Biomedical Engineering Reference
In-Depth Information
penicillic acid, viomellein and xanthmegnin), Penicillium brevicompactum
(mycophenolic acid) and Penicillium verrucosum (ochratoxin A and citrinin)
(Frisvad and Thrane 1995).
Fusarium spp.
Fusarium is a large genus of fi lamentous fungi widely distributed in soil
and in association with plants. Most of the Fusarium species are plant
pathogens, some species may cause a range of opportunistic infections in
humans. In humans with normal immune systems, fusarial infections
may occur in the nails and in the cornea (keratomycosis or mycotic
keratitis). In humans whose immune systems are weakened in a particular
way, (neutropenia, i.e., very low neutrophils count), aggressive fusarial
infections penetrating the entire body and bloodstream (disseminated
infections) may be caused by members of the Fusarium solani , Fusarium
oxysporum , Fusarium verticillioides , Fusarium proliferatum and rarely, other
fusarial species. Majority of Fusarium species are produce mycotoxins in
cereal crops that can affect human and animal health if they enter
the food chain. The main toxins produced by these Fusarium species
are fumonisins and trichothecenes.
The genus Fusarium consists of species that attack almost all food crops
grown. Out of 101 most economically important plants, at least 81 are hosts
of Fusarium pathogens. Fusarium can cause disease at any stage of the plant
growth and the types of diseases are quite varied and may include seed rot,
seedling blight, root rot, stalk rot, ear rot, kernel rot, head blight, cankers,
wilts and leaf diseases. These species were common in Alimentary toxic
aluekia outbreaks (ATA) in the Soviet Union during World War II, which
caused high T-2 toxin levels in different overwintered crops including
wheat and millet (Desjardins 2006, Yli-Mattila and Gagkaeva 2010).
Toxin-producing fusaria are diffi cult to study because strains with similar
morphology represent different biological groups that include endophytes
(Leslie et al. 1990; Bacon and Hinton 1996), saprophytes (Fracchia et al.
2000) and plant pathogens (Chandra et al. 2008). That is the reason why
it is diffi cult to establish systems of taxonomy for Fusarium species and
therefore the importance of molecular methods to differentiate the taxa
is emphasized. Another remarkable characteristic of the toxigenic fusaria
is that each species synthesizes compounds common to several species as
well as families of compounds that are species specifi c (Emokhonov et al.
1993). From the chemical point of view, Fusarium toxins are characterized
by diverse structures like polyketides, terpenoides, amino acid derivatives,
etc., with correspondingly signifi cant differences in their biological activity.
In some cases, relatively small changes in the chemical structure of the toxin
can result in a signifi cant difference in its activity.
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