MOLECULAR PHYLOGENETIC, MORPHOLOGICAL, AND MYCOTOXIN DATA SUPPORT REIDENTIFICATION OF THE QUORN MYCOPROTEIN FUNGUS AS FUSARIUM-VENENATUM

Molecular phylogenetic, morphological, and mycotoxin data were obtaine d in order to investigate the relationships and identity of the Quorn mycoprotein fungus within Fusarium and to examine Quorn strains and co mmercial Quorn food products for trichothecene mycotoxins, Phylogeneti c analyses of aligned DNA sequences obtained via the polymerase chain reaction from the nuclear 28S ribosomal DNA, nuclear ribosomal interna l transcribed spacer region, and beta-tubulin gene exons and introns i ndicate that the Quorn fungus is Fusarium venenatum, rather than F. gr aminearum as previously reported. All of the Quorn strains examined we re morphologically degenerate aconidial colonial mutants except for NR RL 25139, which produced chlamydospores in recurved terminal chains to gether with mostly 5-septate sporodochial conidia on doliform monophia lides diagnostic of F. venenatum. Bootstrap and decay analyses provide strong support for a monophyletic lineage containing F. venenatum and several other type A trichothecene-producing species, while reference strains of F. guaminearum were nested in a separate clade of species that produce type B trichothecenes and/or zearalenone, Analysis of myc otoxins from rice cultures inoculated with Quorn strain NRRL 25416 rev ealed that four type A trichothecenes are produced, but at low levels relative to strain NRRL 22198 of F. venenatum. No trichothecene mycoto xins, however, were detected from the analysis of three commercial Quo rn products marketed for human consumption in England. (C) 1998 Academ ic Press.