The preservative propionic acid differentially affects survival of conidia and germ tubes of feed spoilage fungi

Jan Dijksterhuis, Martin Meijer, Tineke van Doorn, Jos Houbraken, Paul Bruinenberg

Onderzoeksoutput: Bijdrage aan wetenschappelijk tijdschrift/periodieke uitgaveArtikelWetenschappelijkpeer review

Samenvatting

Propionic acid is widely used as a preservative in (poultry) feed. In this study we have isolated and identified fungal strains from nine samples poultry feed originating from different countries. The majority of the strains were Aspergilli with a eurotium-morph, such as Aspergillus proliferans and A. chevalieri. These and three other species were selected and tested for their sensitivity towards the feed preservative propionic acid, among them Penicillium lanosocoeruleum. The determined MIC values of 6.1-31 mM of these poultry feed specific fungi were well in the range as described in literature. Propionic acid (at 31 mM) damages conidia (spores) in a species dependent fashion after a 24-hour-treatment. The majority of the conidia (over 70%) of P. lanosocoeruleum germinated within 60 h on agar medium, while 50 and 80% of the A. chevalieri and A. proliferans conidia did not, respectively. Dependent on the species, cell damage was visible after incubation with propionic acid. Germ tubes of P. lanosocoeruleum in a biofilm showed extensive (85%) cell death after a 30 min treatment with propionic acid and slightly lower sensitivity was observed with A. proliferans (62% cell death). Microscopic analysis of these fungal biofilms revealed extensive damage to the cell membrane and showed distorted intracellular structures. Fluorescent life-dead staining of the germ tubes showed a clear dose response of propionic acid indicating a fungicidal effect on these growing cells. These results show that conidia can be inactivated by propionic acid, but that germ tubes show a much higher sensitivity. These observations shed new light on the mode of action of this important preservative to prevent fungal contamination of feed.

Originele taal-2Engels
Pagina's (van-tot)108258
TijdschriftInternational Journal of Food Microbiology
Volume306
DOI's
StatusGepubliceerd - 02 okt 2019

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