What is the Difference Between Viable and Nonviable Cells

The main difference between viable and nonviable cells is that viable cells can grow whereas nonviable cells are dead and are unable to grow. Furthermore, cryopreserved frozen cells are viable while snap-frozen cells are nonviable.

Viable and nonviable cells are two types of cells in the cell cultures. Identifying the difference between viable and nonviable cells can be done employing flow cytometry or various stains.

Key Areas Covered

1. What are Viable Cells
     – Definition, Cryopreserving, Plate Counting
2. What are Nonviable Cells
     – Definition, Facts, Flow Cytometric Counting
3. What are the Similarities Between Viable and Nonviable Cells
     – Outline of Common Features
4. What is the Difference Between Viable and Nonviable Cells
     – Comparison of Key Differences

Key Terms

Cryoprotectant, Flow Cytometric Counting, Nonviable Cells, Plate Counting, Viable Cells, Viable Stains

What are Viable Cells

Viable cells are the cells that can grow in a cell culture. Therefore, they are alive. However, it is necessary to freeze the cells to keep them for a long period in the laboratory. Here, DMSO (dimethylsulfoxide) is an essential ingredient in the medium. The main function of DMSO is to remove intracellular water from the cells slowly, protecting the shattering of the cell membrane from the formation of ice during chilling. Also, this protects the organelles from ice formation. Therefore, DMSO functions as a cryoprotectant that cryopreserves cells during freezing. Those frozen cells can be thawed later and placed in a growth media.

Figure 1: DMSO

Besides, plate counting is the widely employed method for viable cell counting; this identifies the number of actively-growing cells in a sample. Spread plate method and streak plate method are two methods in plate counting.

What are Nonviable Cells

Nonviable cells are the cells that cannot grow to produce colonies in a cell culture. But, the total number of cells include both viable and nonviable cells in a particular culture. Especially, those cells that have undergone snap-freezing (the process of rapid freezing of samples with dry ice) are not viable anymore as their cell membranes shatter in response to rapid freezing.

Figure 2: Urine Cultured on Oxoid Brilliance UTI Agar Plate
Patient Sample with Clinical Urinary Tract Infection (UTI) (Top), Mixed Culture (Bottom)

Stains are involved in the discrimination between viable and nonviable cells by flow cytometric methods. The types of stains that stain nonviable cells are Trypan blue, Nigrosin, and Erythrosin B. The cell membrane of the viable cells exclude these stains. However, stains enter the cytoplasm of both dead and damaged cells. Moreover, viable stains only stain the viable cells by entering the cells by cellular mechanisms. Methylene blue is a viable stain.

Similarities Between Viable and Nonviable Cells

• Viable and nonviable cells are two types of cells in cell cultures.
• Moreover, they are present in regular cell culture.
• Also, both flow cytometry and plate counting help to discriminate between the two types of cells.

Difference Between Viable and Nonviable Cells

Definition

Viable cells refer to live cells while nonviable cells refer to dead cells that are incapable of living, developing, or reproducing. Thus, this is the main difference between viable and nonviable cells.

Ability to Grow

Moreover, viable cells can grow while nonviable cells are unable to grow.

Live or Dead

While viable cells are alive, nonviable cells are dead.

Freezing

Another difference between viable and nonviable cells is that the cells frozen with cryoprotectants are viable while snap-frozen cells are nonviable.

Stains

Trypan blue, Nigrosin, and Erythrosin B stain nonviable cells while Methylene blue stains viable cells. Hence, this is another difference between viable and nonviable cells.

Conclusion

Viable cells are the cells that can grow in cell cultures while nonviable cells are unable to grow in cell culture. Moreover, it is possible to maintain the viability of the cells by freezing them along with DMSO. But, snap-freezing destroys the cell membrane. Therefore, the main difference between viable and nonviable cells is the ability to grow cells in cell culture.

Reference:

1. “Counting Bacteria|Boundless Microbiology.” Lumen Learning, Lumen, Available Here

Image Courtesy:

1. “Dimethylsulfoxid” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia  
2. “Urine cultured on Oxoid Brilliance UTI Agar plate” By Nathan Reading from Halesowen, UK – Urine Culture – Oxoid Brilliance U.T.I. Agar (CC BY 2.0) via Commons Wikimedia