Caldalkalibacillus thermarum TA2.A1 Genome sequencing and assembly

The aerobic thermoalkaliphile Caldalkalibacillus thermarum TA2.A1 is a phylogenetically deeply rooted member of the Bacilli class. Efforts to relate the genomic information of this evolutionary ancient organism to environmental adaptation have been thwarted by the inability to construct a complete genome. The existing draft is highly fragmented due to repetitive regions, and gaps between and over repetitive regions were unbridgeable. To address this, Oxford Nanopore Technology MinION allowed us to span these repeats through long reads, with over 6000-fold coverage. This resulted in a single 3.34 Mb circular chromosome

需氧嗜热嗜碱菌卡尔碱芽孢杆菌（Caldalkalibacillus thermarum）TA2.A1是芽孢杆菌纲（Bacilli）中系统发育地位极深的演化类群成员。此前，将这一演化古老物种的基因组信息与其环境适应性相关联的研究因无法获取完整基因组而一度受阻。现有基因组草图因存在大量重复序列区域而高度碎片化，且重复序列区域间及内部的间隙均无法填补。为解决这一问题，我们借助牛津纳米孔科技（Oxford Nanopore Technology）MinION测序平台，通过长读长测序覆盖这些重复序列，最终获得了超过6000倍的测序覆盖度，并成功得到一条长度为3.34 Mb的环状染色体。