Complex sentence: These strains are generated in the laboratory from species such as "Bacillus subtilis" that usually have cell walls by inhibiting peptidoglycan synthesis with antibiotics in a culture medium that is the same osmolarity as the bacterial cytosol, which prevents cell lysis by osmotic shock.
Split into simpler sentences: These strains are generated in the laboratory from species such as "Bacillus subtilis" (which usually have cell walls) by inhibiting peptidoglycan synthesis with antibiotics. This is done in a culture medium that is the same osmolarity as the bacterial cytosol, which prevents cell lysis by osmotic shock.