Agar Lab Report
Agar
What is it and where is it from?
Derived from the cell walls of red algae, agar is a gelatinous substance extracted through a process of boiling and filtration. Agar is specifically used in laboratories for diagnostics and experimental purposes. Agars main purpose is to act as a growth medium for micro-organisms such as bacteria and fungi. The micro-organisms feed off the nutrients contained in Agar and can be both cultured and observed within it by scientists and the use of a microscope.
Using Agar
A drop, equivalent to10ml, of the substance being tested needs to be placed and spread over the Agars surface using a non-absorbent sterile tool (a teaspoon can suffice however a glass rod is preferable). It is important that the experiment …show more content…
I.e. if the pipet gives 10ml and 10 colonies are visible then 10ml x 10 colonies would give you the estimated number of bacteria per millilitre.
Taking into account that different bacteria counts can be resultant of two of the same bacterial experiments one can work out the amount of bacteria per ml of the original tested source in a more accurate way.
A rough estimate of the expected variation (variance) can be achieved by square rooting the number of counted colonies. I.e. if 100 colonies are counted one would do the following √(100 ) which is equivalent to 10.
One then takes the colony count number and plusses or minuses the answer to obtain a likely range of the true bacterial count per drop of the original source. I.e. 100- 10= 90 and 100+10=110 therefore the likely range is 110 to 90.
The likely range is then multiplied by the number of drops per ml of the amount of sample liquid placed on the Agar at the experiments beginning to give you the range of bacteria per ml of the original source. I.e. 110-90 x 20 (drops needed to obtain 1 ml from the pipet originally used) would give you 1800-2200 as the final calculation of how much bacteria there is per ml of the original tested
What is it and where is it from?
Derived from the cell walls of red algae, agar is a gelatinous substance extracted through a process of boiling and filtration. Agar is specifically used in laboratories for diagnostics and experimental purposes. Agars main purpose is to act as a growth medium for micro-organisms such as bacteria and fungi. The micro-organisms feed off the nutrients contained in Agar and can be both cultured and observed within it by scientists and the use of a microscope.
Using Agar
A drop, equivalent to10ml, of the substance being tested needs to be placed and spread over the Agars surface using a non-absorbent sterile tool (a teaspoon can suffice however a glass rod is preferable). It is important that the experiment …show more content…
I.e. if the pipet gives 10ml and 10 colonies are visible then 10ml x 10 colonies would give you the estimated number of bacteria per millilitre.
Taking into account that different bacteria counts can be resultant of two of the same bacterial experiments one can work out the amount of bacteria per ml of the original tested source in a more accurate way.
A rough estimate of the expected variation (variance) can be achieved by square rooting the number of counted colonies. I.e. if 100 colonies are counted one would do the following √(100 ) which is equivalent to 10.
One then takes the colony count number and plusses or minuses the answer to obtain a likely range of the true bacterial count per drop of the original source. I.e. 100- 10= 90 and 100+10=110 therefore the likely range is 110 to 90.
The likely range is then multiplied by the number of drops per ml of the amount of sample liquid placed on the Agar at the experiments beginning to give you the range of bacteria per ml of the original source. I.e. 110-90 x 20 (drops needed to obtain 1 ml from the pipet originally used) would give you 1800-2200 as the final calculation of how much bacteria there is per ml of the original tested