Relevamiento microbiológico del aire y de materiales almacenados en el Archivo Histórico del Museo de La Plata, Argentina y en el Archivo Nacional de la República de Cuba

Abstract

Los objetivos del estudio fueron: determinar la microbiota del aire en el Archivo Histórico del Museo de la Plata (AHMP) y en dos depósitos del Archivo Nacional de Cuba (ANC), determinar niveles de contaminación microbiana sobre fotografías y mapas de ambos archivos, realizar la tipificación de hongos y bacterias aislados y relacionarlos con eventuales procesos patogénicos. En el análisis microbiológico del aire se empleó un método de sedimentación y para documentos, se usó el hisopado. A los hongos se les determinó actividad celulolítica, producción de pigmentos y ácidos; a las bacterias, actividad proteolítica, amilolítica y acidificante. Se obtuvieron concentraciones microbianas elevadas en los locales del ANC siendo los niveles de bacterias significativamente altos. En el AHMP los valores fueron más bajos y sólo se detectó el género fúngico Penicillium. En el ANC prevalecieron Aspergillus, Cladosporium y Penicillium. La mayoría de los hongos degradaron la celulosa, produjeron pigmentos y ácidos. De las bacterias del aire, predominaron las Gram positivas en la mayoría de los locales y se identifi caron Streptomyces, Bacillus, Streptococcus y Staphylococcus. De los documentos se aislaron los hongos Aspergillus, Penicillium y Talaromyces helicus (teleomorfo de Penicillium) que por su difícil aislamiento de objetos de arte y documentos, resulta un hallazgo novedoso. También se aislaron las bacterias Clostridium, Bacillus y Streptomyces que poseen actividad proteolítica y/o celulolítica. Algunas de las bacterias y los hongos aislados son capaces de producir enfermedades.

The objectives of the paper were: a) to determine the concentration of microbial contamination of the Achivo Histórico del Museo de La Plata (AHMP) and also the levels of microbial contamination on photos; b) to fi nd out the concentration of microbial contamination at repositories (Photographic Library and Maps Library) of the Archivo Nacional de Cuba (ANC) and to evaluate the levels of microbial contamination upon photos and maps; c) to conduct the physiological characterization of the fungi and bacteria isolated and d) to briefl y describe the pathogenic characteristics of the microorganisms identifi ed. A gravimetric method was used to perform the microbiological sampling of the air. Open Petri dishes located at approximately 2 m from the fl oor during 30 min were placed in fi ve different areas of AHMP; they contained PCA culture media for total mesophilic aerobic bacteria and YGC (Yeast extract Agar –glucose – chloramphenicol) for moulds and yeasts. Open Petri dishes were exposed at approximately 3 m from the fl oor during 5 min at repositories of ANC (in fi ve different places for the Maps Library and in two areas for the Photographic Library), the dishes contained Malt Agar + NaCl (7.5%) for the isolation of fungi and Nutrient Agar for bacteria. Later, the dishes for bacteria were incubated at 30°C for 72 hours while those for fungi were incubated at 28ºC during 7 days. A hyssop was used for collecting samples from documents. The documents analyzed were 19th century maps and photos, having paper as their main support, although there were two in silk support and a crystal slide. Fungal and bacterial concentrations at AHMP were low and they oscillated between 60 and 200 CFU/m3, hence that it is considered a NON CONTAMINATED environment. On the other hand, the concentrations at ANC were higher, ranging between 78 and 261 CFU/m3 for fungi and 639 -2149 CFU/m3 for bacteria therefore its environments are regarded as NON CONTAMINATED as to fungi, but they classify as HIGHLY CONTAMINATED in relation to bacteria. Penicillium was the only fungal species detected in the air of AHMP, while the prevailing species at ANC’s repositories were Aspergillus, Cladosporium and Penicillium. Aspergillus niger, Aspergillus fumigatus and Aspergillus fl avus were the ones that prevailed within Aspergillus genus at the repositories of ANC. Most of the environmental fungi isolated degraded cellulose and excreted pigments which comprised tones ranging from yellow to gray, including also reddish and brown hues. With respect to air bacteria, it could be detected that the number of Gram positive species was higher in two of the areas analyzed (100% at AHMP and a 92% at the Photographic Library of ANC) and among the genera identifi ed there were the following: Streptomyces, Bacillus, Streptococcus and Staphylococcus. Gram negative bacteria which prevailed at the Maps Library (77%) of ANC were also isolated; they belong to Serratia and Enterobacter genera. In relation to documents, it was determined that bacterial concentrations outnumbered fungal ones. Moreover, the total bacteria in documents with silk support were higher than those in the rest of the documents, and proteolytic bacteria prevailed in the fi rst group, while the amylolytic species were higher in the other documents. Clostridium, Bacillus and Streptomyces species were identifi ed within the bacterial genera, all of them with known proteolytic and/or cellulolytic activity. Species such as Aspergillus, Penicillium, Micelia esterilia and Talaromyces helicus (Penicillium teleomorphism) could be isolated from photos and maps. Regarding fungal teleomorphism, it is claimed that these are species hard to isolate from the surface of objects of art and documents, which turns out to be a novel fi nding in this research.