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

Abstract

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.

Effect of light on germinating spores ofStreptomyces viridosporus

“…These results indicate that the light sensitive period occurs during the 22 to 28 first hours of incubation. According to microscopic examination, this period corresponds to the early state of germination, including germ tube emergence and linear hyphal growth described by Janecek et al [13]. Moreover when spores that had been pre‐germinated in the dark were spread on growth medium and incubated in the light, CFU counts obtained after 4 days were identical to those obtained from pre‐germinated spores incubated in the dark (data not shown).…”

Effect of light on germinating spores of Streptomyces viridosporus

“…These results indicate that the light sensitive period occurs during the 22 to 28 ¢rst hours of incubation. According to microscopic examination, this period corresponds to the early state of germination, including germ tube emergence and linear hyphal growth described by Janecek et al [13]. Moreover when spores that had been pre-germinated in the dark were spread on growth medium and incubated in the light, CFU counts obtained after 4 days were identical to those obtained from pregerminated spores incubated in the dark (data not shown).…”

Production of indole diterpenes by Aspergillus alliaceus

“…Although highly suitable for the growth phase, glucose is commonly an interfering carbon source in secondary metabolite synthesis; non-interfering carbon sources are glycerol, disaccharides (lactose, sucrose, maltose), monosaccharides (galactose, fructose), starch, citrate, and slowly fed or low glucose concentrations (Bu'lock, 1975;Janeček et al, 1997;Rhodes and Fletcher, 1966). It was the combination of rapidly and slowly metabolized carbon sources that proved beneficial to lovastatin synthesis (Hajjaj et al, 2001).…”

“…This nonreplicatory growth typically consists of the accumulation of reserve materials (i.e., mycelial insolubles such as polysaccharides and macromolecules) and can be up to 50-60% of dry cell weight at harvest (Aiba et al, 1965;Bu'lock, 1975;Martin and Demain, 1980). Primary metabolites have a significant effect on secondary metabolism owing to the fact that primary metabolism supplies the precursors of secondary metabolism; consequently factors which affect primary metabolism indirectly can affect secondary metabolism (Drew and Demain, 1977;Janeček et al, 1997). Specifically, primary metabolite formation is proportional to growth rate, and biomass concentration influences secondary metabolite formation (Bosnjak et al, 1990).…”

“…The selection of carbon and nitrogen sources in medium is important with respect to their concentration and type. A carbon-to-nitrogen ratio of 10:1 is considered optimum (Janeček et al, 1997), but this rule-of-thumb can be difficult to apply to fed-batch processes and media containing undefined nutrients. Specifically, the rate at which carbon sources are metabolized influences biomass formation and primary/secondary metabolite production (Stanbury and Whitaker, 1984).…”