Protoplast & Spheroplast

Protoplast

Protoplast are generally defined as plasma membrane and everything within i.e. a cell without a cell wall is protoplast. They are generally derived from Gram positive bacteria. When Gram positive bacteria are incubated in an isotonic solution containing antibiotic penicillin, protoplast formation takes place. Penicillin basically inhibits the peptidoglycan synthesis and cell wall of Gram positive bacteria contains peptidoglycan mainly. So, it inhibits cell wall formation. Due to the absence of cell wall, protoplast are spherical in shape and are sensitive to osmotic stress. They are used for DNA transformation as presence of cell wall will interfere with the uptake of DNA into the cell.

Spheroplast 

Spheroplast are formed by the partial removal of the cell wall component. When Gram negative bacteria is treated with penicillin, they retain their outer membrane and forms spheroplast. They are spherical in shape and are osmotically sensitive.