The fungi: how they
grow and their effects on human health. (includes
related article on documentation of fungal
exposure and disease relationship) Date: 07-01-1997;
Publication: Heating, Piping, Air Conditioning;
Author: Burge, Harriet A.
<SNIP>
Shape and structure
of fungi
"The fungal cell
is similar to that. of plants and animals, containing
all of the same organelles (nucleus, mitochondria,
ribosomes, membrane systems, etc.). Like plants,
the fungal cell is bounded by a rigid cell wall.
However, while plant cell walls contain cellulose
as the basic structural material, fungal cell
walls contain a material that is similar to
that in insect exoskeletons (chitin). Most fungal
walls also contain substances called glucans
that can be toxic to animal cells."(Burge,
Harriet A.. 1997))
Very interesting
that fungal cell walls are made up of the
same material
as our pet's exoskeleton - chitin - while
also containing a material -
glucans- that can be toxic to animals.
"Temperature also
plays a direct role in the colonization of surfaces
with fungi. At relatively low temperatures (50
to 60 F), spores take longer to germinate and
growth is slower to become established than
at, say, 60 to 70 F. Water activity optima are
usually higher at low temperatures than at high.
This means that high water activity levels must
be maintained for longer periods in cold than
in warm environments for growth to occur."(ibid)
Ok ... as anyone
who lives in a humid climate knows ... as
heat and dampness rises, so does the amount
of mold you must scrub out of your bathroom!
Obviously ... a crabitiat is a substrate made
in Fungi- heaven, both warm and damp. So is
there anything in the latter part that may
help us make our hermies home less compatible
with fungal growth?
"Carbon, nitrogen,
and a variety of mineral elements are also essential
for fungal growth. There are fungi that can
use most complex carbon-containing compounds,
but most favor sugars, with some able to utilize
cellulose and lignin. Fungi are unique in their
ability to degrade the latter two highly resistant
polymers."(ibid)
Wondering if this
is why Don only placed Treat in his tank every
few
days and only for 24 hours? Alabama is right
up there in the fungus
rich states!
"Nitrate or ammonia
can provide nitrogen to fungi as can amino acids
and proteins. A common nitrogen source for dust-borne
fungi is keratin, the structural protein from
human skin. Again, fungi are among very few
organisms that can degrade this highly resistant
polymer. The mineral element needs of fungi
are met by trace amounts of these necessary
nutrients that occur as part of the carbohydrates
and proteins used as carbon and nitrogen sources
and dissolved in water."(ibid)
Well .. this is
a case for a glass or plexi lid over a screened
or aquarium hood. The more airbourne elements,
both fungal spores and keratin (from your
skin and hair) that you can keep out of the
crab tank, the less the chance of fungal infestation,
or its growth. Right?
"In the process
of degrading complex carbohydrates and proteins
to release essential nutrients, fungi produce
carbon dioxide, water, and a variety of other
compounds that range from volatile aldehydes,
alcohols, and ketones to complex secondary metabolites,
including antibiotics and mycotoxins. The volatile
compounds are responsible for the odors commonly
associated with fungal growth, and although
their health impact has not been studied, these
odiferous compounds are [TABULAR DATA FOR TABLE
1 OMITTED] blamed for a variety of building-
related complaints."(ibid)
And we know what
offgassing of the above aldehydes, ketones,
and others can do to a
crab's gill system.
"Although most fungi
probably produce these secondary metabolites,
the conditions under which they do so are not
clear, and it is likely that production is highly
substrate-dependent."(ibid)
And for this reason
.. it is a good idea for us to continue to
watch for more research on fungal growth and
development. If they can begin to identify
substrate conditions that encourage growth,
it may lead us as crabbers to different choices
of tank substrates and equipment.
"Fungi in the environment
Fungi are responsible for most aerobic (oxidative)
decay processes in the environment and play
an essential role in the natural ecosystem.
For example, fungi turn fallen leaves and dead
trees into soil by digesting the complex carbohydrates
(cellulose, lignin) into soluble forms. Composting
utilizes this natural ability of fungi to process
dead organic material. In colonizing building
materials, which contain dead organic material,
fungi are merely fulfilling their mission within
the natural ecosystem."(ibid)
Hence the reason
organic material substrates are often discouraged
for use within a crabitat.
"Fungal-related
diseases Allergies (hay fever, asthma, allergic
pneumonia) are caused by exposure to agents
that stimulate a disease-causing immune response."(ibid)
Hey! They're talking
about me!
"The development
of an allergy is a two-step process. The first
step is exposure to an allergen that causes
sensitization but no symptoms. Allergens are
usually proteins that are often derived from
living organisms (Table 1). Sensitization means
that the immune system has been stimulated to
produce antibodies or activated cells that specifically
recognize the allergen. The second step is symptom
development, which requires exposure to an allergen
after sensitization has occurred. Such exposure
leads to the release of chemicals such as histamine
that are powerful irritants, causing redness,
swelling, and, i.n some cases, permanent changes
in lung tissue."(ibid)
Wow .... this is
off topic but it is a great and highly factual
description of how an allergy develops and
how the immune system is effected! The rest
of the description is really good too.
Conclusion Fungi are unique organisms,
many of which can utilize building materials
as food sources, provided adequate water is
present.
Ok ... the conclusion
is no surprise here, what was interesting
and new to me is that the process by which
the fungi convert elements into nutrients
results in the off gassing of toxins that
we know are trouble for our pets. I'd more
or less figured it was by direct tissue infection
that crabs were affected. according to this
article, the presence of mold could also be
a source gill stress. So mold at any time,
anywhere within a crabitat can quickly become
a health hazard.
Jenn
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Article
Reference:
Burge, Harriet A.(1997).
The fungi: how they grow and their effects on
human health. (includes related article on documentation
of fungal exposure and disease relationship)
Date: 07-01-1997; Publication: Heating, Piping,
Air Conditioning;
Note: Ibid means that
the same reference was being quoted repeatedly
eg. it was the same journal article, and not
another source each time. For more information,
view this article.
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