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BIO246 Microbiology (Part 2, 4 lecture Qs (Symbiosis (" detail…

- - - - Gram Positive
        
        cocci
        
        Staphylococcus
        
        cluster forming
        
        MSA
        
        Facultative Anaerobe
        
        non-motile
        
        species?
        
        Streptococcus
        
        chain forming
        
        aerotolernt anaerobe
        
        species
        
        classified by lysis on blood
        
        Endospore forming
        
        Bacillus
        
        Aerobic
        
        facultative anaerobes or obligate anaerobe
        
        Catalase +
        
        species?
        
        Clostridium
        
        Obligate anaerobic bacteria
        
        Catalase -
        
        species
      - Gram Negative
        
        Pseudomonads
        
        motile
        
        Polar Flagella
        
        Oxidative
        
        oxidase +
        
        fermentation -
        
        obligate aerobe or obligate anaerobe (nitrate respiration)
        
        species?
        
        Enteric
        
        Rod
        
        most motile
        
        peritrichous flagella
        
        Non Motile: Klebsiella,shigella,yersinia
        
        -ve oxidase (no cytochrome c)
        
        Facultative Anaerobe
        
        Oxidative & Fermentative
        
        genus?
        
        Species?
  - - - Physical
        
        water availability
        
        factors affecting water availability
        
        high solutes makes water less accessible
        
        type of solutes
        
        absorption of water to solid surface
        
        liquid water is the universal solvent & is 70% of a cell
        
        oxygen
        
        very reactive element
        
        some bacteria are sensitive to it i.e obligate anaerobes
        
        a substantial component of the atmosphere
        
        in aerobic respiration is an electron acceptor
        
        obligate aerobes need oxygen
        
        PH
        
        bacteria do have some regulation over their PH particularly those adapted to specific environments
        
        Kills by
        
        disruption of membranes
        
        inhibiting enzymes
        
        inhibiting transport/uptake systems
        
        altering nutrient availability/toxicity
        
        effects bacteria because they grow in aqueous environments
        
        Temperature
        
        Bacterial have no internal regulation
        
        two forms:dry heat and moist heat
        
        dry heat- complete incineration
        
        less effective than moist
        
        e.g
        
        ovens
        
        2 more items...
        
        flame sterilization
        
        1 more item...
        
        moist heat
        
        more efficient than dry
        
        e.g
        
        boiling
        
        3 more items...
        
        steam
        
        3 more items...
        
        Autoclave
        
        1 more item...
        
        kills by:
        
        coagulation and denaturation of proteins
        
        degradation of nucleic acids
        
        disruption and melting of cell membranes
        
        Radiation
        
        UV Radiation
        
        kills by effecting DNA
        
        misreading of genes
        
        mutations
        
        sterilizes surfaces or atmospheres
        
        BUT does not penetrate glass, plastic, paper or water
        
        Ionising radiation
        
        sterilizes against bacteria and spores BUT doesn't work against viruses
        
        used to sterilize plastics. petri dishes, gloves, syringes
        
        cold sterilization: antibiotics, hormones, US mail
        
        Filtration
        
        physical removal (e.g washing, scrubbing, vacuuming) can be just as effective
        
        used for bacteria and spores BUT not viruses
        
        used to sterilize air and heat sensitive solutions
      - Chemical
        
        chemical agents with bacterial specificity
        
        Alcohols
        
        kills by membrane damage and protein denaturation
        
        Aldehydes
        
        toxic & spore killing. kills by inactivating enzymes
        
        Ethylene oxide gas
        
        effective but explosive
        
        Halogens
        
        oxidizes cell components
        
        Phenolics
        
        denatures proteins and disrupts membranes
        
        heavy metals
        
        inactivates proteins
        
        Detergents
        
        destroys cell membranes & denatures proteins
        
        factors effecting efficiency of chemicals
        
        nature of chemical
        
        population size
        
        contact time
        
        death proportional to time
        
        cell physiology
        
        young cells more sensitive
        
        temperature
        
        higher temp. better
        
        local enviroment
        
        organic matter decreases effectiveness
    - - Autoclaving process
        
        temperature sensitive tape for proof that temperature was reached
        
        spore strips
      - materials
        
        used to sterilize
        
        glassware
        
        media
        
        solutions
        
        equipment
        
        cannot be used for
        
        heat labile materials (e.g plastics that melt)
        
        paper
        
        heat sensitive chemicals (e.g. antibiotics, sugars etc)
      - efficiency is effected by:
        
        hydration
        
        time of exposure
        
        tempreture
        
        PH
        
        lower the PH the more efficient the process
        
        pressure
        
        how it was packed
- - - - Value of bacteria in the human gut
        
        beneficial functions
        
        contribute to carbohydrate and lipid absorption
        
        induce production of capillaries in the villi
        
        induce production of proteins that help with innate immunity
        
        induce development of gut-associated lymphoid tissue
        
        stimulates the production of cross-reactive antibodies
        
        digestion of complex carbohydrates
        
        what happens without bacteria
        
        reduced
        
        mucosal cell turnover
        
        mucosa associated lymphoid tissue
        
        increased
        
        caloric intake to sustain body weight
      - "what value do bacterial symbiotes have for animals?"
        
        nutrient exchange
        
        plant wall and cellulose digestion
        
        synthesizes and excretes vitamins
        
        antagonize other bacteria
        
        prevents colonization by pathogens
        
        stimulate the development of gut mucosal tissues
        
        a reservoir of genomes
      - symbiosis definition
        
        A permanent or stable association between a microbe and at least one other organism. It is a survival strategy that results in evolutionary advantage. In mutual symbiosis this results in a mutual benefit for both partners.
        
        allows for the occupation of novel metabolic and ecological niches
  - - - structures of archea
        
        16S ribosomes
        
        branched & saturated lipid chains has a higher melting point
        
        have different cell components: tRNA, ribosomes,elongation factors & RNA polymerases
        
        cell wall
        
        have pseudomurein rather than peptidoglycan
        
        some have no cell walls, only plasma membrane
        
        contain complex polysaccharides
        
        protein-based cell walls- contain glycoprotein
      - structure of prokaryotes
        
        plasmamembrane
        
        phosholipid bilayer
        
        cell wall
        
        peptidoglycan is a major component
        
        flagellum/flagella
        
        oranelles of locomotion
        
        composed of proteins:flagellin
        
        different flagella shapes
        
        capsule
        
        ribosomes
        
        site od protein synthesis
        
        compsed of RNA and protein
        
        nucleoid
        
        inclusion bodies
      - gram-negative
        
        gram-negative lipid A can be toxic- an exotoxin
  - - - Differential Media
        
        contains additives that cause an observable change in the medium when a particular chemical reaction occurs. useful for differentiating bacteria according to a biochemical characteristic
      - Selective Media
        
        has ingredients added to inhibit the growth of one group of organisms over another
      - Media uses for bacterial isolation
        
        colonies on selected media can then be grown on new sterile media to achieve pure colonies
        
        often used in conjunction
        
        used to help isolate colonies in a mixed culture by characterizing defining features
      - methods of bacterial identification
        
        morphology
        
        metabolism
  - - - transformation
        
        the bacteria uptakes a fragment of DNA from another lysed bacterial cell that is in the environment and integrates it into its own genome
        
        the process is random so the result can be either stable (and thus successful) or it degrades and thus results in a unsuccessful transformation
        
        cells that can take up the DNA are called "competent cells"
        
        must be in a particular physiological state for success
        
        a short period in the growth cycle (the exponential phase)
        
        competent cells synthesize competence-specific proteins
        
        can be used in recombinant DNA process
        
        cells can be treated with CaCl2 to make them act as competent cells by making the membrane permeable
      - generalised transduction
        
        transfer pf host DNA by a phage (bacterial virus) to another bacteria
      - conjugation
        
        the transfer of a plasmid by direct cell to cell contact between in which the donor cell (the one that contains the plasmid) replicates it plasmid and transfers it to the recipient cell
        
        plasmid is transferred via a "mating bridge" formed from pili
        
        a one way transfer
        
        why not all cells have plasmids
        
        plasmid could have been lost (common occurence in stationary phase)
        
        plasmid wasn't equally distributed during cell division
        
        there is a slight growth advantage to cells without a plasmid since thely don't have to use energy to replicate the plasmid
        
        mechanism is used in High frequency recombination
  - - - Beneficial Relationships
        
        ectomycorrhizal:outside the roots
        
        high degree of host specificity
        
        Ericaceae fungi
        
        basidiomycets and ascomycetes
        
        erocaceae grow on infertile acidic soil
        
        increases biomass
        
        enhances nitrogen uptake
        
        orchid fungi
        
        supply carbon to seedlings
        
        unclear of benefits for fungus- suggested - supply of ammino acids and vitamins
        
        formed by basidiomycetes and sometimes a ascomycete
        
        penetrates outermost root cortex but never invades the plant's cells
        
        penetrates further in the roots of gymnosperms (ferns etc.) than angiosperms
        
        general relationship- mutual symbiosis
        
        plant supplies fungus with a carbon source in the form of sugars
        
        the fungus will die without the sugars
        
        fungus transports nutrients from soil to plant
        
        plant growth is stunted without fungal supplement
        
        for instance P & N
        
        good in nutrient poor soils
        
        mechanisms
        
        increase physical access
        
        2 more items...
        
        in some relationships it may transport C between plants
        
        fungi can form networks between plants. the fungal mats can extend a few cm to a few m
        
        plays a key role in nutrient cycling
        
        the N & P cycles particularly
        
        reduce the uptake of toxic metals, alter competitive interactions by increasing genotypic variation, increase pathogen resistance increase drought tolerance (which is important for plants under environmental stress e.g fluctuating water table),
        
        Endomycorrhizal
        
        formed by glomeromycete fungi
        
        not host specific
        
        penetrates the root cortex- inside the root but does not alter its morphology
        
        arbuscular mycorrhizal fungi
        
        all are obligate biotrophs
        
        inside the root has intracellular and intercellular hyphae as well as a network of hyphae that extend outside the root
        
        intracellular hyphae
        
        intracellular arbuscules have vesicles
        
        1 more item...
        
        intracellular hyphae are arbuscules which are analogous to haustroria (fungal pathogens). tree-branch like structures
        
        intercellular mycellium
        
        outside the root
        
        form extensive networks of hyphae. in some cases connects differnet plants
        
        fossils of spores indicates the relationship may be as old as the first land plants
        
        maintains soils structure
      - Harmful Relationships
        
        can be pathogens
        
        e.g chestnut blight, dutch elm disease and ergot of rye
        
        parasitic
        
        out-compete plants