Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, SBS-01N-27, 637551, Singapore.
Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, SBS-01N-27, 637551, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Ave, N1-01C-69, 639798, Singapore.
Environ Res. 2021 Mar;194:110714. doi: 10.1016/j.envres.2021.110714. Epub 2021 Jan 8.
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.
大多数关于磁细菌（MTB）多样性的研究都是在北半球或南半球采集的样本上进行的。赤道附近热带亚洲的 MTB 多样性，地磁倾角接近零，磁场较弱，海水温度始终很高，从未被探索过。本研究旨在通过鸟枪法宏基因组学来破译新加坡海洋环境中的 MTB 多样性。尽管 MTB 已被公认为在水生环境中无处不在，但我们在样本中没有观察到磁行为。然而，我们通过生物信息学分析检测到了 MTB 的存在和多样性。宏基因组分析表明，海底沉积物中的大多数 MTB 代表了新型的 MTB 分类群，无法在物种水平上进行分类。在从新加坡海洋环境中采集的样本中，MTB 的相对丰度（约 0.2-1.69%）明显低于其他地区的研究。与其他研究相反，属 Magnetovibrio 和 Desulfamplus，但不是 Magnetococcus，是主要的 MTB。此外，我们还回收了 3 个未分类到物种水平的 MTB 基因组框，其中 Magnetovibrio blakemorei 是最接近的相关基因组。所有回收的基因组框都至少包含 7 个 mam 基因中的 5 个同源物，但缺乏mamI 同源物，mamI 是一种被认为参与磁小体内陷的膜蛋白。本研究填补了赤道附近热带海洋环境中 MTB 生物多样性的知识空白。我们的发现将有助于未来的研究努力，旨在揭示 MTB 在热带海洋环境中的生态作用，并为生物技术应用生物勘探适应热带海洋环境的新型 MTB。
