A team of researchers from the University of Granada, led by the professor of the Department of Painting Fernando Bolívar, works on the identification of microalgae that proliferate, above all, in monumental fountains of the Alhambra and the Generalife.
These microorganisms are colonizers that grow in stone structures causing physical, aesthetic and chemical alterations. Microalgae stain the stone of the monumental fountains, they retain water that deteriorates the substrate and its excessive growth can obstruct the passage of the water itself.
“They even favor the formation of other organisms that are more harmful to the monumental fountains like fungi or mosses ”, explains the researcher Fernando Bolivar.
Identification of microalgae
The monumental complex of the Alhambra and the Generalife, a UNESCO World Heritage Site since 1984, contains countless fountains, pools or canals that are subjected to colonization by microalgae despite the physical and chemical methods used against them. .
They even favor the formation of other organisms more harmful to monumental sources such as fungi or mosses.
From the point of view of heritage conservation, it is very useful to know the structure and functioning of the biofilms or tapestries of bacteria that form the microalgae on the stone.
Scientists study which species make up these biofilms, which are the most resistant and harmful and which conditions favor their growth. In this way, efficient methods can be designed to stop their proliferation.
“With our work we intend to make an update of the most common types of algae that are currently found in the sources of the Alhambra and the Generalife and also begin the creation of a bank of algae from crops of these species ”, Bolívar details. The derived cultures can be used in subsequent studies on new treatments against biodeterioration.
Scope of the study
The study was carried out with 120 samples of algae of 21 different fountains of the Alhambra and the Generalife. Most of the shots have been obtained in the Nasrid Palaces, due to their great cultural importance, but sources from other areas have also been selected to make a general evaluation of the most common microalgae in the entire monumental complex.
The scheduled seasonal samplings have made it possible to obtain shots of the surfaces of the selected sources, of environments submerged in water, aerial or in areas with intermittent presence of water, such as splashes. From these samples, the types of microalgae have been identified and the cultures made.
The algal communities in the samples are complex and are made up of different species
The algae present in the Alhambra correspond fundamentally to three large groups: green algae, cyanobacteria and diatoms, the last group being the least frequent.
In general, the algal communities in the samples are complex and made up of different species. In cases where the biofilms attached to the sources are composed of a single type of algae, this is usually a single-celled green algae.
Field work and sampling. / UGR
“This could be indicating that this type of algae are more resistant to the treatments currently used in the sources, such as chlorine and algaecides, or also that they are the first stone settlers”, The researchers explain.
No specific genera of algae have been observed in a given environment, nor large changes in the most frequent genera between different seasons of the year. The composition of the communities is maintained over time, although with some variations, and the genders are usually the same.
Comparing the results of this study with research carried out previously in the Alhambra it is observed how a large number of species had already been registered previously, so there have been no major changes over time.
“However, it seems that in the past there were a greater number of microalgae in the Alhambra, which can be justified by the attention currently paid to these organisms and because the sources are more strictly maintained”, clarifies the researcher from the UGR Fernando Bolívar.
The cultures will be used to carry out multiple trials in the future, such as the development of new treatments to combat the proliferation of microalgae.
The genres present in the Alhambra are also found in other sources studied in Spain and Italy and on other types of stone monuments around the world. Therefore, the species of the Granada monument are cosmopolitan, with a wide distribution, and common in stone monuments in general.
Laboratory work to combat colonization by microalgae
Along with the identification of the genera, scientists have developed cultures in the laboratory to obtain unyalgal samples, that is, made up of a single species of algae. These cultures are carried out in Petri dishes on solidified agar and kept in chambers at a certain temperature and with a light-dark cycle suitable for growth.
The cultures will serve to carry out multiple tests in the future, such as the development of new treatments to combat the proliferation of microalgae or the study of these organisms as a source of pigments and other substances applicable to art. In fact, the research group at the University of Granada participates in various projects with these objectives. To date they have managed to isolate themselves 10 genera of green algae and 13 of cyanobacteria.
Bolívar-Galiano F, Abad-Ruiz C, Sánchez-Castillo P, Toscano M, Romero-Noguera J. Frequent Microalgae in the Fountains of the Alhambra and Generalife: Identification and Creation of a Culture Collection. Applied Sciences.
Rights: Creative Commons.