THE APPLICATION OF FATTY-ACID METHYL-ESTER ANALYSIS (FAME) FOR THE IDENTIFICATION OF HETEROTROPHIC BACTERIA PRESENT IN DECAYING LEDE-STONE OF THE ST-BAVO-CATHEDRAL IN GHENT

The heterotrophic bacterial community present in decaying Lede-sandsto ne of the Cathedral of Ghent (Belgium) was studied. Two-hundred thirty -two heterotrophic bacterial strains were isolated of which 162 were s tudied by fatty acid methyl ester analysis (FAME). One-hundred forty i solates were Gram-positive; 101 strains belong to the genus Micrococcu s; nine strains were identified as M. kristinae. One large cluster of 83 strains was related to M. luteus/M. lylae. Other Gram-positive stra ins were related to Arthrobacter. Of the 22 Gram-negative strains, sev en strains were related to Pseudomonas vesicularis. A number of Gram-n egative and Gram-positive isolates formed separate clusters which coul d not be identified. The possible role of the bacterial isolates in st one degradation was examined by a zone-clearing test on a calcite-cont aining medium. Of the 152 strains examined, only nine showed clearing zones after 7 days of incubation at 25 degrees C, 20 odd strains showe d a dissolution of calcite after 14 days, whereas all other strains sh owed no clearing zones, even after prolonged incubation (up to 3 month s). The zone-clearing test showed the same reactions when incubated at 24 degrees C or at 19 degrees C.