G: Environmental Factors Influencing Growth Flashcards
What does -phile mean
means prefer and often means requires
What does -tolerant mean
will grow in a wider range of conditions than non-tolerant
What does -facultative mean
optional mode
What does -obligate mean
an absolute requirement
What does -hyper mean
above/greater than
What does -extreme mean
outside of normal range
How is water activity expressed as, and what does it reflect
aw, reflects how wet/dry an environment is and concentration of solutes dissolve in the water
Equation for aw
aw= Psoln/Pwater where =vapour pressure
Give the range of aw. What does this mean
0 to 1. The higher the [soulte] the lower the water activity. Water has an aw of 1
How does bacterial cells in an environment with high aw protect themselves
by their peptidoglycan
When will bacterial cells undergo plasmolysis
in an environment with low aw (<0.9)
What is the typical aw minimum for bacteria
0.95-0.98
What are osmotolerant bacteria called if solute is NaCl
halotolerant
give an example of halotolerant bacteria and aw limit
Staphyloccocus spp. lower limit is 0.85
What are halophiles
adapted to grow in presence of salts like NaCl, require high levels to grow