Spectrofluorometry as a tool to evaluate biocide efficiency on deteriorating rock fungi

Biodeterioration of monuments is one of the prin ipal fields of interest for researchers in the conservation of cultural heritage. Microorganisms which are living on inorganic substrate can settle and spread on and into the rock materials and cause biological damages.The aim of this study was to assay effectiveness of chemical treatment which is applied in the restoration and renovation of cultural heritage by using a fluorometric method. Because cell viability is a critical parameter for assessment of success of biocide treatments, one of the objectives of research was to find a reliable method to estimate the efficacy of chemicals on rock fungi. The fluorometry tests were performed with two isolates A18 (Trimmatostroma abietis) and J26 (Exophilia jeanselmei). The cells were treated by Alkyl benzyl dimethyl ammonium chloride (BAC) 1%. Then the cells were stained with FDA (fluorescein diacetate) and Cal AM (Calcein AM), PI (Propidium Iodide), and combinations of them. The fluorometric method was done to measure the alterations of cell viability after chemical treatment. FDA stained cells performed a strong staining under microscopic as well as fluorometric recording. After cells were incubated in presence of Cal AM, fluorescence of individual cells was measured and a weak fluorescence was observed. Fungi stained by PI were not visible in any microscopic experiment. Furthermore, the fluorometric method did not show any considerable fluorescence intensity of PI stained cells. When combination of dyes was used, stained cells had not only a low yield qualitatively and quantitatively, also the fluorescence intensity of FDA was decreased. On the contrary, when FDA was used alone, strong fluorescence intensity was shown and it could well be used for chemical treatment assays and to quantify the efficacy of the chemical treatment. FDA fluorometry is accurate, reproducible and economic in both time and materials spent