In this study, we investigated the biomineralization potential and diversity of the epilithic bacterial communities dwelling on the limestone statue of Saint Donatus, the oldest public monument of Cluj-Napoca city (Transylvania region, NW Romania). Their spatial distribution together with phylogenetic and metabolic diversity, as well as their capacity to precipitate calcium carbonate was evaluated by combining molecular and phenotypic fingerprinting methods with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron-microscopy analyses. The results of real-time quantitative PCR, molecular fingerprinting and community-level physiological profiling showed that diverse and abundant bacterial assemblages that differ in relation to their collection site colonized the statue. The cultivation and molecular identification procedures allowed the characterization of 79 bacterial isolates belonging to Proteobacteria (73.4%), Firmicutes (19%), and Actinobacteria (7.6%). Amongst them, the 22 strains identified as being capable of calcium carbonate precipitation were found to belong mostly to Bacillus and Pseudomonas genera. We found that bacteria acted as nucleation sites, inducing the formation of nanoscale aggregates that were shown to be principally composed of vaterite. Furthermore, we expanded the current knowledge on culturable diversity of carbonatogenic bacteria by providing evidence for biogenic vaterite/calcite formation mediated by: Pseudomonas synxantha, P. graminis, Brevibacterium iodinum, Streptomyces albidoflavus, and Stenotrophomonas chelatiphaga. Overall, this study highlights the need to evaluate the carbonatogenetic potential of all the bacterial communities present on stone artwork prior to designing an efficient conservation treatment based on biomineralization.

• Klíčová slova
• bacterial cultivation, calcite, carbonatogenesis, epilithic microbiota, limestone statue, vaterite,
• Publikační typ
• časopisecké články MeSH

Crystalline limestones (marbles) is a metamorphic rock that is widely used in the construction of buildings and in the manufacturing of statues. Along with dominant carbonates, marbles often contains carbonaceous matter resulting in a more or less grey colour. The Raman spectra of metamorphosed carbonaceous material (CM) were obtained in so-called graphitic marbles from several sites in the Bohemian Massif (Czech Republic). Frequencies of the major Raman bands and spectroscopic parameters such as O- and D-peak width and D/O intensity ratio were determined to characterize the various types of CM. Three types of Raman spectra allowed the discrimination between (1) well-ordered CM-graphite of high-grade regional metamorphosed marbles, (2) CM of contact metamorphosed marbles and (3) amorphous organic compounds as "disordered" CM of low-grade regional metamorphosed marbles. Raman microspectrometric analysis revealed the coexistence of carbonaceous particles exhibiting different degrees of graphitization within one marble sample. The structural state of the CM reflects the conditions of the contact or regional metamorphism and can be described by nondestructive Raman spectroscopy. For the first time, Raman spectra measured on reduced CM grains permitted one to distinguish marbles of different origin and propose their utilization in the provenance determination.

• MeSH
• krystalizace MeSH
• mikroskopie MeSH
• Ramanova spektroskopie metody   MeSH
• uhličitan vápenatý analýza   chemie   MeSH
• uhlík analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• uhličitan vápenatý MeSH
• uhlík MeSH