Microbial Growth Flashcards
How is microbial growth measured?
Increase in mass and numbers
Microbes grow by ______.
binary fission
Microbial growth is ________.
exponential
What is the consequence of binary fission?
single cell divides into two identical daughter cells (clones)
All cells in a population are _____ of the original?
clones
TRUE or FALSE? Rapid population growth is possible.
TRUE
Within the mechanics of binary fission will increase in….
Cell contents
Length
Cell Volume
Cytoplasmic contents
Lengthening of cell wall
DNA replication
What are the steps in cell division?
- Chromosomes separates into two cells
- The FtsZ ring forms in the middle Divisosome complex
- Contraction of the FtsZ ring guides septum formation
- Cells deficient in FtsZ fail to septate
Binary fission is not the only method of cell division what are other methods?
- Simple budding
- Budding hyphae
- Cell division of stalked organism
- Polar growth without differentiation of cell size
Single celled fungi are called what?
Yeasts
Multicellular fungi have weblike bodies called _______.
Mycelia
Both the reproductive structure and mycelium are composed of ____.
Hyphae
How do we measure microbial growth?
- Cell Division
- Population growth
What are some requirements in studying microbes in the lab in pure culture?
- Must isolate microbe away from all other organisms
- Must be able to grow in the laboratory
- Then can measure growth and study growth
What are ways to measure cell number?
directly by counting
Indirectly by plating
Indirectly by turbidity
When doing total counts what counter should you use?
Petroff-Hauser Counter
When doing electronic counter of particles what counter should you use?
Colter counter
What is the stages of the growth of population?
- Lag phase
- Log phase
- Stationary phase
- Death phase
When one cell becomes two it forms a _____.
Generation
Growth rate measures what?
Generations per time in log phase
What are some growth conditions that can affect growth rate?
- Nutrient availability
- Environmental factors
What is planktonic growth?
Bacteria separate, floating in solution
How do biofilms work?
Live in groups, surrounded by macromolecular matrix
What are the advantage of biofilms?
- Protection from predators
- Protection from harmful chemicals
- Protection from radiation and heat
What are the disadvantages of biofilms?
Poorer access to nutrients
Waste buildup
What are the steps of biofilm formation?
- Attachement
- Polymerization
- Expansion
For microbes internal temperature = ______.
Outside temperature
What happens on the low end of the temperature range?
Enzyme rate slows down
Cell membrane solidifies
On the low end of the temperature range are changes likely to be reversible?
Yes!
What happens on the high end of the temperature range?
Cellular changes
On the high end of the temperature range are changes likely to be reversible?
No
What are habitats for thermophiles?
hot springs, artificial thermal sources, hydrothermal vents, compost piles
What are adaptations include what…..
heat-stable proteins and saturated fatty acids in lipids and ether linked lipids
Thermophiles include what….
Bacteria, Archaea, and some Eukarya
What are habitats of psychrophiles?
Arctic and Antarctic regions, glaciers, high altitudes, oceans, caves, refrigerators, atmospheres
What are adaptations of psychrophiles?
Cold-stable enzymes, unsaturated and polyunsaturated fatty acids and lipids
Psychrophiles include what…..
Bacteria, Archaea, and Eukarya
What pHs are compatible with life?
6,7,8
What are habitats of acidophiles?
acid mine drainage, acid hot springs, volcanic soils, acidic soils, geothermal vents
TRUE or FALSE? Acidophiles also live in parts of the mammalian GI tract?
True
Acidophiles include what…..
Bacteria, archaea, and fungi
What are habitats of alkalophiles?
Soda lakes and alkaline soils
TRUE or FALSE? alkalophiles also live in parts of the mammalian GI tract?
TRUE
Alkalophiles include….
Bacteria and Archaea
Things that grow with decreased water availability are called….
Xerophiles
Things that grow with increased water availability are called what?
halophiles
Cells accumulate ________ to combat ________.
compatible solutes, osmotic stress
Organisms that grow in oxygen must have means to deal with what?
Oxygen byproducts
Define the following…
a. Anaerobes
b. Microaerophilic
c. Aerobes
a. No oxygen
b. Low oxygen
c. high oxygen
what are some examples of inclusions?
Sulfur storage
Phosphate storage
What is the purpose of sulfur storage?
Microbes that use sulfur as energy storage can accumulate large quantities intracellularly or extracellularly
What is the benefit of phosphate storage?
Phosphate is stored as poluphosphate
What are the common elements that limit growth?
C, N, P
What are different ways cells sense impending nutrient limitation?
- Hibernation approach
- Seed approach
- Communal behavior
Several starvation conditions increase what sigma factor?
RpoS (Regulator Protein)
What power does Rpos have?
- Alters expression of many genes
- More capable of survival
What are various changes that happen during stationary phase changes?
- Morphological changes (rigid cell envelope)
- Nucleoid changes
- Metabolic changes
- Translational change
What microbes form cysts?
Giardia
What is a response to nutrient deprivation?
Endospore formation
What are some different types of endospores?
- Terminal Spores
- Subterminal Spores
- Central Spores
Is the decision to sporulate reversible?
Irreversible decision
What is the trigger for sporulation?
Limiting nutrients
High cell density
No single signal is the trigger
What is required to sporulate?
Relay of regulatory proteins that involves sigma factors
Cell asymmetry is essential for what….
sporulation
Describe the spore structure?
Genome as central core
Dehydrated
Water complex is with Ca2+ dipicolinic acid
Inner Spore membrane
Germ cell wall
Cortex - peptidoglycan
Outer spore membrane
Coat - protein matrix
Spores are ____ cells
dormant
What are some characteristics of spores?
- Multiple layers of protective materials
- Very low metabolic activity
- Partially dehydrated
- Highly stable
- Germination requires special conditions not just “good” growth conditions
When do spores germinate?
When cell senses favorable conditions
What happens during spore germination?
Germinant receptor proteins in inner spore membrane. Vegetative cell is reconstituted
Germination of spores is usually triggered by what?
Nutrients of low molecular weight (species and strain specific)
Vegetative cells are _____.
Filaments
Outer membrane of some cyanobacteria is ____, ____ too.
shared, periplasm
Hormogonia are ____, for dispersal and symbiosis.
motile
Akinetes are for _______ conditions?
unfavorable conditions
When are heterocycsts helpful?
under limiting nitrogen
What are the steps of heterocysts during limiting nitrogen?
- Terminal differentiation
- 1 in 10 cells turn into heterocyst
- Forms thickened cell wall - protect nitrogenase O2
- Stops phototrophic oxygen generation and CO2 fixation
- Fixes nitrogen and exports
What are akinetes?
Cells that contain carbon and nitrogen storage molecules and thickened cell wall that reduce metabolic activity and are induced under light limiting or phosphate limiting conditions
What is the cycle of myxobacteria response to nutrient deprivation?
- Free living cells
- Starvation
- Aggregation
- Fruiting body
- Spore dispersal
What are hormogonia?
highly motile small filaments formed by cell division without increase in biomass and move by gliding motility
Myxospores are _____ resistant to _____ conditions.
Fairly
harsh
Why are viruses important?
controlling populations
What are 3 types of predatory bacteria?
- Bdellovibrio
- Daptobacter
- Myxobacteria
What are eukaryotic parasites?
portists and bacteriovore animals
What are various strategies to avoid predation?
- Size Reduction
- Cell wall structure
- Morphology
- Exoploymer formation
- Communication
- Toxin release
- Motility patterns
Why is the nitrogen cycle important?
Crop growth
Most nitrogen gas is _____.
inaccessible - 78% of atmosphere
Nitrogen is _____ in most enviornments.
limiting
What are key processes and prokaryotes in the nitrogen cycle?
- Nitrification
- Denitrification
- N2 fixation
- Anammox
Nitrogen fixation common goal is reduction of ____ to _____.
N2 to NH3
In assimilation ammonia is used for what?
cellular nitrogen
What are examples of nitrogen fixation in nature?
- Lightening and UV light
- Bacteria and Archaea
What process of nitrogen fixation greatly increased availability of useable nitrogen?
haber-bosch process
What are some examples of nitrogen fixing partnerships?
- Rhizobia and legumes
- Cyanobacteria and Azolla
- Frankia and various tree species
- shipworms and nitrogen fixing symbionts
- Termites and nitrogen fixing symbionts
Nitrification is……
Conversion of ammonia to nitrate as electron donor for respiration
What classification of bacteria participate in nitrification?
Several species of bacteria and few archaea
What is the two step process of nitrification?
- conversion of ammonia to nitrite
- conversion of nitrite to nitrate
What are examples of ammonia oxidizing bacteria?
- Extra internal membranes to house respiratory components
- Oxygen is the electron acceptor a type of aerobic respiration
What is denitrification?
conversion of nitrate to nitrogen gas as an electron acceptor for respiration.
Denitrification involves what type of bacteria?
Facultative anaerobes (use oxygen when available)
Denitrification gene expression is controlled by what?
Oxygen and by nitrate
in the US how much of the food supply is lost?
30-40%
In what situations would we want to limit the growth of microbes?
- In the lab
- In our food
- In our water
- In medical situations
- In agriculture
- Industry\
What are the different methods of control for microbial growth?
- Physical antimicrobial control
- Chemical Antimicrobial Control
- Antibiotics
What is the def of sterilization?
kills all viable organisms including endospores
What is the def of disinfection?
removal of pathogens from inanimate surfaces, may not eliminate all microbes
What is the def of antisepsis?
removal of pathogens from living tissue, may not eliminate all microbes
What is the def of sanitation?
removal of pathogens to safe level
Pasteurization is NOT ______.
Sterilization
What is the difference of batch pasteurization, flash pasteurization, and ultra high temperature sterilization?
Batch pasteurization heats to 66 degrees celcusis for 30 mins. Flash pastuerization passes milk through heat exchanger increase 72 degrees celcusis for 15 seconds then rapid cool down. ultra high temp sterilization is 140-150 degrees celcusis for a few seconds then its sterile
What is the point of ionizing radiation?
kills microbes by damaging DNA and proteins UV rays do not penetrate much
What are types of filter sterilization?
a. Depth filters
b. Membrane filters
c. Nucleopore filter
What is filter sterilization?
filtration avoids heat for sensitive liquids (small pores prevent microbe passing, liquid or gas pass through
Filtering removes microbes based on what _____.
Size
What filter do you use for smaller volumes?
Syringe filter
What filter do you use for larger volumes?
Vacuum filter
What are some examples of control of microbes in food?
- Acids : pickling
- Alcohols
- Sugar and Salt
- Other chemicals
What are chemical biocides?
Toxic chemicals that are nonspecific for their target organism. They chemically modify or denature DNA, proteins, and dissolve or disrupt membranes
What are ways antibiotics control microbial growth?
Antibiotics are narrow range chemicals used to selectively target one type of organism
