Total population count

Total population count is a method used to quantify the number of microorganisms present in a given sample.
This method covers all individuals irrespective of their physiological state, i.e. it counts both viable (alive and capable of reproducing) and non-viable (dead or incapable of reproducing) microorganisms.
It is an indirect method since it works by observing effects associated with the presence of microorganisms not individual organisms.

One of the methods of determining total count is turbidometry. This technique is based on measuring the cloudiness or turbidity of the solution caused by microbial cells.
- Advantage: It allows quick and simple assessment of microbial population.
- Disadvantage: It cannot differentiate between viable and non-viable organisms.
Another method of total cell count is dry weight measurements. It involves drying and weighing the collected microbial biomass.
- Advantage: It provides a total count of all microbes.
- Disadvantage: It cannot distinguish between different species or forms.
A direct microscope count is another solution. In this method, a known volume of a sample is observed under the microscope, and the number of organisms present is directly counted.
- Advantage: This technique doesn’t require microbial growth therefore the result can be obtained more quickly.
- Disadvantage: It cannot distinguish between viable and non-viable organisms.

The changes in the environment can influence the total population count. Factors such as temperature, pH, nutrition availability and oxygen levels can dramatically affect the number of organisms.
Furthermore, the sampling technique could also affect the total count. Improper techniques could lead to overestimation or underestimation of the microbial population.
The presence of microbial interactions like antagonism (one microbe inhibits others) or synergism (one microbe promotes the growth of others) significantly impacts the total population count.

The methods employed in total population count are fundamental in numerous areas ranging from water treatment plants to medical diagnostics.
It helps in understanding the pathogenic behaviour of harmful microbes and designing specific treatments in microbial diseases.
It aids the advancement of biotechnology industry by understanding the total microbial count to optimise reactions in industrial fermentations.
By quantifying microorganisms in different environments, it contributes to the development of environmental microbial ecology.