Bacterial Growth and Nutrition

Question 1

Macroelements of culture medium are measured in what units?

Answer 1

gm/L

Question 2

What are the Macroelement?

Answer 2

CHONSP

Question 3

What type of organism is Sulfolobus according to Nutritional classification?

Answer 3

Chemoautotroph/Litoautotroph

Carbon source: CO2
Energy source: Inorganic compound/chemicals

Question 4

What type of organism is Rhodobacter according to Nutritional classification?

Answer 4

Photoheterotroph (like Chloroflexus)

Carbon source: Organic compounds
Energy source: Light

Question 5

What type of organism is Sulfurousmaccording to Nutritional classification?

Answer 5

Chemoheterotroph
(Same with fungi and archaea)

Carbon source and Energy source: Organic compounds

Question 6

Which chemical is the most important chemical requirement next to water for skeleton or backbone of all organic molecules

Answer 6

carbon

50% of phospholipids

Question 7

Percentage distribution of Nitrogen in Phospholipids

Answer 7

14%

C>O>N>H

Question 8

Percentage distribution of Hydrogen in Phospholipids

Answer 8

8%

C>O>N>H

Question 9

Percentage distribution of Oxygen in Phospholipids

Answer 9

20%

Question 10

Bacterial classification according to water requirement: REQUIRE NaCl for growth

Answer 10

Halophiles

Question 11

Bacterial classification according to water requirement: Persists in DRY environment

Answer 11

Xerophiles or Xerotolerant

Question 12

Classification of bacteria based on oxygen requirement: presence of catalase and SOD

Answer 12

Obligate Aerobes

Question 13

Classification of bacteria based on oxygen requirement: can grow in air temperature and may use oxygen for energy yielding chemical reactions

Answer 13

Facultative Aerobes

Question 14

Among molds, Mycobacteria, Legionella and N. gonorrhea, which requires presence of CO2?

Answer 14

N. gonorrhea (similar to Mammalian cells)

molds, Mycobacteria, Legionella can grow in standard air atmosphere of 21% oxygen

Question 15

This process of energy production in facultative anaerobes is characterized by substrate phosphorylation in which a pyrophosphate bond is donated directly to ADP by a phosphorylated intermediate

Answer 15

Fermentation

Question 16

Classification of bacteria based on oxygen requirement: organisms that require a substance other than O2 as H-acceptor

Answer 16

Obligate anaerobes

Question 17

Microaerophiles requires small amount of oxygen at range _______% for aerobic respiration

Answer 17

2-10%

Question 18

Classification of bacteria based on oxygen requirement: organisms that cannot withstand 21% oxygen levels (since higher concentrations are inhibitory to them)

Answer 18

microaerophiles

Grows best at 1-15% oxygen levels
ex. campylobacter and helicobacter pylori

Question 19

Classification of bacteria based on oxygen requirement: organisms that grows in the presence of oxygen, but they do not use it as H-acceptor

Answer 19

aerotolerant

Question 20

Which enzyme for Oxygen radicals is present in aerotolerant organisms?
A. None
B. Catalase
C. SOD
D. both catalase and SOD

Answer 20

C. SOD only

lactobacillus are arotolerant

Question 21

Classification of bacteria based on oxygen requirement: organisms that present growth throughout the culture broth tube

Answer 21

Facultative anaerobes

ex. E. coli and Staphylococcus

Question 22

Classification of bacteria based on oxygen requirement: organisms that are indifferent to oxygen

Answer 22

aerotolerant

Question 23

Two major types of equipment used in continuous culture:

Answer 23

Chemostat and Turbidostat

Question 24

Which of the following is not an element of the most common type of continuous culture device?
A. substrate reservoir
B. optical sensor
C. culture vessel
D. spent culture bottle

Answer 24

B. Optical sensing device and Photoelectric device are components of the Turbidostat (biostat); the most common continuous culture device is the chemostat

Question 25

T/F: Bacterial cells will grow at a constant rate in the Chemostat, i.e., the exponential phase, because there will be no nutrient depletion due to continuous nutrient supply into the reservoir

Answer 25

T

Question 26

The growth rate of organisms in chemostat depends upon which two factors?

Answer 26

Dilution rate Limiting nutrient concentration

Question 27

Which of the following is not a component of the Biostat? A. sterile reservoir B. culture vessel C. photocell D. spent culture bottle E. light source

Answer 27

D. is a component of chemostat The rest are of Turbidostat

Question 28

Which equipment used in continuous culture operates best in high dilution rates?

Answer 28

Turbidostat

Question 29

Which equipment used in continuous culture has a constant dilution rate?

Answer 29

Chemostat

Question 30

T/F: Continuous cultures works as a closed cultivation system

Answer 30

F = open

Question 31

The process of maintaining the microbial cells in the log or exponential phase refers to the:

Answer 31

steady-state of growth

Question 32

Biomass concentration can be estimated indirectly through the following except: A. Measuring an important cellular component such as protein B. Preparing a standard curve correlating dry weight with viable cell count C. Determining the volume occupied by cells that have settled out of suspension

Answer 32

B. Preparing a standard curve correlating dry weight with viable cell count that's direct measurement of biomass density

Question 33

What is measured in turbidimetry to indicate bacterial growth?

Answer 33

light absorbance

Question 34

What is the formula for CFU/mL (no. of CFUs/mL in undiluted bacterial suspension)?

Answer 34

plate count x dilution x 10

Question 35

Which of the following is not used in direct cell count? A. Petroff-Hausser counting chamber B. Plating C. Hemocytometer D. Coulter chamber

Answer 35

B. Plating and Serial dilution are indirect count

Question 36

Which phase of the growth curve in batch cultures do enzymes and intermediates form and accumulate until they are present in concentrations that permit growth to resume?

Answer 36

Lag phase

Question 37

Rate of exponential growth of a bacterial culture is expressed as __________, also the doubling time of the bacterial population

Answer 37

generation time Generation time (G) is defined as the time (t) per generation (n= number of generations) (G=t/n)

Question 38

Which phase of the growth curve in batch cultures do the exhaustion of nutrients or the accumulation of toxic products causes growth to cease completely?

Answer 38

Stationary phase (after Lag/Exponential phase)

Question 39

These are metabolites produced after the active stage of growth

Answer 39

secondary metabolites

Question 40

Bacteria typically produce antibiotics in which phase of the growth in cultures?

Answer 40

Stationary phase

Question 41

This pertains to bacterial culture phenomenon which is thought to be the result of a genetic response triggered in starving, stationary phase cells.

Answer 41

Viable But Not Culturable (VBNC)

Question 42

the optimal temperature for many free-living forms

Answer 42

30 deg Celsius