A prebiotic, Celmanax™, decreases Escherichia coli O157:H7 colonization of bovine cells and feed-associated cytotoxicity in vitro

<p>Abstract</p> <p>Background</p> <p><it>Escherichia coli </it>O157:H7 is the most common serovar of enterohemorrhagic <it>E. coli </it>associated with serious human disease outbreaks. Cattle are the main reservoir with <it>E. coli </it>O157:H7 inducing hemorrhagic enteritis in persistent shedding beef cattle, however little is known about how this pathogen affects cattle health. Jejunal Hemorrhage Syndrome (JHS) has unclear etiology but the pathology is similar to that described for <it>E. coli </it>O157:H7 challenged beef cattle suggestive that <it>E. coli </it>O157:H7 could be involved. There are no effective treatments for JHS however new approaches to managing pathogen issues in livestock using prebiotics and probiotics are gaining support. The first objective of the current study was to characterize pathogen colonization in hemorrhaged jejunum of dairy cattle during natural JHS outbreaks. The second objective was to confirm the association of mycotoxigenic fungi in feeds with the development of JHS and also to identify the presence of potential mycotoxins. The third objective was to determine the impact of a prebiotic, Celmanax™, or probiotic, Dairyman's Choice™ paste, on the cytotoxicity associated with feed extracts <it>in vitro</it>. The fourth objective was to determine the impact of a prebiotic or a probiotic on <it>E. coli </it>O157:H7 colonization of mucosal explants and a bovine colonic cell line <it>in vitro</it>. The final objective was to determine if prebiotic and probiotic feed additives could modify the symptoms that preceded JHS losses and the development of new JHS cases.</p> <p>Findings</p> <p>Dairy cattle developed JHS after consuming feed containing several types of mycotoxigenic fungi including <it>Fusarium culmorum</it>, <it>F. poae</it>, <it>F. verticillioides</it>, <it>F. sporotrichioides</it>, <it>Aspergillus</it><it>flavus</it>, <it>Penicillium roqueforti, P. crustosum, P. paneum </it>and <it>P. citrinum</it>. Mixtures of Shiga toxin - producing <it>Escherichia coli </it>(STEC) colonized the mucosa in the hemorrhaged tissues of the cattle and no other pathogen was identified. The STECs expressed Stx1 and Stx2, but more significantly, Stxs were also present in the blood clot blocking the jejunum. Mycotoxin analysis of the corn crop confirmed the presence of fumonisin, NIV, ZEAR, DON, 15-ADON, 3-ADON, NEO, DAS, HT-2 and T-2. Feed extracts were toxic to enterocytes and 0.1% Celmanax™ removed the cytotoxicity <it>in vitro</it>. There was no effect of Dairyman's Choice™ paste on feed-extract activity <it>in vitro</it>. Fumonisin, T-2, ZEAR and DON were toxic to bovine cells and 0.1% Celmanax™ removed the cytotoxicity <it>in vitro</it>. Celmanax™ also directly decreased <it>E. coli </it>O157:H7 colonization of mucosal explants and a colonic cell line in a dose-dependent manner. There was no effect of Dairyman's Choice™ paste on <it>E. coli </it>O157:H7 colonization <it>in vitro</it>. The inclusion of the prebiotic and probiotic in the feed was associated with a decline in disease.</p> <p>Conclusion</p> <p>The current study confirmed an association between mycotoxigenic fungi in the feed and the development of JHS in cattle. This association was further expanded to include mycotoxins in the feed and mixtures of STECs colonizing the severely hemorrhaged tissues. Future studies should examine the extent of involvement of the different STEC in the infection process. The prebiotic, Celmanax™, acted as an anti-adhesive for STEC colonization and a mycotoxin binder <it>in vitro</it>. Future studies should determine the extent of involvement of the prebiotic in altering disease.</p

Deoxynivalenol Biosynthesis-Related Gene Expression During Wheat Kernel Colonization by \u3ci\u3eFusarium graminearum\u3c/i\u3e

Deoxynivalenol (DON) is a potent mycotoxin and virulence factor produced by Fusarium graminearum. We examined the expression of the core DON biosynthetic gene Tri5 during wheat head infection of susceptible and resistant cultivars and susceptible cultivars treated with strobilurin fungicides (e.g. azoxystrobin). DON was quantified to correlate expression with toxin accumulation. The highest Tri5 expression relative to housekeeping genes occurred at the infection front. As infection progresses, earliest-infected kernels showed diminished relative Tri5 expression but Tri5 expression never ceased during the 21 days observed. Azoxystrobin treatment showed no significant effect on either relative Tri5 expression or DON quantity. The resistant cultivar \u27Alsen\u27 showed minimal spread of the fungus, with no fungus detected by day 21. DON was not detected in significant quantities in Alsen in the later stages sampled. In Wheaten, DON levels were negligible at 8 days post-inoculation (dpi), with detectable DON at later-sampled time points. Tri5 was detected even in fully senesced kernels 21 dpi. Our data demonstrate the presence of Tri5 transcripts in a susceptible cultivar over a much longer time period than has been previously documented. This suggests the ability of the fungus to rapidly resume toxin biosynthesis in dried infected grain should conducive environmental conditions be present, and provides a possible mechanism for high DON levels in asymptomatic grain

Root cortical anatomy is associated with differential pathogenic and symbiotic fungal colonization in maize

Root anatomical phenotypes vary among maize (Zea mays) cultivars and may have adaptive value by modifying the metabolic cost of soil exploration. However, the microbial trade-offs of these phenotypes are unknown. We hypothesized that nodal roots of maize with contrasting cortical anatomy have different patterns of mutualistic and pathogenic fungal colonization. Arbuscular mycorrhizal colonization in the field and mesocosms, root rots in the field, and Fusarium verticillioides colonization in mesocosms were evaluated in maize genotypes with contrasting root cortical anatomy. Increased aerenchyma and decreased living cortical area were associated with decreased mycorrhizal colonization in mesocosm and field experiments with inbred genotypes. In contrast, mycorrhizal colonization of hybrids increased with larger aerenchyma lacunae; this increase coincided with larger root diameters of hybrid roots. F. verticillioides colonization was inversely correlated with living cortical area in mesocosm-grown inbreds, and no relation was found between root rots and living cortical area or aerenchyma in field-grown hybrids. Root rots were positively correlated with cortical cell file number and inversely correlated with cortical cell size. Mycorrhizae and root rots were inversely correlated in field-grown hybrids. We conclude that root anatomy is associated with differential effects on pathogens and mycorrhizal colonization of nodal roots in maize

One fungus, one name: defining the <i>genus Fusarium</i> in a scientifically robust way that preserves longstanding use

In this letter, we advocate recognizing the genus Fusarium as the sole name for a group that includes virtually all Fusarium species of importance in plant pathology, mycotoxicology, medicine, and basic research. This phylogenetically guided circumscription will free scientists from any obligation to use other genus names, including teleomorphs, for species nested within this clade, and preserve the application of the name Fusarium in the way it has been used for almost a century. Due to recent changes in the International Code of Nomenclature for algae, fungi, and plants, this is an urgent matter that requires community attention. The alternative is to break the longstanding concept of Fusarium into nine or more genera, and remove important taxa such as those in the F. solani species complex from the genus, a move we believe is unnecessary. Here we present taxonomic and nomenclatural proposals that will preserve established research connections and facilitate communication within and between research communities, and at the same time support strong scientific principles and good taxonomic practice

One Fungus, One Name: Defining the Genus Fusarium in a Scientifically Robust Way That Preserves Longstanding Use.

In this letter, we advocate recognizing the genus Fusarium as the sole name for a group that includes virtually all Fusarium species of importance in plant pathology, mycotoxicology, medicine, and basic research. This phylogenetically guided circumscription will free scientists from any obligation to use other genus names, including teleomorphs, for species nested within this clade, and preserve the application of the name Fusarium in the way it has been used for almost a century. Due to recent changes in the International Code of Nomenclature for algae, fungi, and plants, this is an urgent matter that requires community attention. The alternative is to break the longstanding concept of Fusarium into nine or more genera, and remove important taxa such as those in the F. solani species complex from the genus, a move we believe is unnecessary. Here we present taxonomic and nomenclatural proposals that will preserve established research connections and facilitate communication within and between research communities, and at the same time support strong scientific principles and good taxonomic practice