Exercises 12-13 Flashcards
A form of sexual reproduction in which one develops from an existing organism as an outgrowth
Budding
Long filamentous branches found in actinobacteria and fungi which is important for growth
Hyphae
A fungus that is single celled, eukaryotic, reproduce aexually, and capable of fermentation
Yeast
Why do yeast have to be cultured for longer periods than most bacteria?
Yeasts divides by budding which takes longer time than most bacteria through binary fission
Yeast is eukaryotic. Bacteria is prokaryotic.
Vegetative vs Aerial Mycelia
Vegetative mycelia are non-reproducing while aerial mycelia are reproducing
Stain cells and gives dark blue color to the fungal structure
Cotton Blue
Acts as disinfectants
Phenol
Preserves the fungal structure and clears the tissue
Lactic acid
Can bacteriological media be used for the cultivation of molds?
Yes
Factors affecting bacterial growth
Temperature Nutrients Moisture Aeration pH
Transport processes so slow that growth cannot occur
Mebrane Gelling
Minimum Temperature
Collapse of the cytoplasmic membrane
Thermal lysis
Protein denaturation
Maximum temperature
Enzymatic reactions occuring at maximal possible rate
Optimum
Organisms based on temperature
Psychrophile
Mesophile
Thermophile
Hyperthermophile
Optimum temperature for most strains of E. coli
Near 39C
Maximum temperature for most strains of E. coli
48C
Minimum temperature for most strains of E. coli
8C
Have greater polar and lesser hydrophobic amino acid
Psychrophiles
Other cold adaptation mechanisms
Cold Shock proteins
Cryoprotectants
Maintain cold-sensitive proteins to function in low temperature
Cold shock proteins
Antifreeze proteins or solute
Help prevent the formation of ice crystals that can puncture the cytoplasmic membrane
Cryoprotectants
Example of a cryoprotectant
Glycerol
Heat-stable protein
Thermophiles
Neutral pH
pH 7
pH and temperature relationship
pH decreases as temperature increases
Adverse pH affects at least two aspects of a respiring microbial cell:
Functions of its enzymes
Transport of nutrients
Impermeable to H+ and OH- ions
Cytoplasmic membrane
Impermeable to organic acids
Neutral or alkaline pH
Permeable to organic acids
Acid pH values
Cells must either keep H+ from entering or expel H+ ions as rapidly as they enter
Acid environment
The ratio of the vapor pressure of the air in equilibrium with a substance to the vapor pressure of pure water
Water Activity (aw)
No free water
0 water activity
Pure Water
1 water activity
Which requires high water activity? Bacteria or Fungi?
Bacteria
Which requires higher water activity? Gram positive or negative?
Gram negative
Microorganism able to grow in very dry environments
Xerophiles
Microorganisms able to grow in high sugar concentration
Osmophiles
Microorganisms able to grow in high salt concentration
Halophiles
Cytoplasm has higher solute conc. than the environment
Normal cell
Water diffuses from high to low water concentration
Osmosis
Do not inhibit biochemical processes in the cell
Compatible solutes
No net movement of water occurs
Isotonic solution
Water moves into the cell
Hypotonic solution
Water moves out of the cell
Hypertonic solution
Strong oxidizing agents
Superoxide anion and OH
Microbes that grow better at high CO2 concentrations
Capnophiles
