Module 4.2 Flashcards
What is the pH range of each classification of organisms based on pH?
Acidophiles < pH 5.4
Neutrophiles pH 5.4 - 8.5
Alkaliphiles pH 7.5 - 11.5
are acid-loving organisms.
< pH 5.4
Acidophiles
acidophiles
(pH 6)
(pH 2 or less)
(pH <4) sulfur-oxidizing bacteria
(negative pH values) archaea
Lactobacillus
Helicobacter pylori
Acidithiobacillus
Sulfolobus and Thermoplasma, Picrophilus
pH 5.4 - 8.5
most human disease-causing bacteria (human blood and tissues pH = 7.2 – 7.4)
protozoans and most bacteria (pH 6.5-7.5)
neutrophiles
neutrophiles
bacteria in gut
protozoan in human large intestines
bacteria on tissue surface
skin infection
- E. coli
- Balantidium coli
- Salmonella
- Staphylococcus
base-loving organisms
live in soda lakes, high-carbonate soils
pH 7.5 - 11.5
alkaliphiles
pH 7.5 - 11.5
Bacillus
Vibrio cholerae (pH 9),
Alcaligenes faecalis (>pH 9),
Agrobacterium (pH 12)
Alkaliphiles
three critical temperatures (affecting enzyme
function) or cardinal temperatures:
minimum growth temperature
optimum growth temperature
maximum growth temperature
Temperature Classes of Microorganisms
Psychrophiles: <0 to 20, 15
Mesophiles 10 to 48, 37
Thermophiles 40 to 72, 60
Hyperthermophiles 65 to 110, 80
Psychrophiles
obligate psychrophiles <20 ̊C
acultative psychrophiles
snow alga
Sporosarcina globispora
Xanthomonas pharmicola
Chlamydomonas nivalis
Psychrophiles
that is present in raw milk and a variety of process meat,
can grow even in cold temp of refrigerator (can multiply at -4.4 ̊C),
can be killed by cooking and pasteurization
Listeria monocytogenes
Mesophiles
thermoduric microorganisms
Bacillus, Micrococcus, Lactococci, Corynebacterium
obligate thermophiles
facultative thermophiles
Geobacillus stearothermophilus
Bacillus coagulans (35-50 ̊C), B. licheniformis
examples of _________:
archaeobacteria (deep-sea vents, 115 ̊C)
Pyrolobus fumarii (“firelobe of the chimney”) – (113 ̊C)
Thermus aquaticus
Hyperthermophiles
Preventing Growth Using Temperature:
refrigeration (4 ̊C) - refrigerator
long-time storage (-30 ̊C) - ultra-low freezer
high temperatures - pressure cooker
Tolerating Low and High Temperatures
unsaturated (polyunsaturated) fatty acids in phospholipids
with enzymes functional at low temperatures
active transport occurs well at low temperatures
Psychrophiles
Tolerating Low and High Temperatures
saturated fatty acids in phospholipids
heat-stable proteins and enzymes
thermophiles
Tolerating Low and High Temperatures
no fatty acids in their membrane (phytane)
lipid monolayer
- in some species, the opposing phospholipid tails are joined into a single tail, forming a monolayer that _______ the membrane at high temperatures
Hyperthermophiles,
stabilizes
microorganisms can be classified as (based on oxygen chuchu)
obligate aerobes - Pseudomonas
obligate anaerobes - Bacteroides, Clostridium methanogens
microaerophiles - Treponema pallidum
facultative anaerobes - Staphylococcus and E. coli
aerotolerant respiration - Lactobacillus (captures energy by fermentation)
molecule which is the reason why oxygen toxic to
some microorganisms
superoxide
Anaerobic Culture Methods (How) (5)
- Use reducing media, containing chemicals that combine with O2
- Use anaerobic jar (GasPak)
- Novel method in clinical labs: Add oxyrase to growth media (OxyPlate)
- Work in a glove box
- Use candle jars
essential ingredient of bacterial protoplasm.
is needed by actively metabolizing cells
Water
Effect of drying varies:
- Treponema pallidum –
- Staphylococcus sp. –
- endospore-former bacteria and xerophiles –
- highly sensitive
- can stand for months
- resistant to desiccation
– minimum pressure needed to be applied to a solution to prevent the flow of water across a semi-permeable membrane
osmotic pressure
environment/osmotic solution for optimum growth
isotonic/hypotonic environment
environment that causes plasmolysis, water loss, inhibits growth
hyperosmotic environment
application: use of salt or sugar as preservative (4)
salting of fish
sugaring of fruits
brining of vegetables
jams, marmalades, preserves, and pickles
organisms that can grow at relatively high salt concentration (up to 10%)
osmotolerant
salt-loving organisms; require relatively high salt concentrations for growth (i.e. archea require NaCl concentrations of 20 % or higher)
have transport systems to regulate movement of substances
require moderate to large quantities of salt
typically found in the ocean (optimum: 3.5% salt concentration)
found in exceptionally salty bodies of water (Dead Sea, brine vats)
halophiles
halophiles classification
low halophiles – 1-6% NaCl
mild or moderate halophiles – 6-15% NaCl
extreme halophiles – 15-30% NaCl
halophile that is thriving in the Dead Sea
Dunaliela salina
pressure exerted by standing water, in proportion to its depth
- doubles with every 10 meter increase in depth
hydrostatic pressure
bacteria that live at high pressures
- membranes and enzymes (3-D configuration) require high pressure to function properly
- exhibit optimal reproduction rates at hydrostatic pressures exceeding 10MPa, found throughout the deep-biosphere
piezophiles (barophiles)
In ____, all known bacterial piezophiles fall into this category. They exhibit optimal reproduction rates at hydrostatic pressures exceeding 10MPa and at temperatures ranging from 2-4°C, found throughout the deep-biosphere
Psychropiezophiles
With ____, the only current example is the archaeon Pyrococcus yayanosii. They exhibit optimal reproduction rates at 52MPa and 98°C.
Thermopiezophiles
With ____, visible light is the source of energy for photosynthesis (photosynthetic microorganisms: Cyanobacteria, Volvox).
Radiation/Radiant Energy
What is the difference between Direct Damage and Indirect Damage by ionizing radiation?
Direct Damage - Direct sa DNA
Indirect Damage - muagi pag laing molecule (superoxide)
How do most bacteria reproduce?
Binary Fission
What happens in binary fission? (5)
- replication of chromosomes
- cells double in size
- septum formation
- completion of septum with formation of distinct walls
- cell separation
interval for the formation of two cells from one cell
generation
interval of time between for two cells to form from one cell
the time required for a bacterium to give rise to 2 daughter cells under optimum conditions
Generation Time
Generation Time of the ff:
1. Escherichia coli - ___
2. Staphylococcus aureus - ___
3. Mycobacterium tuberculosis - ___
4. Treponema pallidum - ___
Escherichia coli - 20 mins
Staphylococcus aureus - 27-30 mins
Mycobacterium tuberculosis - 792-932 mins
Treponema pallidum - 1980 mins
formulas for generation time and everything
k = number of generations that occur per unit time in
an exponentially growing culture
N = final cell number
No = initial cell number
n = no. of generations that have occurred during the period of exponential growth
g = generation time
t = hours or minutes of exponential growth
N = No2^n
g = t/n
n = (log N- log N0) / log 2
k = ln 2 / g
What are the four phases of bacterial growth curve? (4)
- Lag Phase - maximum cell size towards the end of lag phase.
- Log Phase - smaller cells, stain uniformly.
- Stationary Phase - irregular staining, sporulation and production of exotoxins.
- Phase of Decline - involution forms (with aging).
In the ____ phase,
- NO significant or immediate increase in cell numbers
- there may be an increase in the size of the cell
- ADAPTATION phase
- is metabolically ACTIVE
- the period when microorganisms are introduced into fresh culture medium
Lag
In the ____ or ____ phase, cells start dividing and their number increases exponentially.
- organisms divide at their most rapid rate
- population of organisms DOUBLES in each generation time
- HEALTHIEST state
- Here, bacteria are MORE SUSCEPTIBLE to antibiotics.
Log (Logarithmic); Exponential
In the ____ phase,
- cell division decreases due of nutrients and accumulation of toxic products; inadequate oxygen supply; pH change.
- Here, growth rate TAPERS OFF.
- Equilibrium EXISTS between dying cells and the newly formed cells (new cells produced at the same rate as old cells die).
- Cell functions continue.
- production of secondary metabolites (small, bioactive molecules) occur.
Stationary
n the ____ phase, the population decreases due to the DEATH of cells.
Here, conditions in the medium become less and LESS SUPPORTIVE of cell division.
The number of live cells DECREASES at a logarithmic rate (but slower).
Cells undergo LYSIS or INVOLUTION (assume a variety of unusual shapes).
There are also more spores than vegetative cells that survive.
Decline (Death)
