Olga L.Smolyanitskaya, T.Velikova,

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Evaluation of Spore Presence and Viability by Air and Contact Sampling


Olga
L.
Smolyanitskaya, T.Velikova,
M. Rakotonirainy, A. Gorbushina


Beurteilung der Existenz und der Lebensfähigkeit von Sporen mit verschiedenen Methoden der Luft
-

und Kontakt
-
Probenn
ahme


In vier historischen Gebäuden in St. Petersburg und Paris wurde eine Forschungsreihe zur
Pilzausbreitung durchgeführt. Verschiedene Techniken der Luftuntersuchung (z.B. volumetrische
Luftprobennahme und Sedimentation) und zur Analyse des Oberflächen
befalls (Wischtester,
Petrifilme, sterile feuchte Baumwollpapierscheiben, Methode nach Koch) kamen zur Anwendung.
Laut der Testergebnisse waren nicht die Besucher, son
dern der Wartungszustand der Klimaanlage
für die Verbreitung der Pilze in den Aus
stellu
ngsräumen verantwortlich. Im Vergleich erweisen
sich Wischtester als die beste Methode in der Beurteilung des Befalls auf der Oberfläche von
Kunstobjekten.


Various techniques for analysing the air (e. g. volumetric and sedimentation) and the con
taminatio
n
of surfaces (e.g. culture swab, Petrifi/ms™, Rodac plates and paper disks) were carried out in four
historic buildings in St. Petersburg and Paris. The results indicated that the levels of airborne fungi
in the exhibition rooms depended on the operating
condi
tions of the ventilation system, and not on
the presence of visitors. Compared to other methods, the culture swabs proved to be the most
suitable for the assessment of the con
tamination level of surfaces of art objects.


Introduction

The control of
fungal levels in museum buildings, both in air and on surfaces, is an im
portant part
of the preventive conservation of art objects.

Fungi are part of the normal environment and therefore always present in buildings
-
both in the
indoor air and on surfaces.

Microorganisms from the outdoor air manage to get into museum
buildings through ventilation ducts; some microorganisms are of human origin. Archaeological
objects are often very seriously contaminated and need special cleaning.

The numerous reports concer
ning fungal influence on human health should receive spe
cial
attention.
1
'
2

This is especially important for museum staff working with seriously contaminated
objects. The main means in the control of microbial contamination is the control of moisture, but
many museums, mostly located in old buildings, still suffer from mould problems due to damaged
foundations or roof leaks.
3
'
4
An evaluation of mould numbers in museums and libraries is important
not only in cases of the violation of microclimatic parameters
, but also in cases, which seem to be
rather safe for storage buildings. Not only storages, but also restoration workshops and exhi
bition
areas should be under observation. Control of storage and exposition state decreases the probability
of the undesirab
le contamination with fungi on both cultural monuments and people.

Moisture increase and insufficient airflow circulation result in the sedimentation of micro
organisms
and dust on the surfaces of exhibits, documents, shelving, showcases, walls, and so on.

Therefore it
is necessary to combine the investigations of both air and exhibit surfaces in order to evaluate the
state of the indoor environment of museums. Sampling methods, recommended for routine museum
monitoring and for mass analysis of museum
objec
ts, must be suitable for museum practice.
Besides, application of some or other methods can be restricted due to the potential effect on
monument material. The aim of this study was the assessment of fungal counts in four historic
buildings and the evaluat
ion of the efficiency of some techniques recommended for museums,
archives and libraries.


Materials and methods

Different rooms of architectural value in museums, archives and libraries located in build
ings of the
18
th

century were investigated: the Stat
e Hermitage Museum (SH) and the National Library of
Russia (NLR) in St. Petersburg, the National Archives of France (NA) and the Inter
-
University
Library for Oriental Languages (ILJLOL) in Paris. The sampling was conducted during winter
1999
-
2000
(SH and N
LR) and spring
2000
(NA and ILJLOL).
516
air and
221
surface samples
were analyzed. In the exhibition halls and storages of SH various means are used to stabilise the
microclimate. An HVAC system operates only in several halls of the ground and 1
st

floors
of the
New Hermitage building; in other rooms heat supply and ventilation come through air channels in
building walls. Rooms in NLR, NA and IULOL are ventilated naturally. Numbers of airborne fungi
were investigated with the use of samplers of various modi
fications and by the sedimentation plates
method. An MD
-
8 sampler (Sartorius, Germany) was used in SH to perform volumetric investiga
-
tions. On sampling, air was passed through gelatin filters that trapped microorganisms. Gelatin
membrane filters, being in
herently moist, prevented microorganisms from drying in the airflow.
Then the filters were transferred on
2 %
malt
-
agar (MA) in Petri dishes. Air volumes selected for
investigation equalled
300
1. The analysis of the air environment in NA and IULOL was carr
ied out
using a portable MAS
-
100 impactor (Merck, Germany), based upon spore sedimentation directly on
MA in the Petri dish, which is fixed in the sampler. Volumes of
100
and
250
1 were used. The
results were expressed as the num
ber of colony forming units

per cubic meter (CFU/m
3
) of sampled
air. Simultaneously with the volumetric method at the SH, NA and IULOL, we carried out sampling
with the sedimentation plates method: Petri dishes (with a diameter of
90
and 100 mm) were placed
at
5
sites in each room a
nd exposed for 60min. Results were ex
pressed as CFU/plate. The level of
contamination on object surfaces was evaluated with culture swabs, Petrifilms™, Rodac plates and
paper disks. The surfaces of furniture and documents were investigated using two conta
ct methods:
culture swabs and filter paper disk impressions. Additionally, Rodac plates and 3M™ Petrifilms™
were used for the analysis of shelving and wall surfaces. Culture swabs were used to analyze
surfaces of 30 cm
2
. Swabs were shaken in distilled wate
r and series of dilutions were prepared from
the washings. Aliquots of each dilution were spread on the surface of MA in Petri dishes.

Sterilized filter paper disks
(4
cm diameter), previously moistened with sterilized distilled water,
were applied to the
surface under investigation for several seconds and then transferred into Petri
dishes with MA for
30
min.

Rodac plates
(5.5
cm diameter) containing MA were prepared in the laboratory. On an
alyzing, the
Rodac plates were applied to the investigated surfac
e for several seconds. Petrifilms™ are ready
-
to
-
use films (30 cm
2
) coated with jellified dehydrated culture medium (Sabouraud
agar
modified). One
hour before use the culture medium was re
-
hydrated with
1
ml of sterilized distilled water. The top
film was a
pplied with its sticky layer to the analyzed surface for several seconds, and then the plate
was folded up and placed in an incubation chamber.

The Petri dishes were incubated at
26
°C; colony counting with following identification was
performed on the 3
rd
-
7
th

day depending on the growth rate of fungi. The results were expressed as
the number of colony forming units per square decimeter (CFU/dm
2
) of surface.


In IULOL we used each of the four contact methods, but in SH and NLR we only used two
methods: cult
ure swabs and filter paper disks due to the impossibility to apply Rodac plates and
Petrifilms™ to museum objects.


Results and discussion

Applied modifications of volumetric methods allowed to evaluate quantity and change of fungal
levels in the rooms inv
estigated.


Tab.
1
Main indoor airborne fungi numbers (CFU/m
3
) before and after midday

A.State
Hermitage Museum (December
2000)



B. National Archives of France (April
-
May
2001)



Ventilation and means ensuring a microclimate had a major influence on th
e state of the air
environment of the examined rooms. The results obtained at the SH revealed that the numbers of
airborne fungi were considerably lower in halls equipped with HVAC system than in halls with air
supply system. Fungal numbers in the air vari
ed from
61
-
63
CFU/m
3
to
127
-
168
CFU/m
3

respectively. All air samples taken in the halls with HVAC systems contained fungal counts several
times lower than in the other parts of the museum and the level of fungi remained constant during
the day. Air
-
condit
ioning systems may be re
sponsible for disorders and pathologies related to
microorganism proliferation.
5
'
6

On the other hand, correct operating and maintaining air
-
conditioning plays a role in the re
duction of indoor airborne microorganisms.
7,8

Airborne
fungi counts in the exhibit halls of SH were mainly affected by ventilation sys
tem work,
but not by the presence of visitors. Mould numbers in the air of "Palace of Pe
ter I" (exhibition of
SH which consists of relatively small halls) depended on the degr
ee of protection of filters in the
system of the air supply operating during daytime (Tab.
2).
The numbers of airborne fungi in SH
and NA were estimated before and after midday. In the SH there was a tendency of airborne fungi
numbers to be lower in the af
ternoon in both halls of large area (up to
800
m
2
) and in exhibit rooms
of less area
(30
-
50
m
2
),


Tab.
2
Influence of the filters with various degrees of protection on airborne fungal counts
(CFU/m
3
) in the halls of "Palace of Peter l" exposition (January
2001)



excluding halls equipped with HVAC system. In NA the fungal counts after midday were
13
-
57%
lower depending on the room.

Results obtained with sedimentation plates were very disperse. The numbers measured were
0
-
41
CFU/plate at SH,
0
-
13
CFU/plate
at NA and
0
-
35
CFU/plate at IULOL The sedimentation method
did not enable us to determine reliably small changes in fungal counts in air during the day. The
ratio between aspiration and sedimentation method as obtained in SH was equal to 42±
17,
and
accord
ing to data obtained in NAand IULOL it was equal to 30±
12.
The sedimentation plate
method has a number of disadvantages and is of
ten considered as unreliable, but it is still in use.
Since the method is simple and does not require special equipment, it i
s evident that it will be used
for long in libraries and museums. The comparison of data obtained via different contact methods in
NA, IULOL, SH and NLR arranged these methods of surface investigation according to the number
of detected colonies as follows
: culture swabs
>
Petrifilms™
>
Rodac plates
>
Paper disks (Tab.
3).



Tab.
3
Main values of fungal counts (CFU/dm
2
) on the surfaces obtained via various methods


The culture swabs method enabled us to detect the largest fungal numbers. Besides, this method is
applicable t
o the surfaces of works of art as it practically has no effect
on
the ma
terial.

The use of Rodac plates and Petrifilms™ in museums and libraries is significantly limit
ed by the
traces of nutritious mediums remaining on the investigated surfaces, but they

can be successfully
applied in mass investigations of walls, furniture and shelving in storages of museums and libraries.
In spite of the least fungal counts as compared with other methods, the use of paper disks is justified
in the analysis of surfaces o
f docu
ments during the last ten years in NLR. This method can be
recommended as simple and suitable for the monitoring of fungi in museums and libraries.


Acknowledgements

The research was supported by the International Center for Preservation in St. Pete
rsburg. We wish
to thank all the staff at the Research Center for Graphical Document Conser
vation in Paris for
support and collaboration.

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