Abstract

Calcium carbonate precipitation in the natural environment is associated with a variety of factors including type species of bacteria. In this study, we investigated calcium carbonate precipitation induced by bacteria isolated from rocks of Murree Hills, Lower Himalayan region, Pakistan. Four species; Acinetobacter N1, Acinetobacter N6, Bordetella N30, and Brevundimonas N5, having ureolytic activity, were found to precipitate calcium carbonate. FTIR analysis revealed the formation of calcium carbonate crystals confirmed by comparison to synthetically produced calcium carbonate. Morphological characterization by scanning electron microscopy showed crystals formed were mostly of the irregular and polygonal shape having sharp spike-like edges. All the four strains having urease enzymatic capability to convert urea into ammonia to produce calcium carbonate crystals in higher pH due to the production of an alkaline environment. The results of our research revealed a variety of rock bacteria capable of precipitating calcium carbonate in natural environments and are expected to have a great influence on the cycling of carbonates in these environments.

摘要

自然环境中碳酸钙的沉淀与多种因素有关，包括细菌的种类。在这项研究中，我们调查了从巴基斯坦下喜马拉雅地区Murree Hills的岩石中分离出的细菌引起的碳酸钙沉淀。四种；发现具有尿素分解活性的不动杆菌N1，不动杆菌N6，博德特氏菌N30和短杆菌属N5沉淀出碳酸钙。FTIR分析表明，与合成生产的碳酸钙相比，已确认形成了碳酸钙晶体。通过扫描电子显微镜的形态学表征显示形成的晶体大部分为不规则和多边形的形状，具有锋利的穗状边缘。由于产生碱性环境，所有四个具有脲酶酶促能力的菌株均能将尿素转化为氨，从而在较高的pH下产生碳酸钙晶体。我们的研究结果表明，多种岩石细菌能够在自然环境中沉淀出碳酸钙，并且有望对这些环境中碳酸盐的循环产生重大影响。