http://www.diva-portal.org This is the published version of a paper published in PLoS One. Citation for the original published paper (version of record): Ivarsson, M., Peckmann, J., Tehler, A., Broman, C., Bach, W. et al. (2015) Zygomycetes in Vesicular Basanites from Vesteris Seamount, Greenland Basin - A New Type of Cryptoendolithic Fungi. PLoS One, 10 http://dx.doi.org/10: e0133368 Access to the published version may require subscription. N.B. When citing this work, cite the original published paper. Permanent link to this version: http://urn.kb.se/resolve?urn=urn:nbn:se:nrm:diva-1580 RESEARCH ARTICLE Zygomycetes in Vesicular Basanites from Vesteris Seamount, Greenland Basin – A New Type of Cryptoendolithic Fungi Magnus Ivarsson1*, Jörn Peckmann2, Anders Tehler3, Curt Broman4, Wolfgang Bach5, Katharina Behrens5, Joachim Reitner6, Michael E. Böttcher7, Lena Norbäck Ivarsson8 1 Department of Palaeobiology and the Center for Earth Evolution (NordCEE), Swedish Museum of Natural History, Stockholm, Sweden, 2 Department of Geodynamics and Sedimentology, Center for Earth Sciences, University of Vienna, Vienna, Austria, 3 Department of Botany, Swedish Museum of Natural History, Stockholm, Sweden, 4 Department of Geological Sciences, Stockholm University, Svante Arrheniusväg 8, Stockholm, Sweden, 5 MARUM–Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany, 6 Geobiology Group, Geoscience Centre, Georg-August University, Göttingen, Germany, 7 Geochemistry & Isotope Biogeochemistry Group, Department for Marine Geology, Leibniz Institute for Baltic Sea Research (IOW), Warnemünde, Germany, 8 School of Natural Sciences, Technology and Environmental Studies, Södertörn University, Alfred Nobels Allé 7, Stockholm, Sweden * [email protected] OPEN ACCESS Citation: Ivarsson M, Peckmann J, Tehler A, Broman C, Bach W, Behrens K, et al. (2015) Zygomycetes in Abstract Vesicular Basanites from Vesteris Seamount, Greenland Basin – A New Type of Cryptoendolithic Fungi have been recognized as a frequent colonizer of subseafloor basalt but a substantial Fungi. PLoS ONE 10(7): e0133368. doi:10.1371/ understanding of their abundance, diversity and ecological role in this environment is still journal.pone.0133368 lacking. Here we report fossilized cryptoendolithic fungal communities represented by Editor: Jae-Hyuk Yu, The University of Wisconsin— mainly Zygomycetes and minor Ascomycetes in vesicles of dredged volcanic rocks (basa- Madison, UNITED STATES nites) from the Vesteris Seamount in the Greenland Basin. Zygomycetes had not been Received: June 5, 2015 reported from subseafloor basalt previously. Different stages in zygospore formation are Accepted: June 26, 2015 documented in the studied samples, representing a reproduction cycle. Spore structures of both Zygomycetes and Ascomycetes are mineralized by romanechite-like Mn oxide Published: July 16, 2015 phases, indicating an involvement in Mn(II) oxidation to form Mn(III,VI) oxides. Zygospores Copyright: © 2015 Ivarsson et al. This is an open still exhibit a core of carbonaceous matter due to their resistance to degradation. The fungi access article distributed under the terms of the Creative Commons Attribution License, which permits are closely associated with fossiliferous marine sediments that have been introduced into unrestricted use, distribution, and reproduction in any the vesicles. At the contact to sediment infillings, fungi produced haustoria that penetrated medium, provided the original author and source are and scavenged on the remains of fragmented marine organisms. It is most likely that such credited. marine debris is the main carbon source for fungi in shallow volcanic rocks, which favored Data Availability Statement: All relevant data are the establishment of vital colonies. within the paper. Funding: This work was funded by the Swedish Research Council (Contract No. 2012-4364), the Deutsche Forschungsgemeinschaft through project BO 1583/3, PE 847/3, RE 665/25 within priority program 1144 ‘From Mantle to Ocean: Energy-, Material- and Lifecycles at Spreading Axes’, and the Introduction Danish National Research Foundation (DNRF53). Subseafloor basaltic rocks have been recognized as an extensive microbial habitat harboring a Competing Interests: The authors have declared substantial portion of microorganisms whose abundance, diversity and ecological role is far that no competing interests exist from understood [1,2]. Phylogenetic studies are rare due to sampling issues at great depths and PLOS ONE | DOI:10.1371/journal.pone.0133368 July 16, 2015 1/16 Zygomycetes in Vesicular Basanites conditions, but show a wide diversity among bacteria and archaea from both dredged samples [3–5], and deep drilled igneous rock [6–8]. As an alternative to phylogenetic methods investi- gation of fossilized material has proven useful. A diverse fossil record ranging from ichnofossils in volcanic glass [9] to fossilized endolithic communities in veins and vesicles of basalts [10– 14] has been described. A majority of the recognized endoliths has been interpreted as fungal remains. Morphological characteristics such as repetitive septa, anastomosis, sporophores and central pores have been reported as well as chitin, a common constituent in fungal cell walls, and absent among prokaryotes [10,12,13]. Fungal colonization occurs relative early after the basalt has cooled, and prior to formation of secondary minerals like carbonates or zeolites [13,14]. Initially, the fungi cover the inner walls of the pore space with a biofilm from which hyphae and yeast structures grow and subse- quently form mycelial-like networks. Associated with mycelia, fruiting bodies, spores and rest- ing structures like sclerotia have been described, indicating that the fungi flourish in vital and sustainable colonies within the basalt [13,15]. The fungi have even been shown to exist in sym- biotic-like relationships with prokaryotes, an absolute requirement for propagation in the basalts and for long term survival of heterotrophs in an igneous rock-hosted environment [14]. The subseafloor crust as a fungal habitat challenges previous conceptions of the deep bio- sphere being predominantly an ecological niche of chemoautotrophic prokaryotes. Still, we have only a fragmentary knowledge on the subseafloor fungal communities within igneous lithologies. A wide range of investigations including phylogeny, geochemistry and paleobiol- ogy, therefore, needs to be carried out to fully understand the role fungi play in these environ- ments. Their ecological role needs to be established considering the geobiological impact fungi have in terrestrial environments, and their diversity needs to be investigated. Previously, Ivars- son et al. [12] interpreted subseafloor fungi as Ascomycetes or stem-group Dikarya. Based on morphological characteristics among zygospores, we here extend the fungal diversity to also include Zygomycetes, in dredged samples from the Vesteris Seamount in the Greenland Basin. We further show how fungi live on decomposing fragmented marine organisms from marine sediments introduced into the shallow vesicles, and also discuss Mn(II) oxidation and forma- tion of Mn(III,IV) oxides in fungal spores. Samples and Methods The samples are from the Vesteris Seamount, approximately 300 km north of the island of Jan Mayen (Fig 1) and were retrieved by TV-guided grab during expedition ARKVII/1 by RV Polarstern in June/July of 1990 [16]. The sample was not collected in a protected area and spe- cific permissions were not required for sampling. The field studies did not involve endangered or protected species. The investigated material is deposited in the collections of the Geoscience Museum of the University of Göttingen, Germany (GZG-PB.4041–4045), and accessible by the general public. Vesteris Seamount is a young singular volcanic edifice resting upon 44 Ma old basement in the >3000-m deep central Greenland Basin. Vesteris Seamount is composed of highly alkaline lavas of alkalibasaltic to basanitic/tephritic compositions, consistent with small extents of man- tle melting due to great lithospheric thickness [17]. Vesteris Seamount is volcanically active and the age of the tephritic rocks, in which the fossils are found, is 0.5 to 0.65 Ma, as deter- mined by Ar-Ar dating of kaersutite phenocrysts [18]. Video sled seafloor mapping has indi- cated very little sediment accumulation in the summit area, which is densely populated by sponges and shows evidence for spotty low-temperature hydrothermal activity [19]. The samples were collected at 73°27.43’N, 09°16.34’W and 727 m water depth [19] from the southern part of a 15 km long, crescent-shape, NE-SW trending crest developed in the summit PLOS ONE | DOI:10.1371/journal.pone.0133368 July 16, 2015 2/16 Zygomycetes in Vesicular Basanites Fig 1. Map of Vesteris seamount. (A) Map of the northwestern part of the Atlantic showing the location of Vesteris Seamount in the Greenland Basin. Image reproduced from the GEBCO world map 2014, www.gebco.net. (B) Bathymetric map of Vesteris Seamount processed using combined multibeam data from RV Polarstern expeditions ARK II/4, ARK VII/1, ARKXVIII/1, and ARK XIX/4. The location from which the samples examined in this study were taken is marked by a black square. doi:10.1371/journal.pone.0133368.g001 area of the volcano. The sample location is near the top of a steep south-facing slope leading to a lower-tiered section of the southernmost crest (Fig 1). The seafloor there is composed of scor- acious lava decorated with small