Lesson 3.7. Bacterial Reproduction and Growth Kinetics

Binary Fission

MULTIPLICATION AND DIVISION CYCLE:

• Each individual will increase in size until it is large enough to divide into two identical daughter cells

• must be capable of growth and reproduction

• contains mRNA, rRNA, ribosomes, enzymes, cytoplasm, and at least one copy of the chromosome

DNA replication

MULTIPLICATION AND DIVISION CYCLE:

• chromosome segregation (Cphase) and cell division (D-phase), > 1 hr

Gram negative cells

MULTIPLICATION AND DIVISION CYCLE:

• divide by a process of constriction followed by membrane fusion

• 15 minutes

Gram positive cells

MULTIPLICATION AND DIVISION CYCLE:

• have a rigid cell wall, must develop a cross-wall that divides the cell into two equal halves

• 15 minutes

15-20 minutes

MULTIPLICATION AND DIVISION CYCLE:

• some organisms divide every _____________ under optimal conditions (not in nature)

Population growth

cell numbers will increase exponentially as a function of time

Generation time

time interval between one cell division and the next

N = No x 2^x

to get the cell population at xth generation, use:

colony

POPULATION GROWTH ON SOLID SURFACES:

a._____ – visible to the naked eye

b.if species of bacteria is spread on the surface of the agar media, each individual cell will produce a __________________; counted to estimate of the original number of cells

c.different species will produce colonies of ______________________, in color, size, shape and texture – useful diagnostic aid to identification

a = ?

single visible colony

POPULATION GROWTH ON SOLID SURFACES:

a._____ – visible to the naked eye

b.if species of bacteria is spread on the surface of the agar media, each individual cell will produce a __________________; counted to estimate of the original number of cells

c.different species will produce colonies of ______________________, in color, size, shape and texture – useful diagnostic aid to identification

b = ?

slightly different appearance

POPULATION GROWTH ON SOLID SURFACES:

a._____ – visible to the naked eye

b.if species of bacteria is spread on the surface of the agar media, each individual cell will produce a __________________; counted to estimate of the original number of cells

c.different species will produce colonies of ______________________, in color, size, shape and texture – useful diagnostic aid to identification

c = ?

Population Growth on Liquids

nutrients are equally available to all cells

Closed System

POPULATION GROWTH ON LIQUIDS:

• all available nutrients are present at the beginning of growth and waste products of metabolism are retained

inadequately preserved

EXAMPLE OF POPULATION GROWTH ON LIQUIDS (CLOSED SYSTEM):

a.__________________ pharmaceutical products

b.in ________________ tanks

c.____________ fermentations

a = ?

water storage

EXAMPLE OF POPULATION GROWTH ON LIQUIDS (CLOSED SYSTEM):

a.__________________ pharmaceutical products

b.in ________________ tanks

c.____________ fermentations

b = ?

industrial

EXAMPLE OF POPULATION GROWTH ON LIQUIDS (CLOSED SYSTEM):

a.__________________ pharmaceutical products

b.in ________________ tanks

c.____________ fermentations

c = ?

lag period

PARTS OF A CLOSED SYSTEM:

• the cells adapts its physiology to that required for growth on the available nutrients

logarithmic (log) phase

PARTS OF A CLOSED SYSTEM:

• cells increase exponentially, generation or doubling time may be calculated from the slope of the line

• includes primary metabolism which is breaking down carbon sources like glucose and generating organic acids (lactic acid)

stationary phase

PARTS OF A CLOSED SYSTEM:

• nutrients are consumed, and waste materials accumulate, growth rate is reduced towards an eventual stop

• undergoing secondary metabolic reactions in which organic acids are further modified into a wide range of metabolites like antibiotics

decline phase

PARTS OF A CLOSED SYSTEM:

• starvation will eventually lead to the death of some cells and adaptation to a dormant state of some cells

Open System

POPULATION GROWTH ON LIQUIDS:

• have a continual supply of fresh nutrients and removal of waste products

• growth rate is governed by the rate of supply of nutrients and the population size

bacteria in GIT receive a continuous supply of food and excess bacteria are voided with the feces

examples of an Open System on Liquids

bulk fluid phase

If the Open System is on a biofilm, extract nutrients from the _________________

Transformation

GENETIC EXCHANGE:

• ability of certain types of bacteria to absorb small pieces of naked DNA from the environment that may recombine into the recipient chromosome

Transduction

GENETIC EXCHANGE:

• transfer of DNA through bacteriophages, viruses that only infects bacteria

viral DNA

TRANSDUCTION PROCESS:

1. Injects _____________ into the host cell; in exceptional circumstances, it becomes incorporated (by recombination) into the chromosome of the bacterium

2. The viral DNA forms part of the __________________ and will be copied to all the daughter cells.

3. ________ of the viral DNA may become inaccurate, and may carry additional DNA of bacterial origin

4. _____________ from these virions will result in this bacterial DNA having moved between cells

1 = ?

bacterial chromosome

TRANSDUCTION PROCESS:

1. Injects _____________ into the host cell; in exceptional circumstances, it becomes incorporated (by recombination) into the chromosome of the bacterium

2. The viral DNA forms part of the __________________ and will be copied to all the daughter cells.

3. ________ of the viral DNA may become inaccurate, and may carry additional DNA of bacterial origin

4. _____________ from these virions will result in this bacterial DNA having moved between cells

2 = ?

Excision

TRANSDUCTION PROCESS:

1. Injects _____________ into the host cell; in exceptional circumstances, it becomes incorporated (by recombination) into the chromosome of the bacterium

2. The viral DNA forms part of the __________________ and will be copied to all the daughter cells.

3. ________ of the viral DNA may become inaccurate, and may carry additional DNA of bacterial origin

4. _____________ from these virions will result in this bacterial DNA having moved between cells

3 = ?

Subsequent infections

TRANSDUCTION PROCESS:

1. Injects _____________ into the host cell; in exceptional circumstances, it becomes incorporated (by recombination) into the chromosome of the bacterium

2. The viral DNA forms part of the __________________ and will be copied to all the daughter cells.

3. ________ of the viral DNA may become inaccurate, and may carry additional DNA of bacterial origin

4. _____________ from these virions will result in this bacterial DNA having moved between cells

4 = ?

Conjugation

GENETIC EXCHANGE:

• transfer a copy of plasmid DNA to a recipient cell through a hollow appendage called an F-pilus (sex pili)

• Transcribed at the cell membrane from the simplest form of plasmids - the Fertility factor (F-factor)

• Cells containing an F-factor are designated F+

F-factor

May be unassociated (F+) or integrated (Hfr or high frequency recombination)

integrated form of F-factor

can transfer a partial or complete copy of the donor chromosome that may be incorporated into the recipient chromosome

rapidly

In conjugation, if the transported DNA encoded a mechanism of antibiotic resistance it would not be difficult to imagine how whole populations could _______ acquire the resistance characteristics