Iron is an important influence of volcanic ash input on the evolution of deep-sea ecosystems

Volcanoes are an important link between the internal system and the surface system of the Earth, which originates from magmatic activities in the deep part of the Earth, that is, through the eruption of volcanoes to directly affect various circles in the surface layer of the Earth. As an important product of volcanic eruption, volcanic ash has a very wide range of influence, and therefore has always been a hot spot and frontier field of research in earth science. However, due to the difficulty of sampling and the lack of cross-disciplinary research, little is known about how volcanic ash inputs affect the deep-sea environment. Here, we systematically, and with a combination of geological and microbiological expertise, initiated a study of volcanic ash-affected sediments in the Kermadec Trench. It was found that in sediments also under the influence of rhyolitic volcanic ash, iron was the main factor influencing the differences in microbial communities in these deep-sea sediments. The mental test further revealed that four categories of iron functional genes significantly influenced the corresponding microbial community structure in these volcanic ash-affected sediments, namely iron acquisition-heme transport, iron acquisition-iron transport, iron acquisition-siderophore transport, and iron storage. We also mined a large number of high-quality mags from these deep-sea sediment metagenomic data, and genomic analyses revealed the presence of iron-related functional genes in the genomes of all these mags. Studies of viruses in these sediments revealed that viruses do not affect abyssal prokaryote-mediated iron cycling by directly carrying iron-related auxiliary genes, but rather regulate it by lysing associated prokaryotes involved in iron cycling. Our results provide important data and insights for a deeper understanding of microbial-mediated abyssal Fe cycling under the influence of volcanic ash.