Biological risk assessment in the History and Historical Documentation Library of the University of Milan.

There are billions of books that in recent and in ancient times have been produced by the human race containing evidence of its intellectual and cultural efforts. Even when stored in libraries, not all these books survive over time undamaged, because in the biosphere their materials are potential nutrients. This is the unfortunate case of the History and Historical Documentation Library of the University of Milan, where biological agents have badly affected rare and valuable old books. An entomological monitoring was carried out using sticky traps and collecting insects during inspections. The beetle Gastrallus pubens Fairmaire, rarely identified in European libraries so far, was the main biological agent responsible for the book damage, since several tunnels due to larval activity and holes made by adults were observed. Using the Illumina MiSeq sequencing technology, Proteobacteria, Firmicutes and Actinobacteria were found to be the most abundant phyla. Ascomycota was the dominant phylum among three fungal phyla. As bacteria and fungi spread by the insects are primary indications of the insect presence in the library, in this paper a potential biomarker able to detect the G. pubens presence before visible infestation was searched for among the bacterial and fungal community peculiar in the insect frass and gut, but also found on books and the surfaces of shelves. Symbiotaphrina, an ascomycete fungus described as one of the symbiotic levuliform fungi, present in the anobiid beetles' gut, was the only one found in all samples analyzed and has therefore been proposed as a putative biomarker.

Bioremoval of graffiti using novel commercial strains of bacteria.

Previous studies have provided evidence that bioremediation deals a novel approach to graffiti removal, thereby overcoming well-known limitations of current cleaning methods. In the present study eight bacteria aerobic, mesophilic and culturable from the American ATCC and the German DSMZ collections of microorganisms, some isolated from car paint waste, colored deposits in a pulp dryer and wastewater from dye works, were tested in the removal of silver and black graffiti spray paints using immersion strategies with glass slides. Absorbance at 600 nm and live/dead assays were performed to estimate bacterial density and activity in all samples. Also, pH and dissolved organic carbon (DOC) and inorganic carbon (DIC) measurements in the liquid media were made, as well as, thickness, colorimetric and infrared (FTIR) spectroscopy measurements in graffiti paint layers were used to evaluate the presence of the selected bacteria in the samples and the graffiti bioremoval capacity of bacteria. Data demonstrated that of the eight bacteria studied, Enterobacter aerogenes, Comamonas sp. and a mixture of Bacillus sp., Delftia lacustris, Sphingobacterium caeni, and Ochrobactrum anthropi were the most promising for bioremoval of graffiti. According to significant changes in FTIR spectra, indicating an alteration of the paint polymeric structure, coupled with the presence of a consistent quantity of live bacteria in the medium as well as a significant increase of DIC (a measure of metabolic activity) and a change in paint color.

Laboratory grown subaerial biofilms on granite: application to the study of bioreceptivity.

Simulated environmental colonisation of granite was induced under laboratory conditions in order to develop an experimental protocol for studying bioreceptivity. The experimental set-up proved suitable for producing subaerial biofilms by inoculating granite blocks with planktonic multi-species phototrophic cultures derived from natural biofilms. The ability of four different cultures to form biofilms was monitored over a three-month growth period via colour measurements, quantification of photosynthetic pigments and EPS, and CLSM observations. One of the cultures under study, which comprised several taxa including Bryophyta, Charophyta, Chlorophyta and Cyanobacteria, was particularly suitable as an inoculum, mainly because of its microbial richness, its rapid adaptability to the substratum and its high colonisation capacity. The use of this culture as an inoculum in the proposed experimental set-up to produce subaerial biofilms under laboratory conditions will contribute to standardising the protocols involved, thus enabling more objective assessment of the bioreceptivity of granite in further experiments.

Assessing the microbiological risk to stored sixteenth century parchment manuscripts: a holistic approach based on molecular and environmental studies.

The microbial risk for the conservation of seven sixteenth century parchment manuscripts, which showed brown discolouration putatively caused by microorganisms, was evaluated using non-invasive sampling techniques, microscopy, studies of surface-associated and airborne microflora with culture-independent molecular methods, and by measuring repository thermo-hygrometric values. Microscopic observations and ATP assays demonstrated a low level of contamination, indicating that the discolouration was not related to currently active microbial colonisation. Nevertheless, a culture-independent molecular approach was adopted to fully characterise surface-associated communities searching for biodeteriogens that could grow under appropriate thermo-hygrometric conditions. Indeed, potential biodeteriogens and microorganisms that are ecologically related to humans were found, suggesting the need to control the conservation environment and improve handling procedures. Microbial loads of air and thermo-hygrometric measurements showed that the repository was not suitable for preventing the microbial deterioration of parchment. A holistic approach to the assessment of risk of microbial deterioration of documents and heritage preservation is proposed for the first time.