Abstract
This paper aims at identification of biofilms composition taken from lime and lime-cement plasters. The samples of plasters were exposed to natural weathering for more than three years to weather conditions of Prague as a representative of Central European continental climate. After biofilms sampling, they were cultivated using specific nutrient solutions and analysed using various types of microscopes. It was found, that the plasters were covered mostly by green algae (Hematococcus pluvialis, Klebsormidium sp., Trebouxiophyceae, Chlorophyceae and Chlorellaceae), cyanobacteria (Nostoc, Anabaena, Leptolyngbya, Phormidium, Plectonema, Synechococcales and Oscillatoriale), moulds (Aspergillus niger, Alternaria) and moss (Ceratodon purpureus). Possible influence of these organisms on hygrothermal behaviour of the base materials is subsequently discussed.
Highlights
Biodegradation is an undesirable process that can affect the aesthetical, and physical and chemical properties of building materials
H. pluvialis is usually found on sandstone, granite, marble, limestone [6] and it was recognized in urns or shallow pools formed in rock hollows which are either periodically filled with rain or supplied by water oozing from overhanging ledges [7]
Identification of biofilm composition under Central European climate was done within this research
Summary
Biodegradation is an undesirable process that can affect the aesthetical, and physical and chemical properties of building materials. While the aesthetical biodegradation can negatively affect only the building materials’ appearance, the chemical can cause for instance degradation of concrete due to the emanation of metabolites of microorganisms. The biodegradation is caused by biofilms that may cover material surfaces. The composition of biofilms differs depending on the various environmental or material actors [2]. They usually contain bacteria, fungi, algae, lichen and moss. The algae and cyanobacteria can be considered as pioneering inhabitants on surface of building materials. They need just CO2, N2 and salt minerals traces [1]. Their main role in degradation consists in their ability to etch mineral components [3], increase microcracks [4] or form coloured patinas [5]
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