Chapter 6 Flashcards
4 Major Environmental conditions that influence growth
- Temperature
- Oxygen/other gases
- pH
- Water availability
cell division process used by most
bacteria
binary fission
T or F Budding is used by many bacterial species
false
The 3 PHYSICAL requirements for microbial growth?
– Temperature
– pH
– Osmotic pressur
Define extremophiles and what domain does it belong to?
organisms that live in extreme conditions
Archaea
What are the 5 chemical requirements for microbial growth
– Carbon
– Nitrogen, sulfur, and phosphorous
– Trace elements
– Oxygen
– Organic growth factors
- At minimal temparature what is the consistency of the membrane?
- what cardinal temperature are enzymatic reactions occuring at maximal possible rate?
- what cardinal temparature is protein denaturation, collapse of cytoplasmic membrane, thermal lysis?
- gel-like
- optimum
- maximum
What happens at optimum temperatures?
cell components function at max rate
Most bacteria grow best between pH ____ and ____. Molds and yeasts grow better between pH _____ and ______.
Bacteria: pH 6.5-7.5
Molds & Yeasts: pH 5-6
- _____________grow in acidic environments
- _____________ grow in alkaline environments
- Acidophiles
- Alkaliphiles
What does growth media in lab use to minimize pH?
buffers
Neutrophile (pH > ___ and < ___)
___________ (pH < 5.5)
Alkaliphile (pH ≥ __)
Neutrophile (pH > 5.5 and < 8)
Acidophile (pH < 5.5)
Alkaliphile (pH ≥ 8)
what happens when you put an acidophile in neutral solution?
the acidophiles lyse (protons required for stability)
What will happen if you put a bacterial cell in a hypertonic solution and why?
hypotonic solution?
which solution has a positive water balance?
The cell will shrink because water will move out of cell
The cell will swell because water will move into the cell
hypotonic
Is optimal pH intracellular or extracellular?
Extracellular only
Extreme acidophiles and alkaliphiles maintain what?
maintains cytoplasmic pH near neutrality.
T/F Microbial culture media typically contain buffers to
maintain constant pH
TRUE
Bacteria that require high salt for cell growth are called what?
Halophiles (2-5% NaCl)
* Seawater contains ~3% NaCl
- ___________________ REQUIRE high salt
concentration (as high as 30% NaCl) - ____________________ TOLERATE (can grow in presence or absence) high salt
concentrations (2–10% NaCl)
- Extreme/ obligate halophiles
- Facultative halophiles
which elements are ~96% of dry weight of bacterial cell and required by all life?
C, H, O, N, P, S
Mostly proteins and RNA are dry
weight of a bacterial cell not DNA,
WHY?
DNA is the script that the cell USES to synthesize RNA and proteins
Nitrogen is a component of what 3 things?
- proteins
- DNA
- ATP
_____________: Use organic carbon as nutrient source
____________: Use inorganic carbon (CO2) as carbon source
Heterotrophs
Autotrophs
which element is used in DNA, RNA, ATP and membranes (phospholipids)?
phosphorus
Sulfur is a component of what 2 things?
- amino acids
- vitamins
Trace elements are used by cells as what?
enzyme cofactors
(word bank: anoxic, obligate anaerobes, aerotolerant, obligate aerobes, microaerophiles, facultative anaerobes)
- Obligate _________: absolutely require oxygen
– grow at full O2 tension (~21%) and respire O2 - ___________ anaerobes: able to grow with or without oxygen
– grow via fermentation or anaerobic respiration when oxygen is
NOT available - ___________ anaerobes: can’t use oxygen and most are harmed by it
- _____________: can tolerate but can’t use oxygen
- _________________:
can use O2 only at levels reduced from that in air (microoxic) due to limited respiration or oxygen sensitivity - ________ (oxygen free) habitats: mud, bogs, marshes, animal intestines, other diverse habitats
- Obligate aerobes
- Facultative anaerobes
- Obligate anaerobes
- Aerotolerant
- Microaerophiles
- Anoxic
which organisms have high O2 concentration in the oxic zone?
which organisms have high O2 concentration in both the oxic and anoxic zone?
Obligate aerobes, Microaerophiles
Facultative anaerobes, Aerotolerant anaerobes
Why is oxygen toxic?
forms toxic byproducts inside phagolysosome in phagocytes. (superoxide anion, hydrogen peroxide, peroxide anion, hydroxyl radical)
What Contains chemicals (e.g. sodium thioglycolate) that combine with O2 to deplete it?
Reducing media (reducing agent added)
Toxic forms of Oxygen
- Superoxide dismutase
- Catalase (converts hydrogen peroxide to water and oxygen)
- Peroxidase
What dye does thioglycolate medium use that turns pink/red in the presence of oxygen?
Resazurin
How do bacteria communicate cell to cell?
via quorum sensing
- growth in suspension of free floating/free-swimming cells?
- attached to surface, can develop
into biofilms
- Planktonic growth
- Sessile growth
What does bacteria secrete to attract other bacterial cells?
an inducer (signaling chemical)
Biofilm growth is ________x resistant to microbicides/antimicrobials
1000x
what formation begins when planktonic bacteria attach to surfaces. Other bacteria attach and grow on initial layer?
biofilm formation
In nature prokaryotes live in what type of communities?
mixed communities
Biofilms and humans
- what percent of infections are biofilms involved in?
- biofilms can form on what 3 things?
- biofilms are responsible for cavities and causes what disease?
- T/F biofilms do not corrode
- 70%
- catheters, heart valves, contact lenses
- gum disease
- FALSE, they corrode
What are microbial mats and give an example?
multilayered sheets w/ dfferent organisms in each layer
- hot springs
In binary fission, growth is defined as?
Cell growth is ____________, meaning population doubles with each cell
increase in the # of cells,
NOT size
exponential
During cell division, each daughter cell receives a chromosome and what, in order to exist as an independent cell?
sufficient copies of all other cell constituents
how do prokaryotic cells divide?
binary fission
What is the partition between dividing cells?
- pinches off two daughter cells
septum
Define batch culture
a closed-system microbial culture
of fixed volume
Typical growth curve for population of cells grown in a closed system is characterized by what four phases?
1.Lag phase
2.Exponential or log phase
3.Stationary phase
4.Death phase
Lag phase of microbial growth:
Period of 1. _____________ growth
* 2. _________ of population with each
generation
* Growth at a constant rate
* Cells are metabolically identical
* Produce 3. ________ metabolites
- exponential growth
- doubling
- primary metabolites
What phase is the interval between inoculation of a culture and beginning of growth?
in this phase, does the # of cells increase, decrease, or neither?
– What do cells prepare for in this phase?
“tooling up” for rapid
growth is defined as what?
What is needed in this phase before growth can begin?
Lag phase
NEITHER (does not increase)
cells prepare for growth
Intense metabolic activity
1.biosynthesis of new enzymes
2. required metabolites
what 3 things happens during the Late log phase of microbial growth?
- Synthesize secondary metabolites
- enhance survival
- make antibiotics
which type of measurement is used for:
–count microbial cells
▪ Direct microscopic count
▪ Plate count
▪ Filtration
▪Most probable number (MPN) method
direct measurement
What phase does growth slows as carrying capacity is approached?
– Cell deaths balances #s of new
cells
– Overall population remains
relatively _________
statonary phase
stable
What phase is described below?
* Total number of viable cells decreases
* Decrease at constant rate
* Death is exponential (logarithmic)
* Much slower rate than growth
Death phase
which type of measurement is used for:
–doesn’t count microbial cells
▪ Turbidity
▪Metabolic activity
▪ Dry weight
indirect measurement
Direct microscopic cell count uses what to count cells?
Petroff-Hausser cell counter
Two main ways to perform viable (plate) counts
▪ ________-____ method: bacteria mixed into a dish with agar
▪ ____-_____ method: bacteria spread on the surface of an agar plate
1.pore-plate method
2. spread- plate method
What are limitations of direct microscopic cell count?
Great Plate Count Anomaly
- you can see more on microscope and less on the plate because only live cells are visible
- Count colonies on plates with __–____ colonies
- To ensure the right number of colonies, the original inoculum must be diluted via _____ _______
- Report in ______-_______ _____ (CFU) instead of number of viable cells accounts for clumps.
- 30-300
- serial dilution
- colony-forming units
how do you calculate number of bacteria per ml in direct microscopic count?
(# of cells counted)/ Vol. of area counted
Serial dilutions:
A: 10^-2
B: _____
plates: 10^-4
______
C:10^-6
plates: ______
______
A: 10^-2
B: 10^-4
plates: 10^-4
10^-5
C:10^-6
plates: 10^-6
10^-7
which element stabilizes ribosomes, membranes, and nucleic acids. Also required by many enzymes (co-factor)
magnesium
Define plasmolysis
shrinkage of cells cytoplasm
1._______________
(cold loving)-5°C to 15°C
* Found in Arctic and Antarctic regions
2. ________________
0°C to 30°C
* Important in food spoilage in refrigerator
3. ________________ (moderate temperature loving)
10°C to 45°C
* More common
* Disease causing
* Normal microbiota
4. ____________________
45°C to 70°C
Common in hot springs
5.____________________(extreme thermophiles)
70°C to 110°C (even upto 122°C)
* Usually members of Archaea
* Found in hydrothermal vents & organic compost piles
- psychrophiles
- psychrotrophs
- mesophiles
- thermophiles
- hyperthermophiles
