Exercise 4 Quantitative Bacteriology Flashcards
It is an orderly increase in the quantity of cellular constituents
growth
growth is an orderly increase of what?
quantity of cellular constituents
The growth of bacteria depends upon the ability of the cell to form ______ ______ from the nutrients available in the environment
new protoplasm
this activity of bacteria depends on the ability of the cell wall to form new protoplasm from nutrients available in the environment
growth
In most bacteria, growth involves what processes? (6) basically its life cycle
- increase in cell mass and number of chromosomes 2. duplication of the bacterial chromosomes 3. synthesis of new cell wall and plasma membrane 4. partitioning of the two chromosomes 5. septum formation 6. division of the cell into 2 daughter cells
this type of reproduction of bacteria where there is an increase in cell mass and number of chromosomes, duplication of the bacterial chromosomes, synthesis of new cell wall and plasma membrane, partitioning of the two chromosomes, septum formation, division of the cell into 2 daughter cells
binary fission
two daughter cells contain what components?
copy of the genome and other vital components
after its division, these cells will contain a copy of the genome and other vital components from its parent cell
daughter cells
the parameters used for unicellular organisms when measuring growth
changes in cell mass changes in cell numbers
changes in cell mass and cell numbers are parameters used to measure the growth of what organisms?
unicellular organisms (e.g bacteria)
methods that can be employed to determine cell numbers
Direct or indirect methods
Direct or indirect methods are employed to determine ___ ___ of cultures
cell numbers
2 methods that the growth in a population is usually measured quantitatively by
plate count and turbidimetric methods
plate count and turbidimetric methods are used to quantitatively measure what?
growth in a population
plate count is also known as
viable count
viable count is also known as
plate count
it is usually done by diluting the original sample, plating aliquots of the dilution into an appropriate culture medium and then incubating the plates under proper conditions to form colonies, after incubation, colonies are counted
viable cell count
provide the sequence for viable cell count
- Diluting the original sample 2. Plating aliquots of the dilutions into an appropriate culture medium 3. incubation of plates under proper conditions 4. counting of colonies
The ideal source of colony in determination of the total number of viable cells
one cell
Colony from one cell is used for accurate determination of the total number of ____ ____
viable cells
due to the possibility of not being certain that each colony will arise from an individual cell, the results in viable counts are often expressed in terms of ____ ____ ____ rather than the number of microorganisms
colony forming units(CFU)
in viable counts, colony forming units (CFU) are expressed rather than ____ __ _____ due to the possibility of not being certain that each colony will arise from an individual cell
number of microorganisms
colony forming units (CFU) rather than number of microorganisms are expressed in viable counts because?
there is a possibility of not being certain that each colony will arise from an individual cell
this employs a spectrophotometer to measure the turbidity of a suitable liquid medium inoculated with a specified microorganism at a known physiological state of growth
turbidimetric method
a device used to measure turbidity of a suitable liquid medium inoculated with microorganism
spectrophotometer
what does turbidimetric method measures?
turbidity of the liquid medium inoculated with microorganism
a function of microbial cell growth
turbidity
turbidity is a function of microbial ____ ____
cell growth
turbidimetric method is based on the close relationship of what 2 variables?
observable turbidity changes in microbial cell numbers
establishes the relationship between OD readings and viable counts
standard optical density curve
standard optical density curve establishes the relationship between
OD readings and viable counts
What is plotted in the standard optical density curve
turbidity of different concentrations of a given species of microorganisms vs number of viable microorganism per ml of sample tested determined by plate count methods
turbidity of different concentrations of a given species of microorganisms vs number of viable microorganism per ml of sample tested determined by plate count methods is plotted to generate what curve?
standard optical density curve
this is used for visual estimation of any given suspension of microorganism
turbidimetric standard calibration standard curve
turbidimetric calibration standard curve is used for?
visual estimation of any given suspension of microorganism
What specimen were used in this activity?
E coli
how old was the E coli during the exercise proper?
24-h old
what media was utilized for this exercise?
Plate count agar (PCA)
alternative media that can be utilized in performing this exercise
standard methods agar
serial diluents utilized for this exercise
Distilled water phosphate buffer Peptone water with saline solution
concentration of saline solution for the peptone water with saline solution
0.0085
concentration of peptone water for the peptone water with saline solution
0.001
diluent used as stock suspension of E coli
phosphate buffer
final volume of the stock suspension utilized in this exercise
15 ml
volume of aliquot transferred to plate
0.1 ml
which dilution was plated in duplicates in this exercise
10^-6 and 10^-7 dilutions
tool utilized in spreading the aliquot in the plate
L-shaped glass rod
incubation period for the plates inoculated with the aliquots
24-48h
valid counts for bacteria
25-250 colonies
if only one of the dilutions gives valid count what formula is used?
with photo attached
if two consecutive dilutions gives valid count what formula is used?
with photo attached
computing for the number of cells per ml at each particular dilution formula
with photo attached
is the reciprocal of the final dilution
dilution factor
dilution factor is the _____ of the final dilution
reciprocal
product of all dilutions used
final dilution
final dilution is the ____ of all dilutions used
product
N1 in the formula for two consecutive dilutions is the
number of plates in lower dilution counted
N2 in the formula for two consecutive dilutions is the
number of plates in the next higher dilution counted
d in the formula for two consecutive dilutions is the
lower dilution
the absorbance where OD was read
590nm
dilution formula
with photo attached
characteristics of good diluen
non toxic readily available easy to prepare free from contaminants stable etc
valid values for OD readings to be reported in standard curve
0.1 - 0.5 values
the x axis of standard curve
OD readings
the y axis of standard curve
number of cells/ml
final volume of the diluent utilized in this exercise in the estimation of the cell number by OD determination
5ml
volume transferred from the stock E coli stock suspension to each of the serial diluents to achieve 10^-2 dilution (final vol of the dram vial 50 mL)
0.5 ml
volume transferred from the serial diluent to the 1st screw cap with the dilution of 10^-4 (final vol of the tube 10 mL)
0.1 ml
with the absence of vortex mixer, what needs to be done to properly distribute the culture in the serial diluents?
properly shake the tube
