Control of Microbial Growth Flashcards
What are Extremophiles?
Organisms that normally live at extremes in environmental conditions
When are Low Temperatures used to Influence rates of chemical reactions?
To preserve foods and cultures. Must add cryoprotectant to prevent ice crystals from disrupting membranes.
When are High Temperatures used to Influence rates of chemical reactions?
To denature proteins and sterlize
Psychrophiles
less than 15 degrees C
Mesophiles
Between 15-45 C
Thermophiles
Greater than 45 C
Hyperthermophiles
Greater than 80 C
Acidophiles
Acidic Ph. less than 6
Alkiliphiles
Basic pH, above 9
Do all microbes require liquid water for growth and reproduction?
Yes
Osmotic Shock
When low solute concentrations outside cells cause water to diffuse in and the cells burst
Osmophiles
Organisms able to live in high concentrations of sugar
Halophiles
Organisms able to live in high concentrations of salt
Barophiles
Organisms able to grow at high hydrostatic pressures
What does Ionizing from Gamma or X Rays do to cells?
Induces formation of radical ions in cell which disrupt cell or polymerize molecules
What do UV rays do to cells?
Forms pyrimidine dimers in DNA
What do Visible spectrum wavelengths to do cells?
Photoautotrophs require different wavelengths. Non-photosynthetic pigments produced by some microbes prevent the formation of oxygen radicals
What do Infrared rays to do cells?
Killing action caused by heat generation
What are 5 requirements for cell growth?
Inorganic nutrients, carbon source, energy source, electron donor, electron acceptor