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The chemicals added to paints used to prevent biofilms on structural materials, contains chemical products that in general, also have toxic effects on the environment. Plants synthesize secondary metabolites which have antimicrobial properties and that may be a sustainable alternative to traditional biocides. The antimicrobial and algaecide effect of natural compounds of vegetal origin such as isoeugenol, carvacrol and vainillic acid was evaluated in a laboratory test by the agar diffusion method and the microatmosphere technique respectively. As antimicrobials, the compounds exerted a moderate to high activity. Vanillic acid was the least effective, followed by isoeugenol, and being carvacrol the most efficient. In the case of algae, the three compounds produced a decrease in the algal growth with respect to the control. Due to these results, carvacrol and isoeugenol were incorporated separately in an exterior waterborne paint at a concentration of 2 % w/w. Samples painted with these formulations were not colonised by algae indicating that these compounds could be used as biocides in paint formulations.

Comparative assessment of atmospheric and microbiological deterioration of constructional material of a church, which is part of the Colombian cultural heritage was made using different microbiological and surface analytical techniques complemented by electron microscopy. The main constructional material of the church of Veracruz in the urban area of the city of Medellin is peridotite, an ultramafic igneous rock containing >90% of iron and magnesium minerals such as olivine and pyroxene. Assessment showed that the atmospheric characteristics in the city of Medellin are only slightly aggressive, suggesting that weathering would not be the main cause of decay of the structural material. The main microorganisms isolated from the facade of the church were heterotrophic bacteria and fungi, and phototrophic microalgae and cyanobacteria. Lichens and mosses were also found colonizing the rock. Experimental evidence suggests that deterioration of the peridotite is mainly due to acidifying bacteria and other microbial contaminants and that atmospheric factors would only play a secondary role in the decay.

An immunonoglobulin solution containing IgA, IgG and IgM was used to prevent theformation of Pseudomonas fluorescens ( P. fluorescens ) biofilms on carbonsteel and two different types of stainless steel (SS) of industrial grade. A marked inhibition ofbacterial adhesion was found when an immunoglobulin film was formed on the metal surface priorto the immersion of the sample in bacterial cultures. Microscopic techniques like scanning electronmicroscopy (SEM) and environmental scanning electron microscopy (ESEM) were used forassessing adhesion inhibition. The electrochemical behavior of the steels was evaluated by meansof potentiodynamic runs, corrosion potential vs. time evolution and linear polarization resistancetechniques applied in the presence and the absence of the immunoglobulins.

Pre and post-Columbian archeological textiles from the Southern Andean area, sheltered in Deposit 25 at La Plata Museum (Fig. 1), were analyzed by Olympus BX51optical microscopy (OM), FEI Quanta 200 scanning electron microscopy (SEM) and Leica SP5 confocal laser scanning microscopy (CLSM) with the aim of studying their biodeterioration3 . For over 120 years, these textiles have provided information to archeologists around the world, and it was through the study of many pieces that we now know in detail the characteristics of the material culture of the various groups that inhabited the territory during the national Holocene period., Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Facultad de Ciencias Veterinarias