Microbial Growth Flashcards
What are the two different requirements for microbial growth?
physical and chemical requirements
What are the three physical requirements for microbial growth?
temperature, pH, osmotic pressure
What is the minimum growth temperature?
lowest temperature an organism can grow
Want is the optimum growth temperature?
temperature at which an organism grows best
What is the maximum growth temperature?
highest temperature an organism can grow
What is the temperature range of a psychrophile?
15C or less
What is the temperature range of a psychotroph?
15-25C
What is the temperature range of a mesophile?
25-45C
What is the temperature range of a thermophile?
45-65C
What is the temperature range of a hyperthermophile?
80C or higher
What is pH?
acidity or alkalinity of a solution
What is the pH range of acidophiles?
pH below 6.5
What is the pH range of neutrophiles?
6.5-7.5
What is the pH range of alkalinophiles?
about 7.5
What is osmotic pressure?
pressure due to osmosis
What are the three types of environments?
hypotonic, isotonic, hypertonic
In a hypotonic environment water moves ____ causing ___.
into the cell; lysis
In an isotonic environment water moves _____ resulting in ____.
both in and out of the cell equally; no change
In a hypertonic environment water moves ____ resulting in ____.
out of the cell; plasmolysis
What is plasmolysis?
shrinking of cytoplasm
Where can facultative halophiles grow?
They can grow in 2-15% NaCl, but do not require it
What do obligate halophiles require?
9-30% NaCl
What is carbon?
the structural backbone of living matter
What is carbon required for?
synthesis of all organic compounds in a cell
What is nitrogen required for?
synthesis of protein and nucleic acids
What is sulfur required for?
synthesis of certain proteins
What is phosphorus required for?
synthesis of nucleic acids and phospholipids
What are trace elements required for?
certain enzymes to function (cofactor)
What are examples of trace elements?
minerals, iron, copper and zinc
What are organic growth factors?
organic compounds the organism cannot synthesize
What are examples of organic growth factors?
vitamins, amino acids
What does aerobic respiration require?
oxygen
Aerobes use ____.
oxygen
Anaerobes do not use _____.
oxygen
Obligate aerobes require _____.
oxygen
Microaerophiles prefer high ____ and low ___.
CO2, O2
What percentage of CO2 to microaeropiles prefer?
5-10%
Obligate anaerobes cannot tolerate the presence of ____.
Oxygen
Aerotolerant anaerobes……….
cannot use O2, but can tolerate it
Faculative anaerobes …….
can grow with or without oxygen but prefer oxygen
What is culture media?
nutrient suspension used to cultivate microbes
What is liquid media considered?
a broth
What does solid media contain?
agar
What is agar?
a solidifying agent
What are the two anaerobic growth methods?
reducing media and anaerobic jar
What is reducing media?
media containing chemical reagents that remove O2.
What is the use of reducing media?
culturing anaerobes in tubes, determining O2 requirement
What is an example of reducing media?
Fluid Thiogycollate Medium (FTM)
What is an anaerobic jar?
chamber containing chemicals that remove O2
What is the use of an anaerobic jar?
culturing/isolating anaerobes on plates
How do bacteria reproduce?
binary fission
What are the steps of binary fission?
- cell elongates, DNA is replicated 2. cell wall and membrane form septum 3. cells and DNA completely separate= 2 genetically identical daughters
What are the four parts of the bacterial growth curve?
- lag phase 2. log/exponential growth phase 3. stationary phase 4. death/decline phase
What is the lag phase?
adjustment to new environment, making new enzymes, not yet replicating
What is the log/exponential growth phase?
metabolically active and reproducing exponentially
What is the stationary phase?
replicating rate= death rate, nutrients low, waste high
What is the death/decline phase?
waste becomes more toxic, death rate > replicating rate
What is the generation time?
The time it takes for one cell to become two cells
When can the generation time be calculated?
during the log phase
What are the two types of unusual bacteria?
- Chlamydiae 2. Rickettsiae
What are the two characteristics of Chlamydiae?
obligate intracellular parasites, Lack ATP machinery
What are the two forms of Chlamydiae?
Elementary body and reticulate body
What is the elementary body of Chlamydiae?
infective form; phagocytised by host
What is the reticulate body of Chlamydiae?
reproducing form; replicated inside host using the hosts ATP
What are the two characteristics of Rickettsiae?
- obligate intracellular parasites 2. extremely permeable cell membrane
What do Rickettsiae bacteria do inside host cell?
replicates inside host cell using host rick cytoplasm
What hosts do Rickettsiae bacteria infect?
humans and anthropoids (ticks, lice, fleas, mites)
What is a direct measurement of growth and two examples?
cell and colony counts; counting chambers, plate counts
What are indirect measurements of growth and three examples?
quantifying changes; turbidity, metabolic activity, dry weight
What are counting chambers?
cells physically counted
What are plate counts?
- culture serially diluted 2. plated on several plates 3. colonies counted to calculate CFU in original sample
What is turbidity?
cloudiness indicate increased growth; spectrophotometer used to measure turbidity
What is measure during metabolic activity?
metabolic product (acid or gas); the more product produced, the more bacteria present
How is dry weight measured?
1.samples dehydrated 2. weighed to determine amount
