Re: Stachybotrys versus Chaetomium

[Guest guest]

,

" Microbial Growth in Indoor Environments " by Flannaigan p. 39 list the

water activity of Stachy at 0.94. and 0.91-0.93 from two references.

On the other hand, EMSL reports the water activity for Chaetomium as

0.84-0.89.

Also there are differences in growth rates at the same temperature for

these genera/species.

Bob

[Guest guest]

Perhaps one of the determining factors for the growth

of Stachybotrys or Chaetomium in a certain location

would be the presence of which viable spores in that

location when the opportunities arise.

Wei

QLAB

--- Bob s wrote:

> ,

>

> " Microbial Growth in Indoor Environments " by

> Flannaigan p. 39 list the

> water activity of Stachy at 0.94. and 0.91-0.93

> from two references.

>

> On the other hand, EMSL reports the water activity

> for Chaetomium as

> 0.84-0.89.

>

> Also there are differences in growth rates at the

> same temperature for

> these genera/species.

>

> Bob

>

>

>

>

>

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[Guest guest]

,

Chaetomium globosum is an ascomycete and produces a perithecium, an enclosed

capsule of spores, unlike the delicate conidiophores ( " fruiting bodies " ) of

Aspergillus or Penicillium molds. In my experience, the perithecia remain

intact for months (unless munched open by mold-eating mites or other

insects, in which case fecal pellets full of barely-digested spores are

present).

The condition of wetness may have something to do with the presence of a

particular mold (I observed black mold on two different sides of below grade

drywall that had been dampened from a single floor water event, but the

room-facing side was Ulocladium mold and the backside was Chaetomium mold,

giving the impression that " toxic black mold " had grown through the

gypsum!)but the difference could also be due to what is in the paper to

begin with.

Stachybotrys spores in my experience are less common in air samples indoors

than Chaetomium spores and, according to Roberston, ( " Monitoring Viable

Fungal and Bacterial Bioaerosol Concentrations to Identify Accptable Levels

for Common Indoor Environmments, " Indoor and Built Environment, 1997)occur

in 1% versus 2% resp. of indoor samples (both low numbers).

What I find surprising is that compared to other species of spores that

occur so much more frequently in air, how is is that the rare S. chartarum

apores always finds their way indoors and specifically into wall cavities;

and judging from the number of individual colonies (from possibly single,

germinated spores), in such relatively large numbers?

I would like to hear some other opinions or see references to studies, but

in my opinion, the spores must already be present in the paper of the

drywall. (I recall someone on this Board having tested this theory by

placing damp drywall in a plastic bag and observing S. chartarum growth.)

I tried successive tape lifts at one location of a piece of clean drywall

but got tired of looking at the samples after about 20 tries, with unknown

numbers of trials yet ahead before reaching the plaster.

It would make sense that paper manufacturing vats containing constantly wet

cellulose would have such growth.

I also wonder to what extent the starch in the drywall paper (up to 1%)

provides nutrients for all the molds that grow.

C. May

May Indoor Air Investigations LLC

1522 Cambridge Street

Cambridge, MA 02139

www.mayindoorair.com

www.myhouseiskillingme.com

Nunez writes:

> Group:

>

> Has anybody looked at why Stachybotrys chartarum grows in some cases

> after a leakage, and in others cases you almost find pure cultures of

> Chaetomium globosum? Both have same preferences when it comes to Aw,

> temperature, substrate... or not?

>

> I have the feeling that Ch. globosum grows after a sudden leakage with

> lots of water available, while Stachybotrys goes more for substrates

> which are wet for a long time. It is not rare to find them growing

> together, though...

>

> Question nr. 2: How long can Chaetomium globosum fruitbodies last after

> they are formed? Months, years??

>

> Mould ecology is interesting and can help understanding mould damages in

> buildings.

> Nunez

> Ph. D.

> Mycoteam As

> Norway

> maria.nunez@...