Most studies on the diversity of magnetotactic bacteria (MTB) have been conducted on samples obtained from the Northern or the Southern hemispheres. The diversity of MTB in tropical Asia near the geo-equator, with a close-to-zero geomagnetic inclination, weak magnetic field and constantly high seawater temperature has never been explored. This study aims to decipher the diversity of MTB in the marine environment of Singapore through shotgun metagenomics. Although MTB has been acknowledged to be ubiquitous in aquatic environments, we did not observe magnetotactic behaviour in the samples. However, we detected the presence and determined the diversity of MTB through bioinformatic analyses. Metagenomic analysis suggested majority of the MTB in the seafloor sediments represents novel MTB taxa that cannot be classified at the species level. The relative abundance of MTB (∼0.2-1.69%) in the samples collected from the marine environment of Singapore was found to be substantially lower than studies for other regions. In contrast to other studies, the genera Magnetovibrio and Desulfamplus, but not Magnetococcus, were the dominant MTB. Additionally, we recovered 3 MTB genomic bins that are unclassified at the species level, with Magnetovibrio blakemorei being the closest-associated genome. All the recovered genomic bins contain homologs of at least 5 of the 7 mam genes but lack homologs for mamI, a membrane protein suggested to take part in the magenetosome invagination. This study fills in the knowledge gap of MTB biodiversity in the tropical marine environment near the geo-equator. Our findings will facilitate future research efforts aiming to unravel the ecological roles of MTB in the tropical marine environments as well as to bioprospecting novel MTB that have been adapted to tropical marine environments for biotechnological applications.

关于趋磁细菌（MTB）多样性的大多数研究都是在从北半球或南半球获得的样品上进行的。从未探索过地球赤道附近热带亚洲的MTB多样性，地磁倾角接近零，磁场弱以及海水温度持续升高。这项研究旨在通过散弹枪宏基因组学来解读新加坡海洋环境中山地自行车的多样性。尽管已经公认MTB在水生环境中无处不在，但我们并未在样品中观察到趋磁行为。但是，我们通过生物信息学分析检测了MTB的存在并确定了MTB的多样性。元基因组学分析表明，海底沉积物中的大多数MTB代表了无法在物种一级分类的新颖MTB分类群。从新加坡海洋环境收集的样品中，MTB的相对丰度（〜0.2-1.69％）被发现大大低于其他地区的研究。与其他研究相反，属磁链球菌和脱硫氨纶（而非磁球菌）是主要的MTB。此外，我们回收了3个在物种水平上未分类的MTB基因组区域，其中Magnetovibrio blakemorei是最接近的基因组。所有回收的基因组箱包含7个至少5的同系物MAM基因，但缺乏同源的真身，这是一种膜蛋白，提示其参与了基因组体的内陷。这项研究填补了地球赤道附近热带海洋环境中山地生物多样性的知识空白。我们的发现将有助于未来的研究工作，旨在揭示MTB在热带海洋环境中的生态作用，以及对已经适应热带海洋环境进行生物技术应用的新型MTB进行生物勘探。