Oana Adriana Cuzman

Biodiversity of Phototrophic Biofilms Dwelling on Monumental Fountains

Among the stone monumental assets, artistic fountains are particularly affected by microbial colonization due to constant contact with water, giving rise to biodegradation processes related with physical–chemical and aesthetical alterations. In this paper, we make an overview of reported biodiversity of the phototrophic patina developed in various fountains of Italy and Spain. The microbial composition of four fountains (two from Florence, Italy and two from Granada, Spain) was investigated using traditional and/or molecular techniques. The results indicated many common similarities with regard the phototrophic biodiversity for all the investigated fountains. Automated ribosomal RNA intergenic spacer analysis (ARISA), a molecular fingerprint tool, was used to examine the eubacterial and cyanobacterial community for two of the investigated fountains. The principal component analysis of ARISA profiles strengthens the results obtained by traditional methods and revealed separate clusters, as a consequence of the differences of micro-environmental conditions for each fountain.

Alternative nutrient sources for biotechnological use of Sporosarcina pasteurii.

The potential use of Sporosarcina pasteurii in possible biotechnological applications on a large scale (ground improvement, consolidation of building structures and ornamental stone, or in developing bio-materials for the building industry), is based on its ability to produce high amounts of carbonate in a short period of time via urea hydrolysis. Industrial biomass production would have a low environmental impact and would be most economical if the standard growth media could be replaced with alternative nutrient sources, such as byproducts or wastes from other industries, or other low cost ingredients. The use of cost effective ingredients must guarantee ureolytic activities and growth conditions that are comparable to those resulting from the standard nutrient medium. In this work, three types of alternative media were tested for growing the ureolytic active bacteria S. pasteurii: (1) alternative nutrient sources such as industrial wastes resulting from the dairy and brewery industries, (2) fertilizer urea as an alternative urea substitute, and (3) different types of poultry manure based fertilizers as nutrient and urea substitutes. The comparison between the standard media, the nutrient alternatives and urea substitutes was possible by taking the protein concentration and nitrogen content into account. Bacterial activity was evaluated in terms of biomass changes over time (CFU, optical density, ATP measurements) and indirect estimation of the enzyme production (Nessler assay, conductivity measurement). The results revealed that some of the dairy wastes tested, such as whey and buttermilk, are potential alternative nutrients for bacterial development, while the urea fertilizer is perfectly suitable as an economical substitute for pure laboratory grade urea.

Preliminary investigation of combined laser and microwave treatment for stone biodeterioration

Abstract In this work, the potential applications of surface laser removal of biological crusts from Carrara marble artefacts and in-depth microwave selective heating for treatment of possible endolithic growths have been evaluated. The investigations were carried out on seriously deteriorated marble fragments from the monumental tombs of the English Cemetery in Florence, Italy. The second harmonic (532 nm) of a Q-switched Nd:YAG laser was used for cleaning while a microwave system emitting at 2.45 GHz was tested for in-depth sterilization. As is well known, microwaves are strongly absorbed by water via dipolar energy dissipation, which permits selective heating of endolithic organisms. The effects of laser and microwave treatments were characterized using scanning electron microscopy (SEM) along with chlorophyll fluorescence with pulsed amplitude modulated imaging. The latter has allowed the quantification of the impairment effects to photosystem II of epilithic phototrophic organism residues by mapping the maximum quantum yield, while the damage to endolithic growths was evaluated by means of SEM following osmium tetroxide staining of cytoplasmic lipids. The results provide an early picture of the development and application perspectives of the combined laser and microwave treatments in the conservation of biodeteriorated stone artefacts.

Sporosarcina pasteurii use in extreme alkaline conditions for recycling solid industrial wastes

The ureolytic bacteria are one of the most efficient organisms able to produce high amounts of carbonate that easily react with the free calcium ions from the environment. Sporosarcina pasteurii, a robust microbe in alkaline environments, was tested in this work for its potential use in an eco-cementation process that involves the biomediated calcite precipitation (BCP). Bacterial behavior in extreme alkaline environment (pH values of 9-13) was tested in controlled laboratory conditions and in the presence of solid industry wastes, such as Cement Kiln Dust (CKD) and Lime Kiln Dust (LKD), by evaluating the enzymatic activity and the calcite precipitation capacity. Grain consolidation potential of S. pasteurii was tested for one type of CKD mixed with ground granulated blast-furnace slag (GGBS), with possible bioclogging and biocementation applications. The results revealed the formation of stable biocalcite in the presence of CKD, with a performance depending on the pH-value and free calcium ion content. The BCP induced by S. pasteurii and the recycling of solid wastes, such as CKD with high lime content, is a promising way for different bioclogging and biocementation applications, with benefits in construction costs and reduction of environmental pollution.

Life power and art safeguard

When a works of art or a monument is completed, it actually starts a new life, a new life influenced by the overall context where this art piece will be placed and/or exhibited. It is like a newborn that starts its life adventure. The living context is not always favorable for the new entity, and different risks may occur, depending on the deterioration agents and the duration of the exposure. Weathering, pollution, and biological colonization may cause serious problems to the exposed artistic entities. Could these deterioration problems be overcome by using sustainable and natural solutions, such as the help of living/dead microorganisms or only of their metabolic products? The answer seems to be positive and quite promising, taking into account the potent features of the microorganisms, such as the minimum requirements for living, the high velocity of reproduction, the great number of the offspring and their great resistance and adaptability to adverse environmental factors. In fact, bioremediation of different degradation problems of works of art was already successfully proven (Ranalli et al., 2000, 2005; Joseph et al., 2012; Perito et al., 2013) with cleaning and consolidation treatments. One important fact must be considered when these treatments are used in outdoor conditions. This is related with the possible consequence of the biotreatment on the ecological equilibrium present already on the surfaces to be treated. The naturally occurring microorganisms are always living in a dynamic equilibrium with the surrounding environment, forming communities of usually more than one species, so the new species used for the biotreatment could integrate or disrupt this balance. Even if dead microorganisms are used, they will surely become part of the ecosystem energy flow. A biotreatment with living microorganisms at a big scale in an outdoor environment is definitely more difficult to control and understand its own behavior in time, being linked with the ecological factors. However, the using of isolated metabolic products rather than living or dead organisms are more appropriate, as they could be better controlled. The thoroughly superpower of the microorganisms, if harnessed, could improve the safeguarding of works of art. To do this, it is essential to clearly individuate the cases where it could be applied, to have deep knowledge of the biotreatment trend and mechanisms, and of course, to ensure the reproducibility in similar conditions.