Insight on Bacteria and the archaea

• •Mixotrophs – able to undertake mixed modes of nutrition e.g. phototroph in light but heterotroph in dark.
• •Autotrophs – carbon in form of CO2
• Heterotrophs – carbon from carbon containing compounds
• Chemoorganotrophs obtain their energy from the oxidation of organic compounds
• Chemolithotrophs obtain their energy from the oxidation of inorganic compounds
• Phototrophs contain pigments that allow them to use light as an energy source.
• Chemoorganotroph


  Thousands of organic compounds available from glucose (natural) to DDT (synthetic).
• Chemoorganotroph


  Example - Escherichia coli
• Chemoorganotroph


  Energy obtained by removing e- (oxidising) from the compound and conserved in cell as ATP.
• Chemoorganotroph


  All can be broken down by >1 microorganism.
• Chemolithotroph


  Energy derived from inorganic compounds ( H2, Fe2+, NH4+).
• Chemolithotroph


  Only in prokaryotes - bacteria & archaea.
• Chemolithotroph


  Substrates for oxidation ( e- removal) may be waste from chemoorganotrophs.
• Chemolithotroph


  Example- Acidothiobacillus ferrooxidans
• Phototrophs


  energy derived from light
• Phototrophs


  May or may not evolve O2 in ATP generation
• Phototrophs


  Oxygenic photosynthesis - evolve O2 (cyanobacteria such as Oscillatoria spp.)

  Anoxygenic photosynthesis - no evolved O2 (purple, Thiospirillum spp. and green Chlorobium spp. bacteria)
• •Gracilicutes: contained four classes of Gram-negatives (Proteobacteria, Planctobacteria, Sphingobacteria, Spirochaeta). Attempts to revive in 2006 (Cavalier-Smith)
• •Firmicutes: typically contains two classes of Gram-positive and endospore producing (Clostridia and Bacilli)
• •Tenericutes: contains one class of bacteria(Mollicutes) which all lack rigid cell walls and include Mycoplasma
• •Mendosicutes – methanogens now  archaea
• A phylum is a group of bacteria sharing a common ancestor that diverged early from other bacteria, based on small-subunit rRNA (SSU rRNA) sequence.
• Cyano – all oxyegenic

  photosynthetics but

  diverse habitats and shape
• Spiro – unique cell structure

  but diverse habitat and

  metabolism.
• The bacteria that appear to have diverged the earliest from ancestral archaea and eukaryotes are called “deep-branching”.
• Deep-Branching Thermophiles


  Show the fastest doubling rates of all cells, as well as high rates of mutation
• Phylum: Proteobacteria


  Alpha, Beta, Gamma, Delta and Epsilon
• Proteobacteria


  Escherichia coli is in gamma
• Proteobacteria


  Purple bacteria, pseudomonads, enteric bacteria, acetic acid bacteria, budding, stalked bacteria, myxobacteria, rhizobia
• Subgroup- Gamma Proteobacteria


  contains many pathogens- Yersinia, Vibrio, Pseudomonas

  Inclusion /exclusion in flux
• Subgroup: Gamma Proteobacteria

  VAAP clade (Vibrionales, Aeromonadales, Alteromonadales, Pasteurellales)
• Subgroup: Delta Proteobacteria

  Contains most of the known sulfate- (Desulfovibrio, Desulfobacter, Desulfococcus,

  Desulfonema, etc.) and sulfur-reducing bacteria (e.g. Desulfuromonas spp.)

  alongside several other anaerobic bacteria with different physiology (e.g.

  ferric iron-reducing Geobacter spp. and syntrophic Pelobacter and Syntrophus spp.)
• Subgroup: Epsilon Proteobacteria

  •Microaerophilic and found in stomach•Implicated in many ulcers, cancers of stomach but 80% of infected individuals are asymptomatic•Discovered 1982 by Barry Marshall and Robin Warren (Nobel Prize in Physiology & Medicine in 2005)

  • Also includes Campylobacter sp. (eg. C. jejuni – major cause of food poisoning in UK / US )
• Phylum: Chlamydias


  •Characteristics: •They are typically oval shape •They have a cell wall •They lack eptidoglycan •They are submicroscopic size

  •These microorganisms are gram negative
• Chlamydias


  •They are obligate intracellular parasites •These microbes will grow only inside of a living host cell  •These microbes have a type of unique developmental cycle:
• Chlamydias


  • Two forms of cells
• Elementary body


  • Rigid cell wall
  • Can survive outside of host cell
  • Infective agent
• Reticulate body


  • Fragile cell wall
  • Can't survive outside of host cell
  • Not infective
  • Adaptive for growth
• Intracellular Reticulate Body


  Chlamydias - 71% increase in 2000-2009 {67,173 to 114,686} but forms 30% of all STDs.
• Spirochetes


  Unique tightly-coiled, helical shape with endoflagella inside a flexible sheath - hence has motility characteristic.

  Some free-living but many pathogenic such as Treponema pallidum (syphilis) and Borrelia burgdorferi ( Lyme disease).