Induction of resistance to novobiocin in the novobiocin-producing organism Streptomyces niveus

Constitution of the metabolic type of streptomycetes during the first hours of cultivation

Using the examples of biosynthesis of streptomycin, bialaphos, actinorhodin, oligoketides and autoregulators during the first hours of streptomycete cultivation, it is stressed that the external environment in cooperation with the internal metabolic abilities of the cell determines the metabolic type that would develop during the life cycle of the producing streptomycetes. If we accept that a certain metabolic type (from the point of view of the production of secondary metabolites) was determined already during the first hours of cultivation of the microorganisms, we must also admit that the availability of primary metabolites in the so-called production phase of growth (stationary phase, idiophase, etc.) is to a certain extent determined by the very early stages of strain development.

Expression of novobiocin resistance genes in the novobiocin-producing organism Streptomyces niveus

RNA isolated at intervals during fermentation from the novobiocin-producing wild-type strain of Streptomyces niveus and from a series of novobiocin-non-producing (Nov-) mutants was hybridized to DNA probes containing sequences which specify novobiocin resistance. The probes were made from inserts contained in the clones pGL101 and pGL103 which increase the level of novobiocin resistance of S. lividans transformants from 10 micrograms ml-1 to 50 micrograms ml-1 and 150 micrograms ml-1, respectively. No hybridization was detected with the pGL101 probe. The pGL103 probe hybridized to RNA extracted during the later stages of growth--a pattern corresponding to the transition from low to high level novobiocin resistance during growth of S. niveus wild-type cultures. Neither probe hybridized to RNA extracted from four Nov- mutants. These mutants showed variable levels of novobiocin resistance but none expressed the high wild-type levels. The authors conclude that expression of the DNA sequence in pGL103 is associated with high level novobiocin resistance.