Spheroplast

A cell whose wall has been removed or substantially weakened while some membrane or wall material remains around it. Spheroplasts are osmotically fragile and are used to study membranes, wall synthesis, and cell transformation.

Peptidoglycan: A mesh-like polymer that forms the load-bearing cell wall of most bacteria. Enzymes or chemicals that remove this bacterial wall material can produce spheroplasts.
Bacterial transformation: The uptake and incorporation of extracellular DNA by bacterial cells. Wall removal can facilitate DNA entry into some bacteria during laboratory transformation.
Gram-negative bacteria: Bacteria with a thin peptidoglycan layer between inner and outer membranes. Their multiple envelope layers make the term spheroplast especially relevant.
Escherichia coli: A rod-shaped bacterium commonly found in the intestines of humans and other animals. Its outer membrane and peptidoglycan make it a standard model for bacterial spheroplast preparation.
Lysozyme: An enzyme that cleaves bonds in peptidoglycan and other bacterial cell-wall carbohydrates. It can digest peptidoglycan to generate wall-deficient cells under suitable conditions.
Protoplast fusion: The joining of wall-free plant or microbial cells to combine their contents and genetic material. Spheroplast-like cells can be fused to bring distinct cellular contents together.
Gram-positive bacteria: Bacteria with thick peptidoglycan walls and no outer membrane. Wall removal in these cells differs from spheroplast formation in Gram-negative bacteria.
Saccharomyces cerevisiae: A budding yeast species used in baking, brewing, and biological research. Enzymatic removal of its glucan-rich wall can create yeast spheroplasts.
Osmotic pressure: The pressure associated with differences in solute concentration across a selectively permeable membrane. Osmotic support limits water-driven swelling and rupture of the fragile cell.
Periplasm: The compartment between the inner and outer membranes of Gram-negative bacteria. Removing the outer wall layers helps expose or release periplasmic contents.

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