Essential oils to contrast biodeterioration of the external marble of Florence Cathedral.

The search for more sustainable strategies to contrast biodeterioration of stone cultural heritage has been developing in recent years to find alternatives to synthetic biocides, since their toxicity and potential impact on the environment and health. In this study, the application of the oregano and thyme essential oils (EOs) was tested to control microbial growth on the external marble of Florence Cathedral affected by extended darkening. Before in situ application, preliminary tests were carried out to evaluate the interference of the EOs with marble (colorimetric and water absorption assays on marble specimens) and their efficacy in inhibiting marble microbiota (sensitivity test on nutrient media).

A multi-analytical approach for the study of red stains on heritage marble.

Red stains are a common discolouration on stone cultural heritage all over the world. These are very difficult to remove and little is known about the reddish pigmentation. Numerous red stains were mapped on the Baptistery of San Giovanni in Florence, one of the most important monuments in Italy.

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.

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.

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.