In vitro spheroplast and L form induction within the pathogenic nocardiae

Six strains of Nocardia asteroides, two strains of N. caviae, and two strains of N. braziliensis were grown in medium supplemented with glycine, lysozyme, D cycloserine, glycine plus lysozyme, and glycine plus D cycloserine. It was shown that three strains of N. asteroides, and two strains of N. caviae, readily formed spheroplasts and/or protoplasts when grown in the presence of glycine plus either lysozyme of D cycloserine. This process was studied by both phase contrast microscopy and electron microscopy. The induced cultures were then plated on hypertonic medium for the isolation of L forms. It was shown that the organisms differed greatly in their ability to produce spheroplasts and subsequently grew as L forms or transitional phase variants.