Introduction to Fungi, Third Edition

EUROTIALES
307
are uncommon, with the major exception of
P. marneffei. As already noted, this species grows as
a fission yeast at 37°C, and it causes systemic and
disseminated infections in South East Asia which
have increased dramatically with the spread of
AIDS there. The disease symptoms are similar
to those of Histoplasma capsulatum (see p. 290),
including the predominance of the disease in
male patients (Harrison & Levitz, 1996). Disseminated
infections are most commonly found in
lung, liver and skin and can be treated with
amphotericin B and itraconazole (Harrison &
Levitz, 1996). Penicillium marneffei can be isolated
with high frequency from the internal organs of
bamboo rats as well as their burrows in South East
Asia. However, since contact between these
rodents and humans is probably infrequent,
there may be unknown sources of inoculum in
the environment to which both rats and humans
are exposed (Vanittanakom et al., 2006).
11.4.6 Byssochlamys
Byssochlamys is a small genus of soil fungi
currently comprising four species (Pitt et al.,
2000) which are noteworthy because of their
thermotolerance. The most tolerant structures
are the ascospores which may survive heating to
90°C for 25 min, especially in the presence of
high sucrose concentrations (Beuchat & Toledo,
1977; Bayne & Michener, 1979). Byssochlamys spp.
are important contaminants of canned fruits or
bottled fruit juices (Tournas, 1994) because of
their heat tolerance, ability to produce pectolytic
enzymes, and tolerance of conditions of low
oxygen tension. Contamination can be dangerous
because Byssochlamys spp. can produce several
mycotoxins, including patulin (Rice et al., 1977).
Another habitat associated with human activity
is silage in which Byssochlamys is a common
contaminant (Inglis et al., 1999). In nature,
Byssochlamys is ubiquitous in the soil. In orchards,
it may be splashed onto the fruit prior to or
during harvesting.
In culture, Byssochlamys spp. reproduce asexually
by the formation of chains of hyaline conidia
derived from tapering open-ended phialides
(Fig. 11.15a) which have been assigned to the
Paecilomyces type. Terminal, thick-walled
Fig11.15 Byssochlamys nivea.
(a) Phialospores and
chlamydospores. (b) Coiled
ascogonium surrounding an
antheridium. (c) Ascogonium
bearing ascogenous hyphae
which in turn produce asci.
Note the absence of sterile
investing hyphae.