Breaking up of Vegetative Mycelium of Nocardia and Streptomyces Cultures on Agar Film

Abstract

Cultures of Nocardia and Streptomyces were grown on agar film on glass slides and the mode of breaking up of their vegetative mycelium was studied. It was found that they broke into shorter filaments by two modes: fragmentation and autolysis. There were two types of fragmentation: one is when the divided cells are separated by empty splits and the other is when the cells are not separated but connected to each other, no splits thus being formed. When autolysis occurred at small intervals along the hyphae and then the intervening cytoplasm disappeared, the interstices appeared as empty splits which could not be distinguished from those caused by fragmentation. With the progress of autolysis, parts of the vegetative mycelia became ghost-like or beaded, which parts usually remained for a long time in Streptomyces cultures but tended to disappear in Nocardia isolates. The splits which had been caused by fragmentation or by autolysis were sometimes filled with newly developed filaments. Although both fragmentation and autolysis were found in Streptomyces as well as Nocardia, the former was more abundantly observed in Nocardia and the latter was predominant in Streptomyces.