Journal of Film Preservation - FIAF

Les études consacrées à ce problème
confirment l’hypothèse que la
pellicule est particulièrement sensible
à la contamination par bactéries et
champignons, spécialement quand
ces matériaux sont conservés dans
des conditions inappropriées
favorisant la prolifération
microbienne.
Les auteurs concluent que c’est par
l’adoption de mesures de
conservation appropriées et l’examen
périodique préventif des matériaux de
collection qu’on pourra réduire les
risques de détérioration microbienne
de la pellicule cinématographique.
Fig. 2 Types of factors involved in
biodegradation.
acetate and gelatine will be highlighted, and finally, current
information about the biodegradation of motion picture stocks will be
summarised.
Biodegradation, Bacteria and Filamentous Fungi
Biodegradation is any biological process involving a decline in the
quality (aesthetic, functional, commercial, etc.) value of a product or
material. This negative change is usually produced by micro-organisms,
although other organisms (molluscs, crustaceans and so on) can also
contribute. In general, this process includes the degradation or
transformation of one or more components of a determinate material,
and, therefore, it involves a change in its chemical composition.
Microbial biodegradation is really a very complex process, because it
depends on many different factors, which can be separated into three
groups :
a) Intrinsic factors; they are characteristic of the material, such as pH,
nutrient composition, available water content (aw ) and so on.
b) Extrinsic factors; they are the environmental storage conditions, for
instance, moisture percentage, temperature and environmental pH.
and c) Implicit factors; they involve micro-organisms and in particular
their physiology.
These three groups of factors are interrelated and their combined effect
is the bio-deterioration process (Fig. 2).
Although microbial studies are scarce, as discussed later in the paper the
main micro-organisms involved in biodegradation of motion picture film
components are certain bacteria and filamentous fungi10 . These are very
different11 , and use different compounds of carbon as energy sources.
Bacteria are prokaryotic unicellular micro-organisms. In general, they
are 1-10 micrometers in length and appear isolated or in cellular
aggregations. Bacterial shapes are quite diverse; they can be cylindrical
(bacilli), spherical (coca), helicoidal (spirilli) or curved-rods (vibria) (Fig.
3). Bacteria are prokaryotic because they have no nuclear envelope, and
the circular chromosome is placed within the cytoplasm. In addition,
they do not have complex cytoplasmic organs (Golgi apparatus,
endoplasmic
reticulum, etc.) and
the ribosomes, the
organ involved in
protein
biosynthesis, are
smaller (70 S) than
eukaryotic
ribosomes (80 S).
Bacteria have high
metabolic and
nutritional
diversity, and they
can grow in the
presence of oxygen (aerobic) or in the absence of oxygen (facultative or
strict anaerobes).
39 Journal of Film Preservation / 67 / 2004