p.27
Environmental Factors Affecting Microbial Growth
What do microbes do in hypertonic solutions to adapt?
They increase internal solute concentration with compatible solutes to raise their internal osmotic concentration.
p.47
Biofilm Formation and Communication
What is a mature biofilm?
A complex, dynamic community of microorganisms.
p.14
Nutrient Availability and Growth Limitations
What can limit growth during the log phase?
Nutrient concentrations may be limiting.
p.47
Biofilm Formation and Communication
What does heterogeneity in biofilms refer to?
Differences in metabolic activity and locations of microbes.
p.27
Environmental Factors Affecting Microbial Growth
What are compatible solutes?
Solutes that are compatible with metabolism and growth, used by microbes to adapt in hypertonic solutions.
p.8
Binary Fission Process
What is septation in the context of cytokinesis?
Formation of cross walls between daughter cells.
p.19
Reproductive Strategies of Microbes
What is the challenge in determining cell viability in microbiology?
Cells can exist in a variety of states between 'fully viable' and 'actually dead'.
p.45
Biofilm Formation and Communication
What is the primary growth form of most microbes?
Attached to surfaces (sessile) rather than free-floating (planktonic).
What is growth rate in microbial terms?
The rate at which a microbial population increases in number.
p.7
Chromosome Replication and Partitioning
What is the replisome?
The protein complex that unwinds and copies DNA at the forks.
p.14
Nutrient Availability and Growth Limitations
What occurs when there is an abundance of nutrients during the log phase?
Transport mechanisms can become saturated, leading to minimal growth increase despite adding more nutrients.
p.20
Reproductive Strategies of Microbes
What is the purpose of using dilution series in microbial counting?
To obtain accurate counts of microorganisms.
What is the typical method for measuring growth rate?
By plotting the number of cells over time on a growth curve.
p.2
Reproductive Strategies of Microbes
What reproductive strategies do eukaryotic microbes use?
Asexual and sexual reproduction, with haploid or diploid forms.
What does VBNC stand for?
Viable But Non Culturable.
How is the generation time calculated?
By dividing the time interval by the number of generations that occurred.
p.33
Environmental Factors Affecting Microbial Growth
How is the membrane of thermophiles stabilized?
By having more saturated, branched, and higher molecular weight lipids, as well as ether linkages in archaeal membranes.
p.18
Reproductive Strategies of Microbes
What types of cells can counting chambers be used to count?
Both eukaryotes and prokaryotes.
p.38
Reproductive Strategies of Microbes
What do strict anaerobic microbes lack or have very low quantities of?
Superoxide dismutase and catalase.
p.27
Environmental Factors Affecting Microbial Growth
How do microbes adapt to hypotonic solutions?
They reduce osmotic concentration of cytoplasm by using mechanosensitive (MS) channels in the plasma membrane to allow solutes to leave.
What happens during the log phase of microbial growth?
Cells grow as quickly as they can for the conditions available.
p.19
Reproductive Strategies of Microbes
What does viable counting assess in microbiology?
Whether a cell is alive or dead.
p.7
Chromosome Replication and Partitioning
What role does the replisome play in bacterial chromosome replication?
It unwinds and copies DNA.
p.47
Biofilm Formation and Communication
What types of interactions occur among organisms in a biofilm?
Metabolic exchanges, DNA uptake, and communication.
p.20
Reproductive Strategies of Microbes
What are Spread Plates and Pour Plates used for?
Quantitative methods for counting microorganisms.
p.7
Chromosome Replication and Partitioning
What is the terminus in the context of bacterial chromosome replication?
The point where replication ends.
How is generation time defined?
The time it takes for a microbial population to double in number.
p.24
Reproductive Strategies of Microbes
What is the purpose of the streak plate method?
To isolate individual cells on an agar surface.
p.12
Environmental Factors Affecting Microbial Growth
What factors can influence growth rate?
Nutrient availability, environmental conditions, and genetic factors.
p.45
Biofilm Formation and Communication
Where are biofilms commonly found?
Ubiquitous in nature in water.
p.48
Biofilm Formation and Communication
How does EPS and changes in physiology protect microbes?
It protects them from harmful agents.
What does 'growth' refer to in the context of microorganisms?
The increase in the number of cells in the population.
p.8
Binary Fission Process
What is the first step in the septation process?
Selection of site for septum formation.
How is the growth of microorganisms usually plotted?
As logarithm of cell number vs. time.
What are the two alternative hypotheses for the Death Phase in bacteria?
1. Cells are Viable But Non Culturable (VBNC) - alive but dormant; 2. Programmed cell death - a fraction of the population is genetically programmed to die.
p.48
Biofilm Formation and Communication
What is a potential consequence of organism sloughing from biofilms?
Contamination of the water phase above the biofilm.
p.48
Biofilm Formation and Communication
What does EPS stand for in the context of biofilms?
Extracellular Polymeric Substances.
p.25
Environmental Factors Affecting Microbial Growth
What type of conditions do most organisms prefer for growth?
Fairly moderate environmental conditions.
p.44
Radiation Damage to Microbes
What type of environment can D. radiodurans survive?
Highly radioactive environments.
p.31
Environmental Factors Affecting Microbial Growth
What is the optimal condition for enzyme functioning?
Enzymes have an optimal temperature at which they function best.
What characterizes the Prolonged Decline in Growth of bacterial populations?
The population continually evolves with successive waves of genetically distinct variants.
p.2
Reproductive Strategies of Microbes
What are the methods of asexual reproduction in Bacteria and Archaea?
Binary fission, budding, and filamentous reproduction.
p.21
Viable Counting Methods
How are bacteria trapped in the membrane filter technique?
Bacteria from aquatic samples are trapped on membranes.
What is the significance of understanding generation rates?
It helps in predicting microbial growth and behavior in various environments.
p.23
Continuous Culture Systems
What happens to the dilution rate in a Turbidostat?
The dilution rate varies.
p.6
Chromosome Replication and Partitioning
What is a replisome?
A group of proteins needed for DNA synthesis.
p.50
Biofilm Formation and Communication
What is Acylhomoserine lactone (AHL)?
An autoinducer molecule produced by many gram-negative organisms.
What structure does FtsZ polymerization form?
The Z ring, a meshwork of filaments.
How do MinC, MinD, and MinE contribute to Z ring formation?
They oscillate from one side of the cell to the other, preventing Z ring formation at the poles.
p.43
Radiation Damage to Microbes
What type of organism is D. radiodurans?
Non-spore-forming, obligate aerobic chemoorganoheterotroph.
p.36
Environmental Factors Affecting Microbial Growth
What is the reaction catalyzed by peroxidase?
H2O2 + NADH + H+ → NAD+ + 2H2O.
p.39
Reproductive Strategies of Microbes
What do strict anaerobic microorganisms lack or have in very low quantities?
Superoxide dismutase and catalase.
p.25
Environmental Factors Affecting Microbial Growth
What are some environmental factors that influence microbial growth?
Salts, pH, temperature, oxygen concentration, pressure, and radiation.
p.44
Radiation Damage to Microbes
Why is D. radiodurans significant in microbiology?
It has exceptional DNA repair capabilities.
p.31
Environmental Factors Affecting Microbial Growth
Can microbes regulate their internal temperature?
No, microbes cannot regulate their internal temperature.
p.31
Environmental Factors Affecting Microbial Growth
What effect do high temperatures have on enzymes?
High temperatures may inhibit enzyme functioning and can be lethal.
p.2
Reproductive Strategies of Microbes
What must all microbes do before division?
Replicate and segregate the genome.
p.21
Viable Counting Methods
What is done to the membrane after trapping bacteria?
The membrane is soaked in culture media.
p.22
Continuous Culture Systems
Why is continuous culture important for studying microbial growth?
It allows study at very low nutrient concentrations, resembling natural environments.
p.22
Continuous Culture Systems
What interactions can be studied in continuous culture systems?
Interactions of microbes under conditions resembling those in aquatic environments.
p.3
Binary Fission Process
What happens to the daughter cells after binary fission?
They divide; some species separate completely while others remain attached, forming chains or doublets.
p.30
pH Tolerance Mechanisms of Microbes
What is one mechanism of the acidic tolerance response in microbes?
Pumping protons out of the cell.
p.30
pH Tolerance Mechanisms of Microbes
What types of proteins do some microbes synthesize for protection?
Acid and heat shock proteins.
p.35
Environmental Factors Affecting Microbial Growth
What is an obligate aerobe?
A microbe that requires O2 for growth.
p.43
Radiation Damage to Microbes
What extreme conditions can D. radiodurans resist?
Cold, dehydration, vacuum, acid, oxidation.
p.36
Environmental Factors Affecting Microbial Growth
What is the role of peroxidase in aerobic organisms?
It reduces hydrogen peroxide using NADH.
p.20
Reproductive Strategies of Microbes
How are microbial counts reported in quantitative methods?
As Colony Forming Units (CFU).
Why is measuring generation time important?
It helps in understanding the growth dynamics of microbial populations.
p.40
Radiation Damage to Microbes
What are the effects of ionizing radiation on organisms?
It can cause mutations and death (sterilization).
p.37
Environmental Factors Affecting Microbial Growth
How do anaerobic microbes respond to the presence of oxygen?
Anaerobic microbes may be inhibited or killed by oxygen.
p.37
Environmental Factors Affecting Microbial Growth
What type of microbes can tolerate varying oxygen levels?
Facultative anaerobes can grow in both the presence and absence of oxygen.
What role does natural selection play in the Prolonged Decline phase?
Natural selection drives the evolution of the bacterial population.
What happens to the population growth in the stationary phase?
Population growth ceases, and the total number of viable cells remains constant.
p.46
Biofilm Formation and Communication
What do microbes release to form the extracellular polymeric substance (EPS) during biofilm formation?
Polysaccharides, proteins, and DNA.
p.3
Binary Fission Process
What is synthesized completely through the cell center during binary fission?
The septum, resulting in two chambers.
p.28
Reproductive Strategies of Microbes
What additional requirement do extreme halophiles have?
Extremely high concentrations of potassium.
p.30
pH Tolerance Mechanisms of Microbes
How do many microorganisms affect the pH of their habitat?
By producing acidic or basic waste products.
p.34
Environmental Factors Affecting Microbial Growth
What type of organisms live in deep sea environments with high hydrostatic pressures?
Some Bacteria and Archaea.
p.29
Environmental Factors Affecting Microbial Growth
What does pH measure?
The relative acidity of a solution, defined as the negative logarithm of the hydrogen ion concentration.
What is the generation rate in microbial growth?
The time it takes for a population of microbes to double in number.
p.21
Viable Counting Methods
What is the membrane filter method used for?
To count viable bacteria in aquatic samples.
p.13
Environmental Factors Affecting Microbial Growth
What factors can affect the generation rate of microbes?
Nutrient availability, temperature, and environmental conditions.
p.41
Radiation Damage to Microbes
What is required for UV radiation to cause damage to microbes?
Direct exposure on the microbial surface.
p.41
Radiation Damage to Microbes
How can DNA damage from UV radiation be addressed?
Through several DNA repair mechanisms.
p.41
Radiation Damage to Microbes
What does visible light generate at high intensities?
Singlet oxygen (1 O2), a powerful oxidizing agent.
Where does the highest concentration of MinC accumulate?
At the poles of the cell.
p.25
Environmental Factors Affecting Microbial Growth
What are extremophiles?
Organisms that grow under harsh conditions that would kill most other organisms.
p.26
Environmental Factors Affecting Microbial Growth
What happens to microbial cells in a hypotonic solution?
Water enters the cell, causing it to swell and possibly burst.
p.2
Reproductive Strategies of Microbes
What is the reproductive strategy of Bacteria and Archaea?
They reproduce asexually and are haploid only.
p.8
Binary Fission Process
What occurs during the final step of septation?
Constriction of cell and septum formation.
p.23
Continuous Culture Systems
What is a key characteristic of the nutrient supply in a Chemostat?
An essential nutrient is in limiting quantities.
p.28
Reproductive Strategies of Microbes
What are halophiles?
Microbes that grow optimally in the presence of NaCl or other salts at concentrations above about 0.2M.
What two pathways function during the bacterial cell cycle?
DNA replication and partition, and cytokinesis (septation and daughter cell formation).
What are the reasons for entering the stationary phase?
Nutrient limitation, limited oxygen availability, toxic waste accumulation, and critical population density reached.
What is a critical factor that can lead to the stationary phase?
Reaching a critical population density.
p.15
Nutrient Availability and Growth Limitations
What role does toxic waste accumulation play in microbial growth?
It can contribute to the transition into the stationary phase.
p.34
Environmental Factors Affecting Microbial Growth
What are barotolerant organisms?
Organisms that are adversely affected by increased pressure, but not as severely as nontolerant organisms.
p.36
Environmental Factors Affecting Microbial Growth
What are reactive oxygen species (ROS)?
They include superoxide radical, hydrogen peroxide, and hydroxyl radical.
p.33
Environmental Factors Affecting Microbial Growth
How do thermophiles stabilize their protein structure?
By having more hydrogen bonds, more proline, and utilizing chaperones.
p.26
Environmental Factors Affecting Microbial Growth
What is a hypertonic solution?
A solution with a higher osmotic concentration than the cell.
p.6
Chromosome Replication and Partitioning
What shape do most bacterial chromosomes have?
Circular (covalent loops).
p.26
Environmental Factors Affecting Microbial Growth
What effect do changes in osmotic concentrations have on microbial cells?
They can cause water to enter or leave the cells, affecting their integrity.
p.6
Chromosome Replication and Partitioning
What is the origin of replication?
The site at which replication begins.
p.37
Environmental Factors Affecting Microbial Growth
What is the impact of oxygen on microbial metabolism?
Oxygen levels can significantly influence metabolic pathways in microbes.
What is cytokinesis in the context of the bacterial cell cycle?
The process of septation and daughter cell formation.
p.21
Viable Counting Methods
How is the number of bacteria in a sample determined using the membrane filter method?
By counting the colonies that grow on the membrane.
p.46
Biofilm Formation and Communication
What happens as microbes reproduce in a biofilm?
Additional polymers are produced and the biofilm matures.
p.41
Radiation Damage to Microbes
What role do carotenoid pigments play in microorganisms exposed to light?
They protect many light-exposed microorganisms from photooxidation.
p.50
Biofilm Formation and Communication
What type of organisms primarily produce AHL?
Many gram-negative organisms.
p.35
Environmental Factors Affecting Microbial Growth
What are aerotolerant anaerobes?
Microbes that can grow with or without O2.
p.36
Environmental Factors Affecting Microbial Growth
What protective enzyme do aerobes produce to deal with superoxide radicals?
Superoxide dismutase (SOD).
What are the main phases of the E. coli cell cycle?
Growth phase, DNA replication phase, and division phase.
p.8
Binary Fission Process
What machinery is assembled during septation?
Cell wall synthesizing machinery.
p.18
Reproductive Strategies of Microbes
What is a key advantage of using counting chambers?
They are easy, inexpensive, and quick.
p.31
Environmental Factors Affecting Microbial Growth
What are the distinct cardinal growth temperatures for organisms?
Minimal, maximal, and optimal temperatures.
p.18
Reproductive Strategies of Microbes
What is a limitation of counting chambers?
They cannot distinguish living from dead cells.
p.28
Reproductive Strategies of Microbes
What are extreme halophiles?
Microbes that require salt concentrations of 2M to 6.2M.
p.22
Continuous Culture Systems
In what fields is continuous culture used?
Food and industrial microbiology.
What are two ways to measure microbial growth?
Changes in the number of cells and changes in the mass of the population.
p.35
Environmental Factors Affecting Microbial Growth
What are facultative anaerobes?
Microbes that do not require O2 but grow better in its presence.
p.34
Environmental Factors Affecting Microbial Growth
How do barophilic organisms adapt to high pressures?
By changing their membrane fatty acids.
p.37
Environmental Factors Affecting Microbial Growth
What is the effect of high oxygen levels on aerobic microbes?
Aerobic microbes thrive and grow rapidly in high oxygen levels.
p.40
Radiation Damage to Microbes
How does ionizing radiation affect the chemical structure of molecules?
It disrupts the chemical structure of many molecules, including DNA.
How does the length of the Lag Phase vary?
It can be very short or even absent.
p.37
Environmental Factors Affecting Microbial Growth
What happens to microbial growth in low oxygen environments?
Microbial growth may slow down or be limited in low oxygen environments.
p.50
Biofilm Formation and Communication
How does AHL function in quorum sensing?
It diffuses across the plasma membrane and induces expression of target genes.
What effect does the high concentration of MinC have on Z ring formation?
It prevents the formation of the Z ring at the poles.
p.24
Reproductive Strategies of Microbes
What is visible growth on a streak plate called?
A colony of microorganisms.
p.5
Chromosome Replication and Partitioning
During which phase does DNA replication occur in E. coli?
The DNA replication phase.
p.22
Continuous Culture Systems
What phase do cells maintain in a continuous culture system?
Log phase at a constant biomass concentration.
p.40
Radiation Damage to Microbes
Can damage from ionizing radiation be repaired?
Yes, if the dose is small, damage may be repaired by DNA repair mechanisms.
p.5
Nutrient Availability and Growth Limitations
How does nutrient availability affect the E. coli cell cycle?
Nutrient availability can limit growth and division rates.
p.30
pH Tolerance Mechanisms of Microbes
How do microbes prevent protons from entering their cells?
The plasma membrane is impermeable to protons.
p.6
Chromosome Replication and Partitioning
What happens to the origins during DNA replication?
They move to opposite ends of the cell.
What is the bacterial cell cycle?
A sequence of events from the formation of a new cell through the next cell division.
p.22
Continuous Culture Systems
What is continuous culture of microorganisms?
Growth in an open system with continual provision of nutrients and removal of wastes.
p.3
Binary Fission Process
What is the first step in the binary fission process?
A young cell at the early phase of the cycle.
What triggers the division of E. coli cells?
Completion of DNA replication and cell growth.
p.3
Binary Fission Process
What happens to the parent cell during binary fission?
It enlarges its cell wall, plasma membrane, and volume, and DNA replication starts.
p.23
Continuous Culture Systems
How does a Turbidostat regulate the flow of media?
By maintaining a predetermined turbidity or cell density.
What characterizes the Exponential Phase of microbial growth?
The rate of growth and division is constant and maximal.
p.46
Biofilm Formation and Communication
How do microbes initially attach during biofilm formation?
They reversibly attach to a conditioned surface.
p.50
Biofilm Formation and Communication
What does AHL regulate once inside the cell?
A variety of functions through target gene expression.
p.35
Environmental Factors Affecting Microbial Growth
What is an obligate anaerobe?
A microbe that is usually killed in the presence of O2.
p.34
Environmental Factors Affecting Microbial Growth
What are barophilic (peizophilic) organisms?
Organisms that require or grow more rapidly in the presence of increased pressure.
p.48
Biofilm Formation and Communication
In what systems can sloughing from biofilms contaminate water?
In drinking water systems.
What occurs during the Lag Phase of microbial growth?
Cells synthesize new components to replenish spent materials and adapt to new conditions.
p.23
Continuous Culture Systems
What is the main function of a Chemostat?
To maintain a constant rate of incoming medium equal to the rate of removal from the vessel.
p.26
Environmental Factors Affecting Microbial Growth
What occurs when microbial cells are placed in a hypertonic solution?
Water leaves the cell, leading to membrane shrinkage from the cell wall (plasmolysis).
What are the main stages of the bacterial cell cycle?
Growth, chromosome replication, and cytokinesis.
p.41
Radiation Damage to Microbes
What type of mutations can UV radiation cause?
Thymine dimers in DNA, leading to mutations and potentially death.
p.3
Binary Fission Process
What occurs as the chromosomes move during binary fission?
The septum begins to form.
p.6
Chromosome Replication and Partitioning
What is the terminus in DNA replication?
The site at which replication is terminated, located opposite of the origin.
What occurs to active cells during the stationary phase?
Active cells stop reproducing or the reproductive rate is balanced by the death rate.
p.42
Environmental Factors Affecting Microbial Growth
What extreme conditions can Deinococcus radiodurans survive?
Cold, dehydration, vacuum, and acid.
p.15
Nutrient Availability and Growth Limitations
How does nutrient limitation affect microbial growth?
It can lead to the stationary phase where growth ceases.
p.35
Environmental Factors Affecting Microbial Growth
What is an aerobe?
A microbe that grows in the presence of atmospheric oxygen (20% O2).
p.35
Environmental Factors Affecting Microbial Growth
What is a microaerophile?
A microbe that requires 2-10% O2 for growth.
p.22
Continuous Culture Systems
What is achieved using a continuous culture system?
A constant supply of cells in exponential phase growing at a known rate.
p.21
Viable Counting Methods
What happens after the membrane is soaked in culture media?
Colonies grow on the membrane.
p.23
Continuous Culture Systems
What is a significant difference between a Chemostat and a Turbidostat regarding nutrient limitation?
A Chemostat has limiting nutrients, while a Turbidostat does not.
p.28
Reproductive Strategies of Microbes
Why do halophiles need high salt concentrations?
To maintain stability and activity of their cell wall, proteins, and plasma membrane.
p.35
Environmental Factors Affecting Microbial Growth
What determines growth in different oxygen concentrations for microbes?
It depends on a microbe’s metabolic processes, electron transport chains (ETC), and the terminal electron acceptor used.
p.35
Environmental Factors Affecting Microbial Growth
What is an anaerobe?
A microbe that grows in the absence of O2.
