DATE: 17/18/2022
EXPERIMENT NO: 1.2
SERIAL DILUTION AND SPREAD PLATE
AIM:
To isolated colonies of microorganisms from a mixed culture of organism and to
determine its CFU/ml…
PRINCIPLE:
Serial dilution is the stepwise dilution of a substance in solution. Usually the dilution
factor at each step is constant, resulting in a geometric progression of the concentration
in a logarithmic fashion. Serial dilution is used to reduce the concentration of
microscopic organisms or cells in a sample. So, by calculating the total dilution over the
entire series., it is possible to know how many bacteria started with. In natural habitats,
bacteria usually grow together in populations containing a number of species. In order
to adequately study and characterize an individual bacterial species, one needs a pure
culture. Spread plate technique is the method of isolation of microorganisms and its
enumeration in a mixed culture and distributing it evenly over the surface of a medium.
The technique makes it easier to quantify bacteria in a solution. In this technique a
small volume of dilutes bacterial mixture is transferred to the center of an agar plate
and evenly spread over the surface with a sterile L- shaped glass rod. The rod is
normally sterilized by dipping in alcohol and flame off. After incubation some of the
dispersed cells develop into isolated colonies. A colony is a large number of bacterial
cells on acid medium which is visible to the naked eye as a discrete entry. The plate
needs to be dried at room temperature, so that the agar can absorb the bacteria more
readily. By this procedure one assumes that a colony is derived from one cell and
therefore represents a clone of a pure culture. After incubation the general form of the
colony and the shape of the edge or margins can be determined by looking down at the
top of the colony. The number of microorganisms present in the particular test samples
is determine using the formula,
CFU/mL = Number of colonies* Dilution Factor/ volume of sample used
USES OF SPREAD PLATE TECHNIQUE
It is used for viable plate counts, in which the total number of colony forming
units, on a single plate is numerated.
It is used to calculate the concentration of cells in the tube from which the
sample was plated.
Spread plate is routinely used in enrichment solution and screening experiment.
EXPERIMENT NO: 1.2
SERIAL DILUTION AND SPREAD PLATE
AIM:
To isolated colonies of microorganisms from a mixed culture of organism and to
determine its CFU/ml…
PRINCIPLE:
Serial dilution is the stepwise dilution of a substance in solution. Usually the dilution
factor at each step is constant, resulting in a geometric progression of the concentration
in a logarithmic fashion. Serial dilution is used to reduce the concentration of
microscopic organisms or cells in a sample. So, by calculating the total dilution over the
entire series., it is possible to know how many bacteria started with. In natural habitats,
bacteria usually grow together in populations containing a number of species. In order
to adequately study and characterize an individual bacterial species, one needs a pure
culture. Spread plate technique is the method of isolation of microorganisms and its
enumeration in a mixed culture and distributing it evenly over the surface of a medium.
The technique makes it easier to quantify bacteria in a solution. In this technique a
small volume of dilutes bacterial mixture is transferred to the center of an agar plate
and evenly spread over the surface with a sterile L- shaped glass rod. The rod is
normally sterilized by dipping in alcohol and flame off. After incubation some of the
dispersed cells develop into isolated colonies. A colony is a large number of bacterial
cells on acid medium which is visible to the naked eye as a discrete entry. The plate
needs to be dried at room temperature, so that the agar can absorb the bacteria more
readily. By this procedure one assumes that a colony is derived from one cell and
therefore represents a clone of a pure culture. After incubation the general form of the
colony and the shape of the edge or margins can be determined by looking down at the
top of the colony. The number of microorganisms present in the particular test samples
is determine using the formula,
CFU/mL = Number of colonies* Dilution Factor/ volume of sample used
USES OF SPREAD PLATE TECHNIQUE
It is used for viable plate counts, in which the total number of colony forming
units, on a single plate is numerated.
It is used to calculate the concentration of cells in the tube from which the
sample was plated.
Spread plate is routinely used in enrichment solution and screening experiment.
