Factors affecting the variability of a cholesterol-utilizing streptomycete

This thesis is an account of various factors which influence the observed variability of a cholesterol utilizing Streptomyces species. Preliminary studies were carried out to determine the feasibility of using mycelial fragments of the test organism as plating units and as inoculum. Two mutants were isolated using nitrosoquanidine as mutagenic agents. Genetic recombination between the two auxotrophs was demonstrated and confirmed. Further, it was shown that genetic recombination could be a factor in the variability of the test organism Streptomyces I4 pH8 #2 (w). Storage of spores and their subsequent use as inoculum or as plating units was shown to play a role in variability. Loss of the ability to utilize cholesterol on storage makes it advisable to use careful check procedures to assure the presence of this or any particular physiological trait. Growth on other carbon sources than cholesterol was demonstrated to affect the subsequent ability of the organism to utilize cholesterol.