BACTERIAL GROWTH REQUIREMENT Flashcards
involves an orderly and organized increase in the sum of all components of the
organism which may entail replication of all cellular structures, organelles, and
components.
Growth
concerned with the increase in number of cells and not increase in the size of the organism
• Microbial growth
The process by which organisms divide and reproduce
BINARY FISSION
Time required for a cell to divide and its population to
double
GENERATION TIME
Illustrates the phases in the growth of the population of bacteria when they are grown in a culture of fixed volume. It reflects the different stages in the growth of a bacterium
BACTERIAL GROWTH CURVE
- Bacteria are still adjusting to their environment
• Bacteria absorb nutrients, synthesize enzymes, and prepare for cell division.
• Cells grow in size but not in number
LAG PHASE
*Exponential or logarithmic phase
• Rapid binary fission
• Number of cells grow exponentially
• Very susceptible to Gram Staining and cell wall inhibitors
LOG PHASE
- culture is at its greatest population density.
• Number of cells produced= number of cells dying
• nutrients in the liquid medium are used up
• concentration of toxic waste products from the metabolizing bacteria build up
STATIONARY PHASE
*aka logarithmic decline phase Accumulation of toxic metabolites and autolytic enzymes
• culture may die completely, or a few microorganisms or may continue to survive for months
• formation of spores
• Morphologic changes occur (Bacteria assume different shapes)
DEATH PHASE
give the BACTERIAL GROWTH REQUIREMENTS (physical)
- water/moisture
- Temperature
- pH
- Osmotic pressure
- Oxygen
why is water/moisture a physical requirement for bacterial growth?
The bacterial cell is composed mainly of water. All living organisms require water to carry out their normal metabolic processes, and most will die in environments containing too little moisture.
live in the refrigerator
(0-20 oC) Psychrophiles
very pathogenic
.Mesophiles (21-45 oC)
freeze at body temperature
Thermophiles (46 oC and higher)
bacterial physical requirement – pH 8.4 – 9.0
Alkalophiles
bac growth req– pH 6.5 – 7.5
Neutrophiles
Acidophiles
– pH less than 6
osmotic pressure- – require very high salt concentration for growth
.Extreme halophiles
OSMOTIC PRESSURE- require very high salt concentration for growth.
Extreme halophiles
require enough salt concentration for growth
Obligate halophiles
– do not require high salt concentration but able to grow at salt concentrations up to 2%.
Facultative halophiles
Only aerobic growth; oxygen required. high concentration of oxygen (bacteria all at the top)
OBLIGATE AEROBES
growth is best where most oxygen is present, but occurs throughout tube. Growth is greater in presence of oxygen
FACULTATIVE ANAEROBES
only anaerobic growth, ceases in presence of oxygen. growth where there is no oxygen
OBLIGATE ANAEROBES
Only anaerobic growth, continues in presence of oxygen, occurs evenly, oxygen has no effect
AEROTOLERANT ANAEROBES
only aerobic growth; oxygen required in low concentration, growth occurs where a low concentration of oxygen has diffused into medium (BACTERIA IN THE MIDDLE)
MICROAEROPHILES
A FACULTATICE ANAEROBE WITH NO CELL WALL
MYCOPLASMA
WHAT ARE THE CHEMICAL REQUIREMENTS?
- carbon
- nitrogen, sulfur, phosphorus
- inorganic ions
- growth factors
organisms that use lift as an energy source
PHOTOTROPHS
organisms that use chemicals as an energy source
CHEMOTROPHS
organisms that use CO2 as a carbon source
AUTOTROPHS
e.g., algae, plants, some photosynthetic bacteria including cyano bacteria
PHOTOAUTOTROPHS
e.g, some bacteria
CHEMOAUTOTROPHS
organisms that use organic compounds other than COc as a carbon source
HETEROTROPHS
e.g, some photosynthetic bacteria
PHOTOHETEROTROPHS
e.g, protozoa, fungi, animals, most bacteria
CHEMOHETEROTROPHS
necessary for synthesis of proteins and nucleic acids
Nitrogen, Sulfur, Phosphorus
what are the inorganic ions?
magnesium
potassium
calcium
iron
stabilizes ribosomes, cell membranes, and nucleic acids; also serves as co-factor in the activity of enzymes
MAGNESIUM (Mg)
for normal functioning and integrity of ribosomes and enzyme activities
POTASSIUM (K)
important component of gram-positive bacterial cell wall and contributes to the resistance of bacterial endospores
CALCIUM (Ca)
component of cytochrome, a component of the electron transport chain and co-factor for enzymatic activities
IRON (Fe)
Essential to promote the growth and development of the bacterial cell. These include Vitamin B Complex and amino acids.
Growth Factors
bacteria with the fastest generation time
BACILLUS THERMOPHILUS (1.3MINS)
Bacteria with the longest generation time
TREPONEMA PALLIDUM (1980mins)
