CH 7 Flashcards
How is microbial growth measured in:
- multicellular organisms
- unicellular organisms
- size and mass
- number and mass
WHAT temperature classification are the ff:
- Humans
- Food
- mesophile
- psycrophile
Where are psychrotrophs located?
and what environment do they thrive in?
Middle of psychrophile and mesophile
prefer cold but can withstand hot
WATER ACTIVITY - ORGANISMS (7)
1.000 Pure Water - ____ & ____
___ Human Blood - Streptococcus, Escherichia
0.980 _______ - ______
_______ Bread - Gram Positive Rods
0.800 Fruit Cake - ______
______ Salted Fish - _____ & _____
0.700 Candy, Dried Fruit - +_____
- Spirillum, Caulobacter
- 0.995
- Seawater - Pseudomonas, Vibrio
- 0.950
- Penicillum
- 0.750 - Halobacterium, Halococcus
- Xeromyces bisporus
PH - ORGANISMS (5)
7
5
3
1
9
7 - Escherichia coli
5 - Rhodophila globiformis
3 - Acidithiobacillus ferrooxidans
1 - Picrophilus oshimae
9 - Bacillus firmus
PHASES OF BACTERIAL GROWTH
adaption phase that occurs upon initial transfer
Lag Phase
PHASES OF BACTERIAL GROWTH
no immediate increase in cell mass/number
Lag Phase
PHASES OF BACTERIAL GROWTH
synthesis of protoplasm
Lag Phase
PHASES OF BACTERIAL GROWTH
cells are dividing at a constant rate
Exponential Phase
PHASES OF BACTERIAL GROWTH
growth rate is at its maximum
Exponential Phase
PHASES OF BACTERIAL GROWTH
cells are mostly uniform
Exponential Phase
PHASES OF BACTERIAL GROWTH
growth rate decreases due to exhaustion of nutrients and accumulation of waste products
Stationary Phase
PHASES OF BACTERIAL GROWTH
stable population size
Stationary Phase
PHASES OF BACTERIAL GROWTH
decline in cells
Death Phase
Reproduction of:
- Multicellular microbes
- Unicellular microbes
- Spores
- Binary Fission
What replicates before binary fission
plasmid
FORMULA
no. of generations
n = (log N2 - log N1) / 0.301
N2 = # of cells at final time
N1 = # of cells at initial time
FORMULA
growth rate
µ = n/t
FORMULA
generation time
g = 1/µ or t/n
3 measurements of growth
Standard Plate Count
Direct Count (Breed Count)
Turbidimetric Method
3 types of standard plate count
serial dilution
pour plate
spread plate
Valid ranges of Mold and Bacteria
Mold: 10-150 colonies/plate
Bacteria: 25-250 colonies/plate
CFU/ml formula
[(ave number of colonies)(df)]/
volume plated
Direct Count formula
bacteria/ml =
[(ave number of microorganisms)(# mcscpc fields in 1cm^2) (DF)] / VOLUME SAMPLE
mcscpc fields in 1cm^2 = 1/area of field of vision
area of OIO
1.77 x 10^-4 cm2
TYPE OF GROWTH MEASUREMENT
most frequently used method
standard plate count
TYPE OF GROWTH MEASUREMENT
reported as colony forming unit
standard plate count
TYPE OF GROWTH MEASUREMENT
can determine # of living cells
standard plate count
TYPE OF GROWTH MEASUREMENT
underestimation of cell population
standard plate count
TYPE OF GROWTH MEASUREMENT
heat sensitive microorganisms cant form colonies
standard plate count (pour plate)
TYPE OF GROWTH MEASUREMENT
both viable and non-viable cells are counted
direct (breed) count
TYPE OF GROWTH MEASUREMENT
overestimation
direct (breed) count
TYPE OF GROWTH MEASUREMENT
uses Petroff-Hausser counting chamber microscope
direct (breed) count
What 2 microorganisms use DIRECT COUNT
cocci and S. agalactia
TYPE OF GROWTH MEASUREMENT
indirectly measures cell mass through turbidity
turbidimetric method
TYPE OF GROWTH MEASUREMENT
a spectrophotometer
turbidimetric method
