pH oscillations and constant low pH delay the appearance of highly branched (colonial) mutants in chemostat cultures of the quorn® myco-protein fungus, Fusarium graminearum A3/5
✍ Scribed by Marilyn G. Wiebe; Geoffrey D. Robson; Stephen G. Oliver; Anthony P. J. Trinci
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 831 KB
- Volume
- 51
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
At pH 5.8, highly branched (colonial) mutants appear in glucose-limited chemostat cultures of Fusarium graminearum A3/5 after ca. 400 h (ca. 107 generations) of growth. The appearance of these mutants was delayed by u p to 144 h (45 generations) when the culture was switched at intervals of 120 h between pH 4.8 and 6.6. The concentration of cycloheximide-resistant macroconidia in the culture was used as an indicator of the periodic selection of advantageous mutants and it was found that, in chemostat populations subjected to pH oscillations, the interval (210 +. 20 h ) between peaks was nearly double that observed in chemostat populations cultured at constant pH (124 ? 12 h at constant pH 5.8 and 120 h ? 17 h at constant pH 4.51, indicating that the population evolved more slowly under oscillating pH than under constant pH. When grown in mixed culture with t h e parental strain (A3/5), the selective advantage of two colonial mutants isolated from chemostat cultures grown under conditions of oscillating pH was found to be pH dependent. Compared to cultures grown at constant pH 5.8, a delay of ca. 312 h (87 generations) in the appearance of colonial mutants was observed when F. graminearumA315 was grown in glucose-limited chemostat culture at constant pH 4.5.