Abstract. The aim of this work is to explore the ability and magnitude of the temperate cyanobacterium Dolichospermum flosaquae in MICP (microbially-induced calcium carbonate precipitation). Environmentally, MICP controls the availability of calcium, carbon and phosphorus in freshwater lakes and simultaneously controls carbon exchange with the atmosphere. Cultures of flosaquae were grown in BG11 medium containing 0, 1, 1.5, 2 and 4 mg Ca²⁺ L⁻¹, as cardinal concentrations previously reported in freshwater lakes, in addition to a control culture (BG11 containing 13 mg Ca²⁺ L⁻¹). Growth (cell number, chlorophyll a, and protein content) of D. flosaquae was generally reduced by elevating calcium concentrations of the different salts used (chloride, acetate, or citrate). D. flosaquae seems able to perform MICP as carbonate alkalinity was sharply induced up to its highest level (six times that of the control) at a citrate concentration of 4 mg Ca²⁺ L⁻¹. Calcium carbonate was formed at a pre-precipitation stage as the minimum pH necessary for precipitation (8.7) has been scarcely approached under such conditions. MICP took place mostly relying on photosynthesis and respiration, but not on urease activity, as urea was not supplemented in the growth media. However, D. flosaquae exhibited strong urease specific activity in in vitro assays (four times that of the control at 4 mg Ca²⁺ citrate L⁻¹). Residual calcium exhibited its lowest value at 4 mg Ca²⁺ citrate L⁻¹, coinciding with the highest alkalinity level. Consumed calcium was increasing with chlorophyll a content, but not with increasing cell numbers. The experiments should be repeated in a future study, but in the presence of urea, to evaluate the full potential of calcium carbonate precipitation of D. flosaquae, its dynamics and impact on biogeochemical cycles of calcium, carbon and phosphorus in freshwater lakes.

中文翻译：

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蓝藻（Dolichospermum flosaquae）微生物诱导的碳酸钙沉淀（MICP）的表现和环境影响

摘要。这项工作的目的是探索在MICP（微生物诱导的碳酸钙沉淀）中温带蓝藻Dolichospermum flosaquae的能力和大小。在环境方面，MICP控制淡水湖泊中钙，碳和磷的有效性，同时控制与大气的碳交换。的培养物flosaquae在含有0,1，1.5，2和4毫克钙BG11培养基中生长²⁺ 大号^-1，作为基数浓度淡水湖先前报道，除了对照培养物（含有13 BG11毫克钙²⁺ 大号^-1）。Dosa flosaquae的生长（细胞数量，叶绿素a和蛋白质含量）通常通过提高所用不同盐（氯化物，乙酸盐或柠檬酸盐）的钙浓度来降低钙的含量。由于在4 mg Ca ²⁺  L ^-1的柠檬酸盐浓度下碳酸盐碱度被急剧诱导至最高水平（是对照水平的六倍），因此D. flosaquae似乎能够执行MICP 。碳酸钙是在预沉淀阶段形成的，因为在这种条件下几乎未达到沉淀所需的最低pH值（8.7）。MICP的发生主要取决于光合作用和呼吸作用，但不依赖于脲酶活性，因为在生长培养基中未添加尿素。但是，D。flosaquae在体外试验中表现出很强的脲酶比活性（4 mg Ca时是对照的四倍）²⁺柠檬酸盐L ^-1）。残余钙在4 mg Ca ²⁺柠檬酸盐L ^-1处表现出最低值，与最高碱度一致。消耗的钙随着叶绿素a含量的增加而增加，但不随细胞数量的增加而增加。应该在以后的研究中重复进行该实验，但是要在存在尿素的情况下，评估D. flosaquae碳酸钙沉淀的全部潜力，其动态性以及对淡水湖泊中钙，碳和磷的生物地球化学循环的影响。