Bacterial Foodborne Pathogens and Mycology Research Unit

Peoria, IL, United States

Bacterial Foodborne Pathogens and Mycology Research Unit

Peoria, IL, United States
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Ward T.J.,Bacterial Foodborne Pathogens and Mycology Research Unit | Usgaard T.,Bacterial Foodborne Pathogens and Mycology Research Unit | Evans P.,Food Safety and Inspection Service
Applied and Environmental Microbiology | Year: 2010

A 30-probe assay was developed for simultaneous classification of Listeria monocytogenes isolates by lineage(I to IV) major serogroup (4b1/2b1/2aand 1/2c) and epidemic clone (EC) type (ECI ECIa ECII and ECIII). The assay was designed to facilitate rapid strain characterization and the integration of subtype data into risk-based inspection programs. © 2010, American Society for Microbiology.

Hubka V.,Academy of Sciences of the Czech Republic | Hubka V.,Charles University | Kolarik M.,Charles University | Kubatova A.,Charles University | Peterson S.W.,Bacterial Foodborne Pathogens and Mycology Research Unit
Mycologia | Year: 2013

Aspergillus section Aspergillus contains economically important, xerophilic fungi that are widely distributed in nature and the human environment and are known for their ability to grow on substrates with low water activity. The taxa were revised based on sequence data from four loci, PCR fingerprinting, micro- and macromorphology, and physiology. The number of taxa was reduced to 17 species, all of which can be distinguished with sequence data from either the caM or RPB2 locus. The original description of A. proliferans was supplemented by a description of its teleomorph. This species seems to be relatively common and often has been confused with A. glaucus. In addition, green sporulating isolates of A. niveoglaucus isolated from food and several other substrates are indistinguishable in phenotype from A. glaucus. A dichotomous key based on ascospore size and ornamentation and the ability to grow at specific combinations of temperature and water activity is provided for identification of species. In response to recent changes in the botanical code, we transferred the Eurotium species to Aspergillus and selected one name for each species. © 2013 by The Mycological Society of America.

Naumann T.A.,Bacterial Foodborne Pathogens and Mycology Research Unit | Wicklow D.T.,Bacterial Foodborne Pathogens and Mycology Research Unit | Price N.P.,Renewable Product Technology Research Unit
Biochemical Journal | Year: 2014

Cmps (chitinase-modifying proteins) are fungal proteases that truncate plant class IV chitinases by cleaving near their Ntermini. We previously described Fv-cmp, a fungalysin protease that cleaves a conserved glycine-cysteine bond within the hevein domain. In the present paper we describe a new type of cmp, polyglycine hydrolases, as proteases that selectively cleave glycine-glycine peptide bonds within the polyglycine linker of plant class IV chitinases. Polyglycine hydrolases were purified from Cochliobolus carbonum (syn. Bipolaris zeicola; Bz-cmp) and Epicoccum sorghi (syn. Phoma sorghina; Es-cmp) and were shown to cleave three different maize class IV chitinase substrates. The proteolytic cleavage sites were assessed by SDS/PAGE and MALDI-TOF-MS and indicated the cleavage of multiple peptide bonds within the polyglycine linker regions. Site-directed mutagenesis was used to produce mutants of maize ChitB chitinase in which two serine residues in its linker were systematically modified to glycine. Serine to glycine changes in the ChitB linker resulted in higher susceptibility to truncation by Bz-cmp and altered substrate specificity for Bz-cmp and Es-cmp, such that different glycine-glycine peptide bonds were cleaved. Removal of the hevein domain led to loss of Es-cmp activity, indicating that interactions outside of the active site are important for recognition. Our findings demonstrate that plant class IV chitinases with polyglycine linkers are targeted for truncation by selective polyglycine hydrolases that are secreted by plant pathogenic fungi. This novel proteolysis of polyglycine motifs is previously unreported, but the specificity is similar to that of bacterial lysostaphin proteases, which cleave pentaglycine crosslinks from peptidoglycan. © 2014 Biochemical Society.

Peterson S.W.,Bacterial Foodborne Pathogens and Mycology Research Unit
PloS one | Year: 2013

During the course of mold surveys, a set of Talaromyces isolates were obtained that did not fit any described species. Phenotypic examination of these isolates showed that they were similar to T. piceus but differed in some growth characteristics. Multilocus DNA sequence data were obtained for the new isolates and some related species in the broader, more inclusive clade, and the data were analyzed using genealogical concordance. The new isolates are described as Talaromyces columbinus. From analysis of the related species, Penicillium rugulosum var. atricolum is given species status in Talaromyces as T. atricola. Penicillium tardum and P. chrysitis were showed to be synonyms of T. rugulosus. Penicillium scorteum and T. phialosporus were showed to be conspecific and under the rule of priority T. scorteus is the proper name for isolates previously known as T. phialosporus. Talaromyces wortmanii was showed to be distinct from Penicillium concavorugulosum and T. variabilis but the relationship of the latter two species remains unresolved. Examination of ITS sequences from GenBank showed that T. columbinus has previously been reported from human lung infections under the name Penicillium piceum.

Naumann T.A.,Bacterial Foodborne Pathogens and Mycology Research Unit | Price N.P.J.,Renewable Product Technology Research Unit
Molecular Plant Pathology | Year: 2012

Plant class IV chitinases have a small amino-terminal chitin-binding domain and a larger chitinase domain, and are involved in plant defence against fungal infection. Our previous work on the chitinases ChitA and ChitB from the model monocotyledon Zea mays showed that the chitin-binding domain is removed by secreted fungal proteases called fungalysins. In this article, we extend this work to dicotyledons. The effects of fungalysin-like proteases on four class IV chitinases from the model dicotyledon Arabidopsis thaliana were analysed. Four Arabidopsis chitinases were heterologously expressed in Pichia pastoris, purified and shown to have chitinase activity against a chitohexaose (dp6) substrate. The incubation of these four chitinases with Fv-cmp, a fungalysin protease secreted by Fusarium verticillioides, resulted in the truncation of AtchitIV3 and AtchitIV5. Moreover, incubation with secreted proteins from Alternaria brassicae, a pathogen of A.thaliana and brassica crops, also led to a similar truncation of AtchitIV3 and AtchitIV4. Our finding that class IV chitinases from both dicotyledons (A.thaliana) and monocotyledons (Z.mays) are truncated by proteases secreted by specialized pathogens of each plant suggests that this may be a general mechanism of plant-fungal pathogenicity. © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

Busman M.,Bacterial Foodborne Pathogens and Mycology Research Unit | Desjardins A.E.,Bacterial Foodborne Pathogens and Mycology Research Unit | Proctor R.H.,Bacterial Foodborne Pathogens and Mycology Research Unit
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2012

The ability of the fungus Fusarium proliferatum to cause kernel black point disease in wheat was previously established, but natural contamination of black point wheat with both F. proliferatum and fumonisin mycotoxins has not been studied in the United States. Low levels of fumonisins were detected in nine of 43 wheat samples with kernel black point disease that were obtained from across the United States. A subset of samples was contaminated with F. proliferatum as well as with F. fujikuroi, F. nygamai, F. thapsinum and F. verticillioides, species closely related to F. proliferatum and morphologically similar to it in that they produce chains of asexual spores, or conidia. Nevertheless, of conidial chain-forming fusaria isolated from symptomatic wheat, F. proliferatum dominated. In greenhouse tests, isolates of F. proliferatum and the other species recovered from wheat samples were able to cause symptoms of kernel black point and, in some cases, low levels of fumonisin contamination of wheat. These data add to the understanding of the risk of fumonisin contamination of wheat and the potential for Fusarium species to cause kernel black point disease and fumonisin contamination of wheat. Further, the results of this study indicate that while US-grown wheat can sporadically be contaminated by fumonisins, the natural contamination levels seem to be low. The observations made provide evidence that fumonisins are not likely to be a factor contributing to the ability of Fusarium to cause kernel black point disease. ©2012 Taylor & Francis.

Busman M.,Bacterial Foodborne Pathogens and Mycology Research Unit | Bobell J.R.,Bacterial Foodborne Pathogens and Mycology Research Unit | Maragos C.M.,Bacterial Foodborne Pathogens and Mycology Research Unit
Food Control | Year: 2015

Certain fungi that grow on crops can produce aflatoxins, which are highly carcinogenic. One of these, aflatoxin B1 can be metabolized by mammals to aflatoxin M1, a form that retains potent carcinogenicity and which can be excreted into milk. Direct analysis in real time (DART) ionization coupled to a high resolution mass spectrometer (MS) was used for the rapid quantitative analysis of a common form of aflatoxin, AFM1, extracted from cow milk. Sample preparation procedure and instrument parameter settings were optimized to obtain sensitive and accurate determination of AFM1. The lowest calibration level (LCL) for aflatoxin AFM1 was 0.1μg/kg. Quantitative analysis was performed with the use of matrix-matched standards employing a 13C-labeled internal standard for AFM1. DART-MS of spiked milk extracts gave linear response over the range of 0.1-2.5μg/kg. Good recoveries (94.7-109.2%) and repeatabilities (RSD 13.5-9.6%) were obtained at spiking levels of 0.5 and 2.0μg/kg. The results of the study further demonstrate the potential of ambient ionization-MS techniques for the sensitive, convenient and rapid quantitative determination of mycotoxins from difficult matrices. © 2014.

Taskin H.,Cukurova University | Kalaca S.B.,Cukurova University | Hansen K.,Swedish Museum of Natural History | O'Donnell K.,Bacterial Foodborne Pathogens and Mycology Research Unit
Mycologia | Year: 2012

The present study was conducted to better understand how the phylogenetic diversity of true morels (Morchella) in Turkey compares with species found in other regions of the world. The current research builds on our recently published surveys of 10 Turkish provinces and the northern hemisphere in which DNA sequence data from 247 and 562 collections respectively were analyzed phylogenetically. Herein we report on phylogenetic analyses of 243 additional collections made in spring 2009 and 2010 from eight additional provinces in the Aegean, Black Sea, central Anatolia, eastern Anatolia and Marmara regions of Turkey. Our analysis revealed that five species within the Esculenta clade (yellow morels) and 15 species within the Elata clade (black morels) were present in Turkey. Our preliminary results also indicate that M. anatolica, recently described from a collection in Muǧla province in the Aegean region of Turkey, is a closely related sister of M. rufobrunnea; these two species comprise a separate evolutionary lineage from the Esculenta and Elata clades. Nine species of Morchella currently are known only from Turkey, four species were present in Turkey and other European countries and seven species might have been introduced to Turkey anthropogenically. Three of the putatively exotic species in Turkey appear to be endemic to western North America; they are nested within a clade of fire-adapted morels that dates to the late Oligocene, 25 000 000 y ago. Our results indicate that there are roughly twice as many Morchella species in Turkey compared with the other regions of Europe sampled. Knowledge of Morchella species diversity and their biogeographic distribution are crucial for formulating informed conservation policies directed at preventing species loss and ensuring that annual morel harvests are sustainable and ecologically sound. © 2012 by The Mycological Society of America.

Naumann T.A.,Bacterial Foodborne Pathogens and Mycology Research Unit | Wicklow D.T.,Bacterial Foodborne Pathogens and Mycology Research Unit
Phytopathology | Year: 2010

Stenocarpella maydis causes both dry-ear rot and stalk rot of maize. Maize inbred lines have varying levels of resistance to ear rot caused by S. maydis. The genetic basis of resistance appears to rely on multiple genetic factors, none of which are known. The commonly used stiff-stalk inbred line B73 has been shown to be strongly susceptible to ear rot caused by S. maydis. Here, we report that the ChitA protein alloform from B73, ChitA-F, encoded by a known allele of the chiA gene, is susceptible to modification by a protein (Stm-cmp) secreted by S. maydis. We also identify a new allele of chiA (from inbred line LH82) which encodes ChitA-S, an alloform of ChitA that is resistant to Stm-cmp modification. Chitinase zymogram analysis of seed from a commercial field showed the presence of both ChitA alloforms in healthy ears, and showed that ChitAF but not ChitA-S was modified in ears rotted by S. maydis. The ChitA-F protein was purified from inbred line B73 and ChitA-S from LH82. ChitA-F was modified more efficiently than ChitA-S by S. maydis protein extracts in vitro. The chiA gene from LH82 was cloned and sequenced. It is a novel allele that encodes six polymorphisms relative to the known allele from B73. This is the first demonstration that the susceptibility to modification of a fungal targeted plant chitinase differs among inbred lines. These findings suggest that the LH82 chiA allele may be a specific genetic determinant that contributes to resistance to ear rot caused by S. maydis whereas the B73 allele may contribute to susceptibility.

Aoki T.,Japan National Institute of Agrobiological Science | Scandiani M.M.,Laboratorio Agricola Rio Parana | O'Donnell K.,Bacterial Foodborne Pathogens and Mycology Research Unit
Mycoscience | Year: 2012

A novel soybean sudden death syndrome (SDS) pathogen from Argentina and Brazil is formally described herein as Fusarium crassistipitatum based on detailed phenotypic analyses of macro- and microscopic characters and phylogenetic analyses of multilocus DNA sequence data. Fusarium crassistipitatum can be distinguished from the other soybean SDS and bean (Phaseolus/Vigna) root rot pathogens (BRR) phenotypically by the production of yellowish colonies on PDA; and tall, stout, and mostly unbranched conidiophores with a thick-walled base, which form multiseptate conidia apically. Phylogenetic species recognition based on genealogical concordance of a six-gene dataset strongly supported the reciprocal monophyly of F. crassistipitatum with respect to the other SDS and BRR pathogens. Isolates of F. crassistipitatum were able to induce typical SDS foliar and root rot symptoms on soybean that were indistinguishable from those caused by three other SDS pathogens (i. e., F. virguliforme, F. brasiliense, and F. tucumaniae) on susceptible cultivars A-6445RG and N-4613RG in a pathogenicity experiment. © 2011 The Mycological Society of Japan and Springer.

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