Sexual reproduction as the cause of heat resistance in the food spoilage fungus Byssochlamys spectabilis (anamorph Paecilomyces variotii).
Appl Environ Microbiol, 2008/3;74(5):1613-9.
Houbraken J[1], Varga J, Rico-Munoz E, Johnson S, Samson RA
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PMID: 18192427DOI: 10.1128/AEM.01761-07
Impact factor: 5.005
Abstract
Paecilomyces variotii is a common cosmopolitan species that is able to spoil various food- and feedstuffs and is frequently encountered in heat-treated products. However, isolates from heat-treated products rarely form ascospores. In this study we examined by using molecular techniques and mating tests whether this species can undergo a sexual cycle and form ascospores. The population structure of this species was examined by analyzing the nuclear ribosomal internal transcribed spacer 1 (ITS1) and ITS2 and the 5.8S rRNA gene, as well as partial beta-tubulin, actin, and calmodulin gene sequences. Phylogenetic analyses revealed that P. variotii is a highly variable species. Partition homogeneity tests revealed that P. variotii has a recombining population structure. In addition to sequence analyses, mating experiments indicated that P. variotii is able to form ascomata and ascospores in culture in a heterothallic manner. The distribution of MAT1-1 and MAT1-2 genes showed a 1:1 ratio in the progeny of the mating experiments. From the sequence analyses and mating data we conclude that P. variotii is the anamorph of Talaromyces spectabilis and that it has a biallelic heterothallic mating system. Since Paecilomyces sensu stricto anamorphs group within Byssochlamys, a new combination Byssochlamys spectabilis is proposed.
MeSH terms
Actins; Adaptation, Physiological; Base Sequence; Calmodulin; Cluster Analysis; Crosses, Genetic; DNA Primers; DNA, Ribosomal Spacer; Food Microbiology; Genetics, Population; Hot Temperature; Molecular Sequence Data; Paecilomyces; Phylogeny; RNA, Ribosomal, 5.8S; Reproduction; Sequence Analysis, DNA; Spores, Fungal; Tubulin
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