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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 370318
Title Dormant ascospores of Talaromyces macrosporus are activated to germinate after treatment with ultra high pressure
Author(s) Dijksterhuis, G.B.; Teunissen, P.G.M.
Source Journal of Applied Microbiology 96 (2004)1. - ISSN 1364-5072 - p. 162 - 169.
Department(s) AFSG Food Quality
Publication type Refereed Article in a scientific journal
Publication year 2004
Keyword(s) byssochlamys-nivea ascospores - bacillus-subtilis spores - heat-resistance - phycomyces-blakesleeanus - hydrostatic-pressure - neosartorya-fischeri - flavus - inactivation - fulva
Abstract Aims: Ascospores of Talaromyces macrosporus are constitutively dormant and germinate after a strong external shock, classically a heat treatment. This fungus is used as a model system to study heat resistance leading to food spoilage after pasteurization. This study evaluates the effect of high pressure on the germination behaviour of these spores. Methods and Results: Ascospore containing bags were subjected to ultra high pressure and spores were plated out on agar surfaces. Untreated suspensions showed invariably very low germination. Increased germination of ascospores occurred after short treatments at very high pressure (between 400 and 800 MPa). Activation is partial compared with heat activation and did not exceed 6·9% (65 times that of untreated suspensions) of the spore population. Maximum activation was attained shortly (10 s¿3 min) after the pressure was applied and accompanied by cell wall deformations as judged by scanning electron microscopy. The spores observed in this study were harvested from cultures that were 39¿58 days old. The maturity of spores at similar developmental stages was measured by assessing the heat resistance of ascospores. Between 20 and 40 days heat resistance increased 2·4-fold, but only an additional increase of 1·3-fold was observed at later stages (40¿67 days). Conclusions: Our investigations show that high pressure constitutes a second type of shock that can activate heat-resistant ascospores to germinate. Activation is maximal after very short treatments and accompanied with changes in the cell wall structure. High-pressure activation is not the result of immaturity of the ascospores. Significance and Impact of the Study:These observations are relevant for the application of high pressure as a novel pasteurization method.
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