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Journal of Clinical Microbiology, February 2001, p. 478-484, Vol. 39, No. 2
Department of Medical Microbiology,
University Medical Center Nijmegen,1 and
Department of Medical Microbiology, Canisius Wilhelmina
Hospital,2 Nijmegen, The Netherlands
Received 14 August 2000/Returned for modification 21 September
2000/Accepted 31 October 2000
A microbroth kinetic model based on turbidity measurements was
developed in order to analyze the growth characteristics of three
species of filamentous fungi (Rhizopus microsporus, Aspergillus fumigatus, and Scedosporium prolificans)
characterized by different growth rates in five nutrient media
(antibiotic medium 3, yeast nitrogen base medium, Sabouraud broth, RPMI
1640 alone, and RPMI 1640 with 2% glucose). In general, five distinct
phases in the growth of filamentous fungi could be distinguished,
namely, the lag phase, the first transition period, the log phase, the
second transition period, and the stationary phase. The growth curves were smooth and were characterized by the presence of long transition periods. Among the different growth phases distinguished, the smallest
variability in growth rates among the strains of each species was found
during the log phase in all nutrient media. The different growth phases
of filamentous fungi were barely distinguishable in RPMI 1640, in which
the poorest growth was observed for all fungi even when the medium was
supplemented with 2% glucose. R. microsporus and A. fumigatus grew better in Sabouraud and yeast nitrogen base medium
than in RPMI 1640, with growth rates three to four times higher. None
of the media provided optimal growth of S. prolificans. The
germination of Rhizopus spores and Aspergillus and Scedosporium conidia commenced after 2 and 5 h of
incubation, respectively. The elongation rates ranged from 39.6 to
26.7, 25.4 to 20.2, and 16.9 to 9.9 µm/h for Rhizopus,
Aspergillus, and Scedoporium hyphae, respectively.
The germination of conidia and spores and the elongation rates of
hyphae were enhanced in antibiotic medium 3 and delayed in yeast
nitrogen base medium. In conclusion, the growth curves provide a useful
tool to gain insight into the growth characteristics of filamentous
fungi in different nutrient media and may help to optimize the
methodology for antifungal susceptibility testing.
0095-1137/01/$04.00+0 DOI: 10.1128/JCM.39.2.478-484.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Analysis of Growth Characteristics of Filamentous
Fungi in Different Nutrient Media
*
Corresponding author. Mailing address: Department of
Medical Microbiology, University Medical Center Nijmegen, P.O. Box
9101, 6500 HB Nijmegen, The Netherlands. Phone: 31-24-3614369. Fax: 31-24-3540216. E-mail: p.verweij{at}mmb.azn.nl.
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