A Kinetic Study of the Growth of Aspergillus nidulans and Other Fungi

Abstract

The growth kinetics of Aspergillus nidulans, Mucor hiemalis and Penicillium chrysogenum on solid media and in submerged culture were studied. Growth of A. nidulans colonies on solid medium can be divided into the four phases of lag, exponential, deceleration and constant growth rate. The growth kinetics of A. nidulans in submerged culture were similar to those commonly found for unicellular micro-organisms. The effects on colony radial growth rate, of glucose concentration, medium depth, oxygen partial pressure and temperature were studied. The radial growth rate of glucose-limited colonies of A. nidulans increased linearly with the log. of the initial glucose concentration. The effects of glucose concentration on internode length, hyphal density and hyphal diameter were also studied. At glucose concentrations above I % (wlv) there was an inverse relation between the radial growth rate of A. nidulans colonies and their peripheral hyphal density. The relations between colony radial growth rate (K,) and germ tube specific growth rate (ag) on solid media and specific growth rate in submerged culture (a,) were investigated. Direct proportionality between K, and a, of A. niduZans was found by varying specific growth rate by temperature changes. The germ tubes of A. nidulans conidia grew exponentially at a rate which was about 2.3 times as great as the specific growth rate of the organism in submerged culture. The colony radial growth rates of the three moulds could not be used as a measure of their relative specific growth rates in submerged culture.

A Kinetic Study of the Colony Growth of Streptomyces coelicolor A3(2) and J802 on Solid Medium

“…This results from the ability of filamentous fungi to control the rate of branch initiation, in response to variation in environmental conditions, permitting maintenance of maximum rates of hyphal extension, and therefore colony radial growth rate, while optimizing utilization of substrate behind the colony margin. For example, branching at the margin of colonies of Aspergillus nidulans increases with medium depth although colony radial growth rate is unaffected, while increased glucose concentration results in increases in both branching and rate of colony expansion (Trinci, 1969). Similar effects have also been reported for Geotrichum candidurn by Robinson & Smith (1979).…”

“…However, their colony radial growth rate is typically independent of medium depth while the effect of glucose concentration is less well defined and varies between species (Trinci, 1969). This results from the ability of filamentous fungi to control the rate of branch initiation, in response to variation in environmental conditions, permitting maintenance of maximum rates of hyphal extension, and therefore colony radial growth rate, while optimizing utilization of substrate behind the colony margin.…”

“…Unicellular organisms are generally not capable of such control and typically form discrete colonies whose size is limited by substrate diffusion into a peripheral growth zone of high biomass density. In addition, a threshold glucose concentration appears necessary for bacterial colony growth (Pirt, 1967) but not for fungi, which are capable of growing at extremely low glucose concentrations (Trinci, 1969).…”

Macromolecular Composition and Nuclear Division During Spore Germination in Aspergillus nidulans

“…of liquid DAN medium containing 50 pg./l. biotin (Trinci, 1969) (Manners, 1966). Some clumping occurred and separation was achieved by agitation of the suspensions with a finely drawn Pasteur pipette.…”

Productivity of Potato (Solanum tuberosum L.) as Influenced by Calcium Metalosate

“…Generally, soils contain 10 5 to 10 6 cfu/g and 100 to 1500 g biomass per meter square. Some of the fungi have the ability to make rapid growth on organic substrates in dry, acid, coarse textured soil and thus to reach nutrients available to unicellular microorganisms by diffusion (Trinci, 1969;Ambikapathy et al, 1994).…”