Question

Discuss any three ways that can be employed to measure microbial cell growth.

Hint:

Make sure to remember that there are various ways to measure microbial growth, including both direct and indirect methods.

Answer 1

Viable Plate Count Method: This method enumerates viable cells in a microbial culture by counting colonies that develop on a petri dish. The resultant colony-forming units (CFUs) reflect the cellular concentration in the initial culture.
Turbidity Measurement: A spectrophotometer quantifies microbial culture turbidity or optical density. The absorbance at a specific wavelength correlates directly with cell concentration, offering a rapid estimation of cell density. 
Coulter Counter: This instrument directly counts cells as they traverse a narrow aperture, providing an immediate cell number reading, commonly employed for cell suspension quantification. 
Dry Weight: This technique determines biomass by measuring the mass of a fixed culture volume after desiccation. 
Wet Weight: This method involves direct measurement of the mass of a fixed culture volume in its hydrated state. 
ATP Measurement: Cellular ATP concentration in a culture is quantified via ATP bioluminescence assay.