Microbial Taxonomy

Microbial Taxonomy

1. Taxonomy includes

   • Identification
   • Classification
   • Nomenclature

2. Relations Identification

   • Evolutionary Evidence
     • Not reliable, as an organism can evolve into multiple dissimilar organisms
   • Similarity of observable characteristics
     • Phenetic Classification
   • Phylogenetics
     • Genetic Similarity and evolutionary relatedness
     • Evolution occurs via DNA mutation accumlation. The greater number of differences between 2 DNA molecules, the longer since they have had an ancestor
     • An organisms genome can be used to track the difference between and within species
       • Between Species, 16s (18s) rRNA gene sequencing is used
         • Prokaryotescontain the 16s, Eukaryotes contain 18s both as sub-units to create the ribosomes
         • Has intra-strand sequence complementarity
         • Has regions of similarity and variability
           • Can be used to determine relatedness
             • Woese and Wolfe used the sequence as "molecular clocks" to classify micro-organisms on their relatedness
               • Identified a third domain of life, Archaea
                 • Each domain can be broken down into Kingdoms etc
                   • K P C O F G S
         • Change slowly
       • Protein coding genes can be used within species
         • Change quickly
         • Allows Phylogenetic Trees to be created

3. Naming

   • Binomial nomenclature
     • Each distinct organism has 2 names
       • First is generic. It is the Genus
         • Starts with Capital letter
         • Can be abbreviated
       • Second is specific, is the species name
         • Always has lower-case
         • Cannot be abbreviated
     • When written are underlined and when typed, italicised

4. 3 Main Domains

   • Domain Eukarya
     • Algae
       • Coloured tides due to algal blooms
       • Can cause problems from toxins or accumulated biomass
     • Fungi
       • Include multicelluar and single celled
       • Sacchromyces cerevisiae
         • Wine Yeast
       • Aspergillus niger
         • Black Mould of food. Can produce toxins
     • Protozoa-1
       • Giardia lamblia
         • Cysts are ingested, converts into a trophozoites and then passed in the faeces
         • Causes Giardiasis, traveller's diarrhoea
     • Protozoa-2
       • Genus Trypanosoma
         • Parasitic and cause major diseases
         • Causes African Sleeping Sickness
       • Genus Leishmania
         • Are Trypanosomes
         • Cause a very significant range of diseases called Leishmaniases
     • Helminths
       • Types of Worms
         • Round worm and Flatworm
       • Cause Schistosomiasis
   • Domain Archaea
     • Distinct Ribosomes
     • Variation in RNA Polymerase
     • No peptidoglycan in cell walls
     • Live in extreme conditions
       • 3 Groups
         • Halophiles
           • Live in extremely salinity
         • Methanogens
           • Live in anaerobic conditions and produce methane
         • Thermophiles
           • Grow at high temperatures
   • Domain Bacteria
     • Can be called Eubacteria
     • Streptomyces
       • Gram Positive
     • Proteobacteria
       • Large group that are Gram Negative bacteria
       • Wide range of energy generating mechanisms
         • Photoautotrophs
           • Energy from light
         • Methanotrophs
           • Energy from Methane
         • Chemolithotrophs
           • Energy from inorganic reduced compounds
         • Chemoorganotrophs
           • Energy through Oxidation of electron donors