Investigation of the diversity of cultivable bacteria in cave ecosystem and the effect of it's in cave surface formation

Caves are poor in nutrients and have difficult conditions for the life of living things. The survival of microorganisms living under these conditions arouses curiosity and is considered worth researching. Studies on the diversity of the caves have been going on for many years. In recent years, studies have become interesting that bacteria contribute to cave formation. In this study, it was aimed to investigate the ability of cultured bacteria to be isolated from Dupnisa Cave surface samples to produce calcium carbonate (CaCO3) and to identify these bacteria by molecular methods. Morphology and Gram characteristics of bacteria obtained from water, soil and surface samples were recorded in the study. The ability of all bacteria obtained from the cave surface formations to produce CaCO3 crystals was cultivated on the B4 medium and examined under light microscope and the days and crystal shapes of the first crystal formation were recorded. In addition, the urease enzyme capabilities of the bacteria obtained from the surface were investigated and comments were made on the contribution of these capabilities to the formation of cave surfaces. It has been determined that 68.2% of the bacteria isolated from the surface are Gram (+), 52.4% of them can produce crystals on the B4 medium and 59.6% of the bacteria that can form crystals are urease negative. It was determined that 149 different isolates isolated from Dupnisa Cave surface samples and seen to form crystals on the medium belong to Proteobacteria (53.3%), Firmicutes (32.7%) and Actinobacteria (4.7%) phyla. It was determined that Bacillus mycoides, Bacillus zhangzhouensis and Bacillus cereus species started to form crystal structures on different days on each surface. In addition, Stenotrophomonas rhizophila has been found to produce crystals of different shapes on different days on the same surface. According to the data obtained, the majority of crystal-producing bacteria in the media in the first days show urease negative characteristics. It has been emphasized that other mechanisms enabling the formation of CaCO3 besides the urease mechanism should also be investigated. In the context of our study, it has been observed that the bacteria identified in the world literature both by eroding the cave walls and by forming crystals have contributed to cave surface formations.