Background Synechococcus sp. PCC 7002 is an attractive organism as a feedstock and for photoautotrophic production of biofuels and biochemicals due to its fast growth and ability to grow in marine/brackish medium. Previous studies suggest that the growth of this organism is limited by the HCO3 - transport across the cytoplasmic membrane. Tools for genetic engineering are well established for this cyanobacterium, which makes it possible to overexpress genes of interest. Results In this work, we overexpressed two different native Na+-dependent carbon transporters viz., SbtA and BicA in Synechococcus sp. PCC 7002 cells under the influence of a strong light-inducible promoter and a strong RBS sequence. The overexpression of these transporters enhanced biomass by about 50%, increased intracellular glycogen about 50%, and increased extracellular carbohydrate up to threefold. Importantly, the biomass and glycogen productivity of the transformants with air bubbling was even higher than that of WT cells with 1% CO2 bubbling. The overexpression of these transporters was associated with an increased carotenoid content without altering the chl a content. Conclusions Our work shows the utility of increased carbon transport in improving the growth as well as product formation in a marine cyanobacterium and will serve to increase the utility of this organism as a potential cell factory.

中文翻译：

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海洋蓝藻聚球藻中碳酸氢盐转运蛋白的过度表达。PCC 7002 增加生长速度和糖原积累。

背景 Synechococcus sp. PCC 7002 是一种有吸引力的有机体，可作为原料和光合自养生产生物燃料和生化产品，因为它的快速生长和在海洋/半咸水培养基中生长的能力。以前的研究表明，这种生物体的生长受到 HCO3 的限制 - 跨细胞质膜的运输。对于这种蓝藻，基因工程工具已经很好地建立起来，这使得过度表达感兴趣的基因成为可能。结果在这项工作中，我们在 Synechococcus sp 中过表达了两种不同的天然 Na+ 依赖性碳转运蛋白，即 SbtA 和 BicA。在强光诱导启动子和强 RBS 序列影响下的 PCC 7002 细胞。这些转运蛋白的过表达使生物量增加了约 50%，细胞内糖原增加了约 50%，细胞外碳水化合物增加了三倍。重要的是，具有气泡的转化体的生物量和糖原生产力甚至高于具有 1% CO2 鼓泡的 WT 细胞。这些转运蛋白的过度表达与类胡萝卜素含量的增加有关，而不会改变叶绿素 a 的含量。结论 我们的工作表明增加碳运输在改善海洋蓝藻的生长和产物形成方面的效用，并将有助于增加这种生物体作为潜在细胞工厂的效用。这些转运蛋白的过度表达与类胡萝卜素含量的增加有关，而不会改变叶绿素 a 的含量。结论 我们的工作表明增加碳运输在改善海洋蓝藻的生长和产物形成方面的效用，并将有助于增加这种生物体作为潜在细胞工厂的效用。这些转运蛋白的过度表达与类胡萝卜素含量的增加有关，而不会改变叶绿素 a 的含量。结论 我们的工作表明增加碳运输在改善海洋蓝藻的生长和产物形成方面的效用，并将有助于增加这种生物体作为潜在细胞工厂的效用。