Journal of Film Preservation - FIAF

las películas son particularmente
sensibles a la contaminación por
bacterias y hongos, sobre todo cuando
estos materiales se conservan en
condiciones inapropiadas provocando
la proliferación microbiana.
Las buenas condiciones de
preservación y el examen periódico
preventivo de los materiales de
colección reducirán los riesgos de
deterioro microbiano de las películas
cinematográficas, concluyen los
autores.
Microorganism
Bacteria
Lower limit Optimum pHw Higher limit
Pseudomonas aeruginosa 5.6 6.6 - 7.0 8.0
Bacillus pasteurii 8.5 ND ND
Bacillus subtilis 4.5 6.0 - 7.5 8.5
Bacillus alcalophilus 8.5 10.6 11.5
Fungi
Mucor glomerula 3.2 ND 9.2
Aspergillus terrícola 1.6 ND 9.3
Aspergillus italicum 1.9 ND 9.3
Penicillium italicum 1.9 ND 9.3
Penicillium variabile 1.6 ND 11.1
Fusarium bullatum 2.0 ND 11.2
ND : Non determined
Table 1. Several examples of pH ranges for bacteria and fungi 10 growth.
Temperature
Temperature is one of the most important environmental factors, and
can drastically affect the growth and survival of organisms. In general,
as temperatures rise, enzymatic reaction in the cell accelerates and
cellular growth is more rapid. Every micro-organism has a minimum
temperature below which growth is not possible, a optimal
temperature, at which growth is faster, and finally, a maximum
temperature, above no growth occurs. These three temperatures are
often named “cardinal temperatures” and they are characteristic for
each species. According to their optimal temperature, it is possible to
distinguish four main groups of micro-organisms :
1 Psychrophiles: with a low-temperature optima (around 15ºC). They can
grow at 0ºC but not at temperatures above 20ºC.
2 Facultative psychrophiles: they can grow at low temperatures, but
their optimum temperature is 20 - 30º C.
3 Mesophiles: with mid-range optimum temperature, usually 25 - 35 ºC,
and
4 Thermophiles: with a high optimum temperature of growth, usually
around 55 - 65ºC. These micro-organisms cannot grow below 45ºC.
Oxygen concentration
Micro-organisms vary in both their need for, and their tolerance of,
oxygen. They can be divided in three main groups:
1 Strict anaerobes: which are killed by oxygen and do not use this gas in
metabolism.
2 Facultative anaerobes: which can tolerate oxygen but cannot use it in
their metabolism and
3 Aerobes: with oxygenic respiration as their catabolic metabolism,
using oxygen as the terminal electron acceptor in respiration.
42 Journal of Film Preservation / 67 / 2004