Biological control of mites by xerophileEurotiumspecies isolated from the surface of dry cured ham and dry beef cecina

摘要

Some meat dry products, including dry cured ham and dry beef cecina, are cured in cellars at moderately cold temperature allowing the growth of a lawn of fungi on their surface. During the curing process, frequently these products became contaminated with fungivore mites of the Acaridae family that feed on fungal mycelium and spores. Aims The aim of this article is to study the possible biological control of mites by fungi that form part of the normal microbiota of these meat products. Methods and Results Some yellow/orange pigmented fungi growing on the ham surface decreased the proliferation of mites; therefore, we isolated from ham and cecina xerophilic yellow/orange coloured fungal strains that were identified as members of the genusEurotium(recently reclassified asAspergillussectionAspergillus). Using molecular genetic tools, we have identified 158 strains asEurotium rubrum(Aspergillus ruber), Eurotium repens(Aspergillus pseudoglaucus) andEurotium chevalieri(Aspergillus chevalieri). Two strains,E. rubrumC47 andE. rubrumC49, showed strong miticidal activity. The toxic compound(s) are associated with the formation of cleistothecia. In synchronized mite development experiments, we observed that all stages of the mite lifecycle were inhibited by theE. rubrumC47 strain. In addition, we searched for miticidal activity in 13 culture collectionEurotiumstrains isolated from different habitats, and found that only one,Eurotium cristatumNRRL 4222 (Aspergillus cristatus) has a strong miticidal activity. Conclusions These fungal strains have proliferated on the surface of ham and cecina for decades, and possibly have acquired miticidal activity as a resistance mechanism against fungivores. Significance and Impact of the Study Biological control of infecting mites by favouring growth ofE. rubrunC47, in place of the normal mixed population ofAspergillusandPenicillium,is an attractive approach to control mite infestations.