Dynamics of spore germination and mycelial growth of streptomycetes under low humidity conditions

摘要

At extremely low values of moisture pressure (-96.4 MPa; a(w) 0.50), the spores of xerotolerant streptomycetes (Streptomyces odorifer and S. rubiginosohelvolus) germinated, their germ lengths increased, and lateral branching of the mycelium was observed after 5 days of incubation in a thin layer of agarized nutrient medium. At -22.6 MPa (a(w) 0.86), the mycelium begins to branch after a 2-day incubation; over a 5-day incubation at -2.8 MPa (a(w) 0.98), it goes through a reproduction cycle, which culminates in spore formation. The mathematical model approach enabled us to elucidate the behavioral patterns of Streptomyces spores in a thin layer of agarized nutrient medium at low humidity levels. The dynamics of spore germination is governed by the exponential law, which allows calculation of the average duration of the period a before spore germination, as well as the time needed for 50% of viable spores to germinate.