Diversity and Biomineralization Potential of the Epilithic Bacterial Communities Inhabiting the Oldest Public Stone Monument of Cluj-Napoca (Transylvania, Romania).
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 toBacillusandPseudomonasgenera. 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, andStenotrophomonas 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.
Department of Molecular Biology and Biotechnology, Babeş-Bolyai UniversityCluj-Napoca, Romania; Institute of Hydrobiology, Department of Aquatic Microbial Ecology, Biology Center of the Academy of Sciences of the Czech RepublicČeské Budějovice, Czechia.
Adrian-Ştefan
AŞ
Andrei
Department of Molecular Biology and Biotechnology, Babeş-Bolyai UniversityCluj-Napoca, Romania; Department for Internal Medicine, Medical University of GrazGraz, Austria.
Manuela R
MR
Păuşan
Department of Geology, Babeş-Bolyai University Cluj-Napoca, Romania.
Tudor
T
Tămaş
Department of Geology, Babeş-Bolyai University Cluj-Napoca, Romania.
Nicolae
N
Har
Department of Molecular Biology and Biotechnology, Babeş-Bolyai UniversityCluj-Napoca, Romania; Electron Microscopy Center, Babeş-Bolyai UniversityCluj-Napoca, Romania.
Lucian
L
Barbu-Tudoran
Faculty of Physics, Babeş-Bolyai University Cluj-Napoca, Romania.
Nicolae
N
Leopold
Department of Molecular Biology and Biotechnology, Babeş-Bolyai UniversityCluj-Napoca, Romania; Center for Systems Biology, Biodiversity, and Bioresources, Babeş-Bolyai UniversityCluj-Napoca, Romania.
Horia L
HL
Banciu
bacterial cultivation; calcite; carbonatogenesis; epilithic microbiota; limestone statue; vaterite