PHENOTYPIC HETEROGENEITY OF THE PROGENY OF STREPTOMYCES-GRISEUS CONIDIA

In order to understand the complex ontogenetical processes, the develo pment of Streptomyces (S.) griseus was applied as a model. The develop mental cycle of S. griseus starts and ends as a conidium. In between, coenocytic mycelium develops which, if studied by cytomorphological of biochemical methods, exhibits conspicious heterogeneity. The hyphae d evelop into young, transient and old vegetative hyphae and different s tages of reproductive forms. In developmentally blocked mutants these sequences of events appear mixed in all possible associations. It seem s as if the program of development could be divided into several subpr ograms. The quantitative evaluation of the results show that the indiv idual morphological markers exhibit certain independence from each oth er realized with a given probability. The conidia of S. griseus are al so heterogeneous concerning all morphological and physiological traits examined so far (shape, size, light refraction, staining and shape of nucleoids with Feulgen, methyl green - pyronine, intensity and form o f polysaccharide distribution, heat resistance, etc.). Kinetics of the survival curves of two S. griseus strains - a well-sporulating and it s developmentally blocked nutant /24/ - are different from each other, one has many more heat resistant conidia than the other but the kinet ics of the survival curves of the two S. griseus strains indicate that spore populations of both react differently to heat treatment and hea t resistance can be modeled by assuming the presence of two independen t subpopulations of spores with different heat sensitivity. The emerge nce of two distinct subpopulations with (possibly) the same genetic ma ke-up is designated: phenotypic segregation. Heat resistance is first of all species specific (genetically determined) but the epigenetic se gregation seems to be characteristic of the developmental process. Thi s process can in certain mutants be affected by environmental conditio ns and more importantly by the so-called autoregulators (A-factor and factor C). Factor C and A-factor are needed to normal development, if their quantity or the time of addition to the culture was not optimal, the quantity of spares decreased.