phases of bacterial growth, lag, log or exponential, stationary, and death phase.
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6 سال پیش
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Bacterial growth always follows a
Bacterial growth always follows a predictable pattern with four phases: Lag phase: very little to no bacterial growth. Log phase: the number of bacterial cells doubles at a constant, exponential rate. Stationary phase: population growth levels off as the rate of cell death equals the rate of cell division. Learn happily with Scientist Cindy at www.scientistcindy.com. Graphing Bacterial Growth
I mentioned that bacterial growth is not infinite and constant. In fact, bacterial growth is quite complex, influenced by any number of variables, including the species, temperature, pH, available nutrients, toxin concentrations, and competition between organisms. In order to illustrate what is happening during the life of your average bacteria, let's examine another infamous bacteria: Staphylococcus aureus. This common skin bacteria is often implicated in deadly bacterial infections. The reason I've chosen Staph. aureus is that under ideal conditions, it has a generation time of 30 minutes, a nice round time for performing calculations. A generation time is simply the time it takes for one cell to become two. So, if we start with one Staph. aureus cell, in 30 minutes there will be two. In another 30 minutes, there should be four, and so on to 8, 16, 32, 64, indefinitely. If we graphed this relationship, it would look like this, a perfect exponential graph.
Bacterial Growth Generation Time
Bacterial Graphing Growth
In reality, the graph of Staph. aureus growth will look like this. You can see a small portion that resembles the exponential graph, but before and after it looks a bit strange. Fortunately, we can break this graph into four sections, called phases. discrete colony
reproduction
nutrients: chemical and energy requirements
Autotrophs
Heterotrophs
Chemotrophs
Phototrophs
Obligate Aerobes
Obligate Anaerobes
Singlet Oxygen
Carotenoids
Superoxide free radicals
Peroxide Anion
Hydroxyl radical
Hydroxyl radical
Hydroxyl radical
Aerobes
Anaerobes
Facultative Anaerobes
Aerotolerant Anaerobes
Microaerophiles
Trace Elements
Growth Factors
Temperature, pH, Osmotic Pressure
psychrophiles
mesophiles
thermophiles
hyperthermophiles
why organisms are sensitive to changes in acidity
Neutrophiles
Acidophiles
alkalinophiles
why microbes require water
endospores and cysts
hypotonic solutions
hypertonic solutions
Crenation
obligate halophiles
facultative halophiles
Barophiles
Biofilms
Quorum Sensing
Inoculum
Medium
Environmental, Clinical, Stored
Culture
Pure Cultures
colony forming unit
Aseptic technique
Streak Plates
Pour Plates
reducing media
chemically Defined Media
Complex Media
Selective Media
Differential Media
enrichment culture
budding
refrigeration
deep-freezing
Lyophilization
Binary Fission
Generation time
Growth Curve
Lag phase
Log Phase
Stationary phase
Death Phase
Viable Plate Counts
Filtration
pH of bacteria
pH of molds and yeasts
plasmolysis
chemoheterotroph
chemoautotroph
phosphorus
sulfur
nitrogen
carbon
sterile
agar
capnophiles
biosafety level 1
biosafety level 2
biosafety level 3
biosafety level 4
colony
serial dilutions
spread plate method
turbidity
I mentioned that bacterial growth is not infinite and constant. In fact, bacterial growth is quite complex, influenced by any number of variables, including the species, temperature, pH, available nutrients, toxin concentrations, and competition between organisms. In order to illustrate what is happening during the life of your average bacteria, let's examine another infamous bacteria: Staphylococcus aureus. This common skin bacteria is often implicated in deadly bacterial infections. The reason I've chosen Staph. aureus is that under ideal conditions, it has a generation time of 30 minutes, a nice round time for performing calculations. A generation time is simply the time it takes for one cell to become two. So, if we start with one Staph. aureus cell, in 30 minutes there will be two. In another 30 minutes, there should be four, and so on to 8, 16, 32, 64, indefinitely. If we graphed this relationship, it would look like this, a perfect exponential graph.
Bacterial Growth Generation Time
Bacterial Graphing Growth
In reality, the graph of Staph. aureus growth will look like this. You can see a small portion that resembles the exponential graph, but before and after it looks a bit strange. Fortunately, we can break this graph into four sections, called phases. discrete colony
reproduction
nutrients: chemical and energy requirements
Autotrophs
Heterotrophs
Chemotrophs
Phototrophs
Obligate Aerobes
Obligate Anaerobes
Singlet Oxygen
Carotenoids
Superoxide free radicals
Peroxide Anion
Hydroxyl radical
Hydroxyl radical
Hydroxyl radical
Aerobes
Anaerobes
Facultative Anaerobes
Aerotolerant Anaerobes
Microaerophiles
Trace Elements
Growth Factors
Temperature, pH, Osmotic Pressure
psychrophiles
mesophiles
thermophiles
hyperthermophiles
why organisms are sensitive to changes in acidity
Neutrophiles
Acidophiles
alkalinophiles
why microbes require water
endospores and cysts
hypotonic solutions
hypertonic solutions
Crenation
obligate halophiles
facultative halophiles
Barophiles
Biofilms
Quorum Sensing
Inoculum
Medium
Environmental, Clinical, Stored
Culture
Pure Cultures
colony forming unit
Aseptic technique
Streak Plates
Pour Plates
reducing media
chemically Defined Media
Complex Media
Selective Media
Differential Media
enrichment culture
budding
refrigeration
deep-freezing
Lyophilization
Binary Fission
Generation time
Growth Curve
Lag phase
Log Phase
Stationary phase
Death Phase
Viable Plate Counts
Filtration
pH of bacteria
pH of molds and yeasts
plasmolysis
chemoheterotroph
chemoautotroph
phosphorus
sulfur
nitrogen
carbon
sterile
agar
capnophiles
biosafety level 1
biosafety level 2
biosafety level 3
biosafety level 4
colony
serial dilutions
spread plate method
turbidity
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در تاریخ 1397/08/02 منتشر شده
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