Chapter 6
What are the physical and chemical growth requirements for Microbes?
Physical: pH temperature and osmotic pressure
Chemical: CHONPS (macronutrients), growth factors, trace elements, and oxygen
What are the three steps of the nitrogen cycle?
Fixation, Nitrification, and Denitrification
What is the difference between antisepsis and sterilization?
Antisepsis is for living tissue
Sterilization is the complete removal of all living microbes
How do prokaryotes transfer genes?
Vertical and horizontal gene transfer
If this nutrient were absent from a bacterial growth medium; then NO growth would occur if this medium were inoculated.
A: Phosphorous
B: Sulfur
C: Carbon
D: Nitrogen
E: If any of the above nutrients were missing from the growth medium, no growth would occur.
E: If any of the above nutrients were missing from the growth medium, no growth would occur.
What protective enzyme neutralizes the effect of O2 radicals as a protection from Oxygen Byproducts?
SOD: Superoxide Dismutase. It is found in aerobes, aerotolerant anaerobes, and facultative anaerobes
What acts as the catalyst for N2 fixation? Does the catalyst function aerobically or anaerobically?
Nitrogenase (only acts anaerobically and requires tremendous energy)
Describe the steps in the Use-Dilution Test
Metal rings are dipped in test bacteria are dried up
Dried cultures are placed in disinfectant for 10 minutes at 20 degrees celsius
Rings are transferred to culture media to determine if bacteria survived or not
What is tRNA’s role in protein synthesis and how does it know what to do?
tRNA's role in protein synthesis is to translate transcript in order to make the correct sequence of amino acids. tRNA knows what to do because of the instructions it receives from mRNA
Which statement among A-C is not applicable to flocculation, or floc formation, during wastewater treatment?
A: Filamentous bacteria enhance floc formation.
B: Flocculation is important for the production of a clear effluent stream of wastewater.
C: Flocculation increases the amount of BOD entering effluent stream of wastewater.
D: A-C are all applicable.
C: Flocculation increases the amount of BOD entering effluent stream of wastewater.
Define Biofilms. What is a key factor in biofilm formation and what parts of the bacteria are used?
Biofilms are created from many bacterial species that form surface attached communities using an EPS. Adherence is a key factor in biofilm formation and they use their fimbriae/pili
Define BOD. Which of these represent a low BOD?
BOD means biochemical oxygen demand, and it is the amount of O2 removed from the environment respiration.
Describe all ways of pasteurization
Low temp/long time (LTLT): 63 degrees celsius/30 minutes
High temp/short time (HTST): 72 degrees celsius/15 seconds
Ultra-high temperature (UHT): 134 degrees celcius/1-2 seconds
What did the Griffith experiment reveal
It revealed that DNA from dead encapsulated bacteria can transform living un-encapsulated bacteria into living encapsulated bacteria.
Which among A - D is FALSE?
A: Denitrification = anaerobic respiration
B: Nitrification = lithotrophy
C:Ammonification and N2-fixation: yield ammonium (NH4+)
D: N2O greenhouse gas: comes from denitrification
E: None are false; A-D are all true.
E: None are false; A-D are all true.
Describe an obligate anaerobe microbe.
Does not use O2, anaerobically ferments and respires, O2 is toxic, and the growth in the test tube settles to the bottom.
Describe the Wastewater treatment process. What is Activated sludge?
1. Preliminary treatment is what removed solid debris,
2. Primary treatment, fine screens and uses sedimentation tanks remove insoluble particles,
3. Secondary treatment involves microbial decomposition of organic content,
4. Tertiary (advanced) treatment involves chlorination or other chemical applications to eliminate pathogens.
Activated sludge is a process for treating waste water using air and a biological floc composed bacteria and protozoa.
What would happen to a cell going through bactericidal antimicrobial treatment and how will it affect growth and viable cell count?
Bactericidal cell treatment causes the total count of cells to remain the same because they are killed but not lysed, meaning their growth does stop and the cells remaining stay at a constant number once the treatment is in effect. However, the number of viable cells will decrease.
What would happen to a DNA strand if a frameshift mutation occurred and how would that impact the creation of an amino acid?
A frameshift mutation would cause the addition or deletion of a base causing the whole genetic sequence to change. This identity change would cause the creation of the wrong amino acid and would change the protein
Which of the following among A-C is false regarding an Hfr strain?
A: In an Hfr x F- mating, the F- cell is typically always converted to an F+ cell.
B: During conjugation, an F- recipient cell can receive part of the chromosome from an Hfr donor.
C: Hfr strains possess an F factor integrated into their chromosome.
D: None are false; A-C are all true statements.
In an Hfr x F- mating, the F- cell is typically always converted to an F+ cell.
What are the stages of Bacterial Growth in Batch culture? What factors influence the first phase?
Lag, log, stationary and death. The lag phase is affected by inoculum age and size, media composition and physical factors.
What is the process of nitrification? Include the process of lithotrophy and the roles that Nitrosomonas and Nitrobacter play.
Nitrification is the process where NH4+ --> NO2-—> NO3-.
Lithotrophy is the oxidation of ammonium that provides electrons of energy
Nitrosomonas oxidizes NH4+ --> NO2-
Nitrobacter oxidizes NO2- —> NO3-.
What is the difference between ionizing and nonionizing radiation? Which of the two can penetrate cells?
Ionizing radiation has a wavelength <0.1 nm
Nonionizing radiation has a wavelength of 200-300 nm.
Ionizing radiation penetrates cells
Describe the process of conjugation between a Hfr cell x F- cell and what happens with the F- cell after conjugation is complete?
Hfr cell replicates and transfers chromosome copy; initiated within integrated F factor. F- cell recombines with transferred F factor. Since the Hfr cell doesn't contain a complete F factor the F- cell stays as a Recombinant F- Cell.
Which of the following statements is true?
A: In terms of killing effect and penetration, non-ionizing radiation is generally more effective than ionizing radiation.
B: An antimicrobial agent exhibiting bactericidal activity would always show a decrease in viable count.
C: Implementing cold temperatures for food preservation has a bacteriocidal effect rather than a bacteriostatic effect.
D: Disinfection is always a process that yields sterilization.
E: The decimal reduction time is the time for a population to be reduced by 50% following application of an antimicrobial agent or physical condition.
F: none of the above are true.
B: An antimicrobial agent exhibiting bactericidal activity would always show a decrease in viable count.