bacteria- thiovulum, sulfuricurvum, arcobacter, sulfurovum
Ectosymbionts of Alvinella pompejana
Gut pathogens- helicobacter, campylobacter
How many Archaea phyla were known up until recent years?
2
Euryarchaeota
Crenarchaeota
What sub groups fall under the Euryarchaeota?
Methanogens
Extreme halophiles
Thermoplasmatales
Thermococcales
Archaeoglobales
What sub groups fall under the Crenarchaeota?
Extreme thermophiles
Acidophilic thermophiles
Novel uncultured mesophiles
What are some examples of and the properties of methanogens?
E.g: Methanosarcina barkeri
Methanococcus jannaschii
Methanopyrus
Methanosaeta
Properties:
-Obligate anaerobes (killed by normal atmospheric concentrations of oxygen)
-Unique metabolism
-Utilise only simple substrates- e.g acetate, methanol, hydrogen, methylamines, CO2
How many Archaea phyla have now been described?
Over 25
What are some examples of euryarchaeota?
Thermoplasma
Thermococcus
Archaeoglobus
What are some examples of crenarchaeota?
Pyrodictum occultum
Sulfolobus spp
What are viruses, what is their structure, what are their mechanisms?
-Non-cellular
-Made from DNA or RNA, with a protein coat, some encapsulated in a membrane
-Reproduce by hijacking the nucleic acid and protein replication and synthesis systems of host cells
-Viruses that infect bacteria are called bacteriophage
-More than 5000 viral genomes in 100 litres of sea water
-Involved in control of bacteria populations
-Release and recycling of organic matter by cell lysis
-May be involved in modulating release of important trace gases from algae blooms
What are the two Life cycles bacteriophages follow?
The lytic cycle (viruses replicating using host cells)
Lysogeny (incorporation of nucleic acid into genome)
How do viruses use transduction to prey on photosynthetic organisms?
Marine cyanobacteria account for about 25% of global photosynthesis
Viruses that infect these cyanobacteria carry genes involved in photosynthesis
These genes include psbA and psbD genes which encode the vital photo system II reaction centre proteins D1 and D2
The D1 protein is the most labile protein in photosystem II and rate limiting for photosynthesis
During the lytic cycle phage must have an energy source to lyse their host- they need to maintain photosynthesis
Viral infection shuts down expression of host genes
Virus encoded D1 proteins are expressed during the infection cycle ensuring that photosynthesis is maintained
Providing the energy for viral production
