Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, California, USA.
School of Chemistry and Biochemistry, School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA.
mBio. 2019 May 14;10(3):e00821-19. doi: 10.1128/mBio.00821-19.
Marine sponges are recognized as valuable sources of bioactive metabolites and renowned as petri dishes of the sea, providing specialized niches for many symbiotic microorganisms. Sponges of the family are well documented to be chemically talented, often containing high levels of polyhalogenated compounds, terpenoids, peptides, and other classes of bioactive small molecules. This group of tropical sponges hosts a high abundance of an uncultured filamentous cyanobacterium, Here, we report the comparative genomic analyses of two phylogenetically distinct populations, which reveal shared deficiencies in essential pathways, hinting at possible reasons for their uncultivable status, as well as differing biosynthetic machinery for the production of specialized metabolites. One symbiont population contains clustered genes for expanded polybrominated diphenylether (PBDE) biosynthesis, while the other instead harbors a unique gene cluster for the biosynthesis of the dysinosin nonribosomal peptides. The hybrid sequencing and assembly approach utilized here allows, for the first time, a comprehensive look into the genomes of these elusive sponge symbionts. Natural products provide the inspiration for most clinical drugs. With the rise in antibiotic resistance, it is imperative to discover new sources of chemical diversity. Bacteria living in symbiosis with marine invertebrates have emerged as an untapped source of natural chemistry. While symbiotic bacteria are often recalcitrant to growth in the lab, advances in metagenomic sequencing and assembly now make it possible to access their genetic blueprint. A cell enrichment procedure, combined with a hybrid sequencing and assembly approach, enabled detailed genomic analysis of uncultivated cyanobacterial symbiont populations in two chemically rich tropical marine sponges. These population genomes reveal a wealth of secondary metabolism potential as well as possible reasons for historical difficulties in their cultivation.
海洋海绵被认为是生物活性代谢物的有价值来源，被誉为海洋的培养皿，为许多共生微生物提供了专门的小生境。已充分证明属于 的海绵在化学上具有天赋，通常含有高水平的多卤代化合物、萜类化合物、肽和其他类别的生物活性小分子。这组热带海绵宿主大量未培养的丝状蓝细菌，。在这里，我们报告了两个系统发育上不同的 种群的比较基因组分析，这些分析揭示了它们不可培养状态的可能原因，以及产生特殊代谢物的不同生物合成机制，这些原因存在共同的必需途径缺陷。一个共生种群含有扩展的多溴二苯醚（PBDE）生物合成的聚类基因，而另一个种群则拥有独特的用于非核糖体肽合成的基因簇。这里使用的混合测序和组装方法首次允许全面观察这些难以捉摸的海绵共生体的基因组。天然产物为大多数临床药物提供了灵感。随着抗生素耐药性的增加，发现新的化学多样性来源至关重要。与海洋无脊椎动物共生的细菌已成为天然化学的未开发来源。虽然共生细菌在实验室中往往难以生长，但宏基因组测序和组装的进展现在使得获取它们的遗传蓝图成为可能。细胞富集程序与混合测序和组装方法相结合，使对两种化学丰富的热带海洋海绵中的未培养蓝细菌共生体种群进行详细的基因组分析成为可能。这些群体基因组揭示了丰富的次生代谢潜力以及历史上培养困难的可能原因。
