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The Effect of Oxygen Tension in the Medium on the Morphology and Growth Kinetics of Aspergillus nidulans
Abstract
SUMMARY: In glucose-limited continuous-flow cultures of Aspergillus nidulans, the mean length of hyphal segments and the degree of branching were independent of the dissolved oxygen tension. However, at dissolved oxygen tensions below 18 mmHg a few large isodiametric cells were observed, and at oxygen tensions below 3.5 mmHg free conidia appeared in the medium (although differentiated conidiophores were not produced).
The critical oxygen tension for Aspergillus nidulans, cultured at 30° in air-saturated glucose-limited medium (dilution rate (D) = 0.05 h.−1), was 7 mmHg, which suggested that after growth at air saturation the mould could grow without adaptation at oxygen tensions in the medium as low as 7 mmHg. However, when the oxygen tension of air-saturated steady-state cultures of the mould was lowered to 30 mmHg, or from 30 mmHg to a lesser oxygen tension, a period of adaptation was necessary before the mould culture could again achieve steady-state growth. This adaptation to lower oxygen tensions involved an increased cellular oxidative capacity and a lowered critical oxygen tension for growth. This latter result was indicative of an increased synthesis of the terminal oxidase at low oxygen tensions in the medium.
- Accepted:
- Published Online:
© Society for General Microbiology 1971