What is the Difference Between Protoplasts and Spheroplasts

The key difference between protoplasts and spheroplasts is that protoplasts are plant or microbial cells generated by stripping the cell wall completely, while spheroplasts are plant or microbial cells generated by stripping the cell wall partially.

A cell wall is a structural and defensive layer that surrounds some types of cells. It is located outer to the cell membrane. It can be tough, flexible, or rigid. The cell wall normally provides structural support and protection to the cells. Moreover, it can act as a filtering mechanism. Cell walls are absent in animal cells. But cell walls are present in other organisms such as algae, fungi, plants, and bacteria. Protoplasts and spheroplasts are two altered forms of plant or microbial cells from which the cell wall has been completely or partially removed.

CONTENTS

1. Overview and Key Difference
2. What are Protoplasts  
3. What are Spheroplasts
4. Similarities – Protoplasts and Spheroplasts
5. Protoplasts vs Spheroplasts in Tabular Form
6. Summary – Protoplasts vs Spheroplasts

What are Protoplasts?

Protoplasts are generated by stripping the cell wall from plant, bacterial or fungal cells through mechanical, chemical, or enzymatic means. Protoplast is a biological term that was coined by Hanstein for the first time in 1880. There are different enzymes that are available when isolating protoplast by enzymatic means. The cell walls are normally made up of a variety of polysaccharides. The protoplasts can be generated by degrading the cell walls with a mixture of appropriate polysaccharide degrading enzymes. Examples of some of these enzymes are cellulase, pectinase, xylanase (plant cells), lysozyme, N, O-diacetylmuramidase, lysostaphin (gram-positive bacteria), and chitinase (fungal cells). After the subsequent digestion of the cell wall, the protoplast becomes very sensitive to osmotic stress. Therefore, the cell wall digestion and protoplast storage must be performed in an isotonic solution to prevent rupture of the plasma membrane.

Furthermore, protoplasts are valuable research tools that can be used in a wide range of applications. The applications of protoplasts are a study of membrane biology, somaclonal variations in plant tissues, DNA transformation, plant breeding (hybrid tissue culture), and fluorescence-activated cell sorting (FACS).

What are Spheroplasts?

Spheroplasts are plant or microbial cells generated by stripping cell walls partially. Spheroplasts are usually made from bacterial cells such as gram-negative bacteria and fungal cells such as yeasts. Spheroplasts only retain a part of their cell wall. In the case of gram-negative bacterial spheroplasts, the peptidoglycan component of the cell wall has been removed, but the outer membrane component has not been removed. The method that is used to form spheroplast depends on the type of cell. Fungal cells can form after chitinase, lyticase or β glucuronidase treatment, whereas plant cells form spheroplasts after treatment with pectinase, cellulase, and xylanase. Moreover, bacterial spheroplasts are formed after treatment with antibiotics such as fosfomycin, vancomycin, moenomycin, lactivicin, and β-lactam antibiotics. Gram-negative bacteria can also be treated with lysozyme in the presence of EDTA to form spheroplasts.

The various applications of spheroplasts include the discovery of antibiotics that inhibit cell wall biosynthesis, studying the function of bacterial ion channels through a technique called patch clamping, transfection of animal cells, and facilitation of cell lysis.

What are the Similarities Between Protoplasts and Spheroplasts?

• Protoplasts and spheroplasts are two altered forms of plant or microbial cells from which the cell wall has been completely or partially removed.
• Both are spherical in shape.
• Both are extremely sensitive to osmotic and mechanical shock.
• The cell wall digestion and storage of both must be performed in an isotonic solution to prevent rupture of the plasma membrane.
• They are normally prepared in laboratory conditions.
• They have a wide range of applications.

What is the Difference Between Protoplasts and Spheroplasts?

Protoplasts are plant or microbial cells generated by stripping the cell wall completely, while spheroplasts are plant or microbial cells generated by stripping the cell wall partially. Thus, this is the key difference between protoplasts and spheroplasts. Furthermore, protoplasts are bounded by a single membrane, while spheroplasts are bounded by two membranes.

The below infographic presents the differences between protoplasts and spheroplasts in tabular form for side by side comparison.

Summary – Protoplasts vs Spheroplasts

Protoplasts and spheroplasts refer to altered forms of plant, bacterial or fungal cells. Protoplasts are plant or microbial cells generated by stripping the cell wall completely, while spheroplasts are plant or microbial cells generated by stripping the cell wall partially. So, this summarizes the difference between protoplasts and spheroplasts.

Reference:

1. “Protoplast.” An Overview | ScienceDirect Topics.
2. Simmons, Hannah. “What Are Spheroplasts?” News Medical Net.

Image Courtesy:

1. “Arabidopsis thaliana leaf protoplasts” By Martin von Rüden – Own work (CC BY 4.0) via Commons Wikimedia
2. “Penicillin spheroplast generation horizontal”  By Shudde – Own work (CC BY-SA 3.0) via Commons Wikimedia