Abstract

This study aimed to identify the bacteria which take part in the CaCO₃ precipitation on the speleothem surfaces of Dupnisa Cave. In addition, this study highlighted the CaCO₃ precipitation ability of the bacteria with negative urease activity. 150 isolates with microbial induced calcium carbonate precipitation features were selected and identified. They were belonging to Proteobacteria (53.3%), Firmicutes (32.7%) and, Actinobacteria (4.7%) phyla. The dominant bacterial species on all surface samples were Bacillus mycoides (9.3%), Bacillus zhangzhouensis (5.3%), and Serratia quinivorans (4%). Our results showed that most of the bacteria which can precipitate calcium carbonate on the B4 medium at the first 3 days, have urease negative activity. Within this study, it has been emphasized that other mechanisms enabling the precipitation of CaCO₃ besides the urease mechanism should also be investigated. EDS analyses confirmed that the crystals were predominantly composed of calcium, carbon, and oxygen. In addition, the EDS highlighted that the two strains of Bacillus mycoides, isolated from two different surfaces, produced crystals of different morphology. Our study results to the identification of the bacteria which contribute to the Dupnisa Cave walls formation. Besides, our results showed that the Dupnisa Cave is housing bacteria with biotechnological and engineering applications potentials.

摘要

本研究旨在鉴定参与Dupnisa 洞穴洞穴表面CaCO ₃沉淀的细菌。此外，该研究强调了具有负脲酶活性的细菌的CaCO ₃沉淀能力。选择并鉴定了 150 株具有微生物诱导碳酸钙沉淀特征的分离株。它们属于变形菌门(53.3%)、厚壁菌门(32.7%) 和放线菌门 (4.7%)。所有表面样品的优势菌种为蕈状芽孢杆菌(9.3%)、漳州芽孢杆菌(5.3%) 和Serratia quinivorans(4%)。我们的结果表明，大多数在前 3 天能在 B4 培养基上沉淀碳酸钙的细菌都具有脲酶阴性活性。在该研究中，已经强调除了脲酶机制之外还应该研究能够沉淀CaCO _{3 的}其他机制。EDS 分析证实晶体主要由钙、碳和氧组成。此外，EDS 还强调，两种丝状芽孢杆菌菌株，从两个不同的表面分离，产生不同形态的晶体。我们的研究结果鉴定了有助于 Dupnisa 洞穴壁形成的细菌。此外，我们的研究结果表明，Dupnisa Cave 是具有生物技术和工程应用潜力的细菌。