1.2 Bacterial Growth and Nutrition Flashcards
Decomposition of nitrogen-containing compounds
Nitrogen fixation
Process of Bacterial Cultivation (7)
- Isolation and identification of organisms 2. Determination of antibiotic assay 3. Antibiotic and vitamin assays 4. Biological testing of products destined for human use 5. Food and water analysis 6. Industrial testing 7. Environmental control
MEASUREMENT OF POPULATION GROWTH
- CELL NUMBER/CELL COUNT 2. CELL MASS
Physical Requirements of Microbes
- Temperature 2. Atmosphere 3. Hydrogen ion concentration (pH) 4. Osmotic pressure 5. Hydrostatic pressure
the most rapid cell growth occurs at what part of the culture?
Edge
type of cell mass determination used in fungi
Direct
Log phase continues until one of two things happens
- nutrients in the medium become exhausted 2. toxic metabolic products accumulate and inhibit growth
is defined as the time (t) per generation
Generation time
organisms that thrive at >80°C (70°C to 110°C)
HYPERTHERMOPHILES
Useful in public health microbiology especially in determining water quality
SELECTIVE/DIFFERENTIAL MEDIA
Operates best at high dilution rates and Culture medium lacks a limiting nutrient
Turbidostats
Example is: fungi best grows on bread, dry rot of wood, survival of bacterial endospores
XEROPHILES/XEROTOLERANT
Used to identify lactose-fermenting gram negative bacteria like E. coli
MacConkey Agar/DIFFERENTIAL MEDIA
Phase when cells may be growing in volume or mass, synthesizing enzymes, proteins, RNA; only increase in metabolic activity
Lag Phase
lack superoxide dismutase and catalase
ANAEROBES
electron acceptor in aerobic respiration
Oxygen
14% of phospholipid layer of cell membrane (dry weight)
Nitrogen
at the most favourable temperatures for growth, the number of cell divisions per hour (growth rate) generally doubles for every increase of __°C
10°C
Most stable and effective at lower dilution rates
Chemostats
serves as cofactor for enzymes, complexes with ATP and stabilizes ribosomes and cell membranes
Magnesium
Chemically undefined, prepared from natural products
Complex Media
Examples are Petroff-Hauser, hemocytometer, Coulter counter
Direct Cell Counting
do not require oxygen for growth → may use it for energy yielding chemical reactions
FACULTATIVE AEROBES
optimal T for pathogenic organisms
37°C
The microbial mixture is transferred to the edge of an agar plate with an inoculating loop or swab and then streaked out over the surface in one of several patterns.
STREAK PLATE
use of atmospheric or gaseous N for cell synthesis
Nitrogen fixation
CLASSES OF GROWTH FACTORS
Amino acids Purines/Pyrimidines Vitamins
What are the Macroelements?
Carbon Nitrogen Hydrogen Oxygen Sulfur Phosphorus
organisms that thrive at 40 – 85°C
THERMOPHILES