Exercise 4 Quantitative Bacteriology

Question 1

It is an orderly increase in the quantity of cellular constituents

Answer 1

growth

Question 2

growth is an orderly increase of what?

Answer 2

quantity of cellular constituents

Question 3

The growth of bacteria depends upon the ability of the cell to form ______ ______ from the nutrients available in the environment

Answer 3

new protoplasm

Question 4

this activity of bacteria depends on the ability of the cell wall to form new protoplasm from nutrients available in the environment

Answer 4

growth

Question 5

In most bacteria, growth involves what processes? (6) basically its life cycle

Answer 5

1. 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

Question 6

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

Answer 6

binary fission

Question 7

two daughter cells contain what components?

Answer 7

copy of the genome and other vital components

Question 8

after its division, these cells will contain a copy of the genome and other vital components from its parent cell

Answer 8

daughter cells

Question 9

the parameters used for unicellular organisms when measuring growth

Answer 9

changes in cell mass changes in cell numbers

Question 10

changes in cell mass and cell numbers are parameters used to measure the growth of what organisms?

Answer 10

unicellular organisms (e.g bacteria)

Question 11

methods that can be employed to determine cell numbers

Answer 11

Direct or indirect methods

Question 12

Direct or indirect methods are employed to determine ___ ___ of cultures

Answer 12

cell numbers

Question 13

2 methods that the growth in a population is usually measured quantitatively by

Answer 13

plate count and turbidimetric methods

Question 14

plate count and turbidimetric methods are used to quantitatively measure what?

Answer 14

growth in a population

Question 15

plate count is also known as

Answer 15

viable count

Question 16

viable count is also known as

Answer 16

plate count

Question 17

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

Answer 17

viable cell count

Question 18

provide the sequence for viable cell count

Answer 18

1. 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

Question 19

The ideal source of colony in determination of the total number of viable cells

Answer 19

one cell

Question 20

Colony from one cell is used for accurate determination of the total number of ____ ____

Answer 20

viable cells

Question 21

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

Answer 21

colony forming units(CFU)

Question 22

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

Answer 22

number of microorganisms

Question 23

colony forming units (CFU) rather than number of microorganisms are expressed in viable counts because?

Answer 23

there is a possibility of not being certain that each colony will arise from an individual cell

Question 24

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

Answer 24

turbidimetric method

Question 25

a device used to measure turbidity of a suitable liquid medium inoculated with microorganism

Answer 25

spectrophotometer

Question 26

what does turbidimetric method measures?

Answer 26

turbidity of the liquid medium inoculated with microorganism

Question 27

a function of microbial cell growth

Answer 27

turbidity

Question 28

turbidity is a function of microbial ____ ____

Answer 28

cell growth

Question 29

turbidimetric method is based on the close relationship of what 2 variables?

Answer 29

observable turbidity changes in microbial cell numbers

Question 30

establishes the relationship between OD readings and viable counts

Answer 30

standard optical density curve

Question 31

standard optical density curve establishes the relationship between

Answer 31

OD readings and viable counts

Question 32

What is plotted in the standard optical density curve

Answer 32

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

Question 33

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?

Answer 33

standard optical density curve

Question 34

this is used for visual estimation of any given suspension of microorganism

Answer 34

turbidimetric standard calibration standard curve

Question 35

turbidimetric calibration standard curve is used for?

Answer 35

visual estimation of any given suspension of microorganism

Question 36

What specimen were used in this activity?

Answer 36

E coli

Question 37

how old was the E coli during the exercise proper?

Answer 37

24-h old

Question 38

what media was utilized for this exercise?

Answer 38

Plate count agar (PCA)

Question 39

alternative media that can be utilized in performing this exercise

Answer 39

standard methods agar

Question 40

serial diluents utilized for this exercise

Answer 40

Distilled water phosphate buffer Peptone water with saline solution

Question 41

concentration of saline solution for the peptone water with saline solution

Answer 41

0.0085

Question 42

concentration of peptone water for the peptone water with saline solution

Answer 42

0.001

Question 43

diluent used as stock suspension of E coli

Answer 43

phosphate buffer

Question 44

final volume of the stock suspension utilized in this exercise

Answer 44

15 ml

Question 45

volume of aliquot transferred to plate

Answer 45

0.1 ml

Question 46

which dilution was plated in duplicates in this exercise

Answer 46

10^-6 and 10^-7 dilutions

Question 47

tool utilized in spreading the aliquot in the plate

Answer 47

L-shaped glass rod

Question 48

incubation period for the plates inoculated with the aliquots

Answer 48

24-48h

Question 49

valid counts for bacteria

Answer 49

25-250 colonies

Question 50

if only one of the dilutions gives valid count what formula is used?

Answer 50

with photo attached

Question 51

if two consecutive dilutions gives valid count what formula is used?

Answer 51

with photo attached

Question 52

computing for the number of cells per ml at each particular dilution formula

Answer 52

with photo attached

Question 53

is the reciprocal of the final dilution

Answer 53

dilution factor

Question 54

dilution factor is the _____ of the final dilution

Answer 54

reciprocal

Question 55

product of all dilutions used

Answer 55

final dilution

Question 56

final dilution is the ____ of all dilutions used

Answer 56

product

Question 57

N1 in the formula for two consecutive dilutions is the

Answer 57

number of plates in lower dilution counted

Question 58

N2 in the formula for two consecutive dilutions is the

Answer 58

number of plates in the next higher dilution counted

Question 59

d in the formula for two consecutive dilutions is the

Answer 59

lower dilution

Question 60

the absorbance where OD was read

Answer 60

590nm

Question 61

dilution formula

Answer 61

with photo attached

Question 62

characteristics of good diluen

Answer 62

non toxic readily available easy to prepare free from contaminants stable etc

Question 63

valid values for OD readings to be reported in standard curve

Answer 63

0.1 - 0.5 values

Question 64

the x axis of standard curve

Answer 64

OD readings

Question 65

the y axis of standard curve

Answer 65

number of cells/ml

Question 66

final volume of the diluent utilized in this exercise in the estimation of the cell number by OD determination

Answer 66

5ml

Question 67

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)

Answer 67

0.5 ml

Question 68

volume transferred from the serial diluent to the 1st screw cap with the dilution of 10^-4 (final vol of the tube 10 mL)

Answer 68

0.1 ml

Question 69

with the absence of vortex mixer, what needs to be done to properly distribute the culture in the serial diluents?

Answer 69

properly shake the tube