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Many species of fungi have been detected in the healthy human gut; however, nearly half of all taxa reported have only been found in one sample or one study. Fungi capable of growing in and colonizing the gut are limited to a small number of species, mostlyCandidayeasts and yeasts in the family Dipodascaceae (Galactomyces, Geotrichum, Saprochaete).Malasseziaand the filamentous fungusCladosporiumare potential colonizers; more work is needed to clarify their role. Other commonly-detected fungi come from the diet or environment but either cannot or do not colonize (PenicilliumandDebaryomycesspecies, which are common on fermented foods but cannot grow at human body temperature), while still others have dietary or environmental sources (Saccharomyces cerevisiae, a fermentation agent and sometime probiotic;Aspergillusspecies, ubiquitous molds) yet are likely to impact gut ecology. The gut mycobiome appears less stable than the bacterial microbiome, and is likely subject to environmental factors. [ABSTRACT FROM PUBLISHER]

This experiment exposed 3rd and 4th y undergraduates and graduate students taking a course in advanced food analysis to DNA extraction, polymerase chain reaction (PCR), and DNA sequence analysis. Students provided their own fish sample, purchased from local grocery stores, and the class as a whole extracted DNA, which was then subjected to PCR, gel electrophoresis, and Sanger sequencing. Students retrieved their sequences and identified their fish using the NCBI BLAST nucleotide database. Slightly more than half of the samples yielded sequences identical or close to expected (based on the identification of the fish on the packaging); some other samples matched unanticipated fish or other organisms, due to an incomplete database, minor sequencing errors, or laboratory contamination (human and fungal sequences); 1 canned tuna sample identified as hake could represent food fraud. [ABSTRACT FROM AUTHOR]

The biosynthetic pathway for amanitins and related cyclic peptides in deadly Amanita (Amanitaceae) mushrooms represents the first known ribosomal cyclic peptide pathway in the Fungi. Amanitins are found outside of the genus in distantly related agarics Galerina (Strophariaceae) and Lepiota (Agaricaceae). A long-standing question in the field persists: why is this pathway present in these phylogenetically disjunct agarics? Two deadly mushrooms, A. pallidorosea and A. subjunquillea, were deep sequenced, and sequences of biosynthetic genes encoding MSDINs (cyclic peptide precursor) and prolyl oligopeptidases (POPA and POPB) were obtained. The two Amanita species yielded 29 and 18 MSDINs, respectively. In addition, two MSDIN sequences were cloned from L. brunneoincarnata basidiomes. The toxin MSDIN genes encoding amatoxins or phallotoxins from the three genera were compared, and a phylogenetic tree constructed. Prolyl oligopeptidase B (POPB), a key enzyme in the biosynthetic pathway, was used in phylogenetic reconstruction to infer the evolutionary history of the genes. Phylogenies of POPB and POPA based on both coding and amino acid sequences showed very different results: while POPA genes clearly reflected the phylogeny of the host species, POPB did not; strikingly, it formed a well-supported monophyletic clade, despite that the species belong to different genera in disjunct families. POPA, a known house-keeping gene, was shown to be restricted in a branch containing only Amanita species and the phylogeny resembled that of those Amanita species. Phylogenetic analyses of MSDIN and POPB genes showed tight coordination and disjunct distribution. A POPB gene tree was compared with a corresponding species tree, and distances and substitution rates were compared. The result suggested POPB genes have significant smaller distances and rates than the house-keeping rpb2, discounting massive gene loss. Under this assumption, the incongruency between the gene tree and species tree was shown with strong support. Additionally, k-mer analyses consistently cluster Galerina and Amanita POPB genes, while Lepiota POPB is distinct. Our result suggests that horizontal gene transfer (HGT), at least between Amanita and Galerina, was involved in the acquisition of POPB genes, which may shed light on the evolution of the α-amanitin biosynthetic pathway. [ABSTRACT FROM AUTHOR]

Maize ( Zea mays) is a staple in many developing countries but is known to be prone to pest (insects, birds, and rodents) and fungal infestation. In Guatemala, mycotoxin contamination of cultivated products may occur owing to such factors as environmental conditions and the use of traditional agriculture operations. To assess the current maize conditions in Guatemala, a small-scale study was performed. Mold and insect counts and mycotoxin (aflatoxin and fumonisin) concentrations were determined on 25 farms in two townships (Chiantla and Todos Santos) of the Huehuetenango Department. Total fungal counts were 3.6 to 6.83 log CFU/g with no significant differences ( P > 0.05) across farms at different altitudes. Farms where maize was not produced but was purchased were at higher risk of fumonisin contamination, whereas local producers were mostly affected by aflatoxins. Aflatoxin was present in maize from 100% of farms at 1.0 to 85.3 ppb, and fumonisin was detected on 52% of farms at 0.4 to 31.0 ppm. Average mycotoxin consumption amounts were above the recommended maximum intake for aflatoxin in both produced and purchased maize and above the provisional maximum tolerable daily intake for fumonisin in purchased maize. Estimated daily intake was 0.01 to 0.85 μg/kg of body weight per day for aflatoxin and 2.9 to 310.0 μg/kg of body weight per day for fumonisin. An entomological analysis revealed overall 32% prevalence of Ephestia kuehniella (flour moth), 16% prevalence of Sitophilus zeamais (maize weevil), and 8% prevalence of Tribolium sp. (flour beetle) on the analyzed farms. This study highlighted poor agricultural practices used in the highlands of Guatemala. Current practices should be revised for the production of maize that is safe for consumption by the population in this region. [ABSTRACT FROM AUTHOR]