TY - JOUR A1 - Masigol, Hossein A1 - Khodaparast, Seyed Akbar A1 - Mostowfizadeh-Ghalamfarsa, Reza A1 - Rojas-Jimenez, Keilor A1 - Woodhouse, Jason Nicholas A1 - Neubauer, Darshan A1 - Grossart, Hans-Peter T1 - Taxonomical and functional diversity of Saprolegniales in Anzali lagoon, Iran JF - Aquatic Ecology N2 - Studies on the diversity, distribution and ecological role of Saprolegniales (Oomycota) in freshwater ecosystems are currently receiving attention due to a greater understanding of their role in carbon cycling in various aquatic ecosystems. In this study, we characterized several Saprolegniales species isolated from Anzali lagoon, Gilan province, Iran, using morphological and molecular methods. Four species of Saprolegnia were identified, including S. anisospora and S. diclina as first reports for Iran, as well as Achlya strains, which were closely related to A. bisexualis, A. debaryana and A. intricata. Evaluation of the ligno-, cellulo- and chitinolytic activities was performed using plate assay methods. Most of the Saprolegniales isolates were obtained in autumn, and nearly 50% of the strains showed chitinolytic and cellulolytic activities. However, only a few Saprolegniales strains showed lignolytic activities. This study has important implications for better understanding the ecological niche of oomycetes, and to differentiate them from morphologically similar, but functionally different aquatic fungi in freshwater ecosystems. KW - Achlya KW - Saprolegnia KW - aquatic ecosystems KW - carbon cycling KW - polymer degradation KW - Saprolegniaceae KW - Achlyaceae Y1 - 2020 U6 - https://doi.org/10.1007/s10452-019-09745-w SN - 1573-5125 SN - 1386-2588 VL - 54 IS - 1 SP - 323 EP - 336 PB - Springer Science CY - Dordrecht ER - TY - GEN A1 - Rojas-Jimenez, Keilor A1 - Grossart, Hans-Peter A1 - Cordes, Erik A1 - Cortés, Jorge T1 - Fungal Communities in Sediments Along a Depth Gradient in the Eastern Tropical Pacific T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Deep waters represent the largest biome on Earth and the largest ecosystem of Costa Rica. Fungi play a fundamental role in global biogeochemical cycling in marine sediments, yet, they remain little explored. We studied fungal diversity and community composition in several marine sediments from 16 locations sampled along a bathymetric gradient (from a depth of 380 to 3,474 m) in two transects of about 1,500 km length in the Eastern Tropical Pacific (ETP) of Costa Rica. Sequence analysis of the V7-V8 region of the 18S rRNA gene obtained from sediment cores revealed the presence of 787 fungal amplicon sequence variants (ASVs). On average, we detected a richness of 75 fungal ASVs per sample. Ascomycota represented the most abundant phylum with Saccharomycetes constituting the dominant class. Three ASVs accounted for ca. 63% of all fungal sequences: the yeast Metschnikowia (49.4%), Rhizophydium (6.9%), and Cladosporium (6.7%). We distinguished a cluster composed mainly by yeasts, and a second cluster by filamentous fungi, but we were unable to detect a strong effect of depth and the overlying water temperature, salinity, dissolved oxygen (DO), and pH on the composition of fungal communities. We highlight the need to understand further the ecological role of fungi in deep-sea ecosystems. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1013 KW - deep-sea KW - aquatic fungi KW - biodiversity KW - Metschnikowia KW - Costa Rica Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-482360 SN - 1866-8372 IS - 1013 ER - TY - GEN A1 - Masigol, Hossein A1 - Khodaparast, Seyed Akbar A1 - Mostowfizadeh-Ghalamfarsa, Reza A1 - Rojas-Jimenez, Keilor A1 - Woodhouse, Jason Nicholas A1 - Neubauer, Darshan A1 - Grossart, Hans-Peter T1 - Taxonomical and functional diversity of Saprolegniales in Anzali lagoon, Iran T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Studies on the diversity, distribution and ecological role of Saprolegniales (Oomycota) in freshwater ecosystems are currently receiving attention due to a greater understanding of their role in carbon cycling in various aquatic ecosystems. In this study, we characterized several Saprolegniales species isolated from Anzali lagoon, Gilan province, Iran, using morphological and molecular methods. Four species of Saprolegnia were identified, including S. anisospora and S. diclina as first reports for Iran, as well as Achlya strains, which were closely related to A. bisexualis, A. debaryana and A. intricata. Evaluation of the ligno-, cellulo- and chitinolytic activities was performed using plate assay methods. Most of the Saprolegniales isolates were obtained in autumn, and nearly 50% of the strains showed chitinolytic and cellulolytic activities. However, only a few Saprolegniales strains showed lignolytic activities. This study has important implications for better understanding the ecological niche of oomycetes, and to differentiate them from morphologically similar, but functionally different aquatic fungi in freshwater ecosystems. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1395 KW - Achlya KW - Saprolegnia KW - aquatic ecosystems KW - carbon cycling KW - polymer degradation KW - Saprolegniaceae KW - Achlyaceae Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515820 SN - 1866-8372 IS - 1 ER - TY - JOUR A1 - Rojas-Jimenez, Keilor A1 - Grossart, Hans-Peter A1 - Cordes, Erik A1 - Cortés, Jorge T1 - Fungal Communities in Sediments Along a Depth Gradient in the Eastern Tropical Pacific JF - Frontiers in Microbiology N2 - Deep waters represent the largest biome on Earth and the largest ecosystem of Costa Rica. Fungi play a fundamental role in global biogeochemical cycling in marine sediments, yet, they remain little explored. We studied fungal diversity and community composition in several marine sediments from 16 locations sampled along a bathymetric gradient (from a depth of 380 to 3,474 m) in two transects of about 1,500 km length in the Eastern Tropical Pacific (ETP) of Costa Rica. Sequence analysis of the V7-V8 region of the 18S rRNA gene obtained from sediment cores revealed the presence of 787 fungal amplicon sequence variants (ASVs). On average, we detected a richness of 75 fungal ASVs per sample. Ascomycota represented the most abundant phylum with Saccharomycetes constituting the dominant class. Three ASVs accounted for ca. 63% of all fungal sequences: the yeast Metschnikowia (49.4%), Rhizophydium (6.9%), and Cladosporium (6.7%). We distinguished a cluster composed mainly by yeasts, and a second cluster by filamentous fungi, but we were unable to detect a strong effect of depth and the overlying water temperature, salinity, dissolved oxygen (DO), and pH on the composition of fungal communities. We highlight the need to understand further the ecological role of fungi in deep-sea ecosystems. KW - deep-sea KW - aquatic fungi KW - biodiversity KW - Metschnikowia KW - Costa Rica Y1 - 2020 U6 - https://doi.org/10.3389/fmicb.2020.575207 SN - 1664-302X VL - 11 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Rojas-Jimenez, Keilor A1 - Rieck, Angelika A1 - Wurzbacher, Christian A1 - Jürgens, Klaus A1 - Labrenz, Matthias A1 - Grossart, Hans-Peter T1 - A Salinity Threshold Separating Fungal Communities in the Baltic Sea JF - Frontiers in Microbiology N2 - Salinity is a significant factor for structuring microbial communities, but little is known for aquatic fungi, particularly in the pelagic zone of brackish ecosystems. In this study, we explored the diversity and composition of fungal communities following a progressive salinity decline (from 34 to 3 PSU) along three transects of ca. 2000 km in the Baltic Sea, the world’s largest estuary. Based on 18S rRNA gene sequence analysis, we detected clear changes in fungal community composition along the salinity gradient and found significant differences in composition of fungal communities established above and below a critical value of 8 PSU. At salinities below this threshold, fungal communities resembled those from freshwater environments, with a greater abundance of Chytridiomycota, particularly of the orders Rhizophydiales, Lobulomycetales, and Gromochytriales. At salinities above 8 PSU, communities were more similar to those from marine environments and, depending on the season, were dominated by a strain of the LKM11 group (Cryptomycota) or by members of Ascomycota and Basidiomycota. Our results highlight salinity as an important environmental driver also for pelagic fungi, and thus should be taken into account to better understand fungal diversity and ecological function in the aquatic realm. KW - fungal diversity KW - baltic sea KW - salinity gradient KW - brackish waters KW - chytridiomycota KW - cryptomycota Y1 - 2019 U6 - https://doi.org/10.3389/fmicb.2019.00680 SN - 1664-302X VL - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Perkins, Anita K. A1 - Ganzert, Lars A1 - Rojas-Jimenez, Keilor A1 - Fonvielle, Jeremy Andre A1 - Hose, Grant C. A1 - Grossart, Hans-Peter T1 - Highly diverse fungal communities in carbon-rich aquifers of two contrasting lakes in Northeast Germany JF - Fungal ecology N2 - Fungi are an important component of microbial communities and are well known for their ability to decompose refractory, highly polymeric organic matter. In soils and aquatic systems, fungi play an important role in carbon processing, however, their diversity, community structure and function as well as ecological role, particularly in groundwater, are poorly studied. The aim of this study was to examine the fungal community composition, diversity and function in groundwater from 16 boreholes located in the vicinity of two lakes in NE Germany that are characterized by contrasting trophic status. The analysis of 28S rRNA gene sequences amplified from the groundwater revealed high fungal diversity arid clear differences in community structure between the aquifers. Most sequences were assigned to Ascomycota and Basidiomycota, but members of Chytridiomycota, Cryptomycota, Zygomycota, Blastocladiomycota, Glomeromycota and Neocallimastigomycota were also detected. In addition, 27 species of fungi were successfully isolated from the groundwater samples and tested for their ability to decompose complex organic polymers - the predominant carbon source in the groundwater. Most isolates showed positive activities for at least one of the tested polymer types, with three strains, belonging to the genera Gibberella, Isaria and Cadophora, able to decompose all tested substrates. Our results highlight the high diversity of fungi in groundwater, and point to their important ecological role in breaking down highly polymeric organic matter in these isolated microbial habitats. (C) 2019 Elsevier Ltd and British Mycological Society. All rights reserved. KW - Groundwater KW - Aquatic fungi KW - DOC KW - CDOM KW - Aquifers KW - Humic acids Y1 - 2019 U6 - https://doi.org/10.1016/j.funeco.2019.04.004 SN - 1754-5048 SN - 1878-0083 VL - 41 SP - 116 EP - 125 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Rojas-Jimenez, Keilor A1 - Rieck, Angelika A1 - Wurzbacher, Christian A1 - Jürgens, Klaus A1 - Labrenz, Matthias A1 - Grossart, Hans-Peter T1 - A Salinity Threshold Separating Fungal Communities in the Baltic Sea T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - Salinity is a significant factor for structuring microbial communities, but little is known for aquatic fungi, particularly in the pelagic zone of brackish ecosystems. In this study, we explored the diversity and composition of fungal communities following a progressive salinity decline (from 34 to 3 PSU) along three transects of ca. 2000 km in the Baltic Sea, the world’s largest estuary. Based on 18S rRNA gene sequence analysis, we detected clear changes in fungal community composition along the salinity gradient and found significant differences in composition of fungal communities established above and below a critical value of 8 PSU. At salinities below this threshold, fungal communities resembled those from freshwater environments, with a greater abundance of Chytridiomycota, particularly of the orders Rhizophydiales, Lobulomycetales, and Gromochytriales. At salinities above 8 PSU, communities were more similar to those from marine environments and, depending on the season, were dominated by a strain of the LKM11 group (Cryptomycota) or by members of Ascomycota and Basidiomycota. Our results highlight salinity as an important environmental driver also for pelagic fungi, and thus should be taken into account to better understand fungal diversity and ecological function in the aquatic realm. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 739 KW - fungal diversity KW - baltic sea KW - salinity gradient KW - brackish waters KW - chytridiomycota KW - cryptomycota Y1 - 1019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-434937 SN - 1866-8372 IS - 739 ER - TY - JOUR A1 - Arias-Andres, Maria A1 - Rojas-Jimenez, Keilor A1 - Grossart, Hans-Peter T1 - Collateral effects of microplastic pollution on aquatic microorganisms BT - An ecological perspective JF - Trends in Analytical Chemistry N2 - Microplastics (MP) provide a unique and extensive surface for microbial colonization in aquatic ecosystems. The formation of microorganism-microplastic complexes, such as biofilms, maximizes the degradation of organic matter and horizontal gene transfer. In this context, MP affect the structure and function of microbial communities, which in turn render the physical and chemical fate of MP. This new paradigm generates challenges for microbiology, ecology, and ecotoxicology. Dispersal of MP is concomitant with that of their associated microorganisms and their mobile genetic elements, including antibiotic resistance genes, islands of pathogenicity, and diverse metabolic pathways. Functional changes in aquatic microbiomes can alter carbon metabolism and food webs, with unknown consequences on higher organisms or human microbiomes and hence health. Here, we examine a variety of effects of MP pollution from the microbial ecology perspective, whose repercussions on aquatic ecosystems begin to be unraveled. (C) 2018 Elsevier B.V. All rights reserved. KW - Microplastics (MP) KW - Biofilms KW - HGT KW - Microbial ecology KW - Carbon cycling KW - Aquatic ecosystems KW - Health risk assessment Y1 - 2018 U6 - https://doi.org/10.1016/j.trac.2018.11.041 SN - 0165-9936 SN - 1879-3142 VL - 112 SP - 234 EP - 240 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Arias-Andres, Maria A1 - Kluemper, Uli A1 - Rojas-Jimenez, Keilor A1 - Grossart, Hans-Peter T1 - Microplastic pollution increases gene exchange in aquatic ecosystems JF - Environmental pollution N2 - Pollution by microplastics in aquatic ecosystems is accumulating at an unprecedented scale, emerging as a new surface for biofilm formation and gene exchange. In this study, we determined the permissiveness of aquatic bacteria towards a model antibiotic resistance plasmid, comparing communities that form biofilms on microplastics vs. those that are free-living. We used an exogenous and red-fluorescent E. coli donor strain to introduce the green-fluorescent broad-host-range plasmid pKJKS which encodes for trimethoprim resistance. We demonstrate an increased frequency of plasmid transfer in bacteria associated with microplastics compared to bacteria that are free-living or in natural aggregates. Moreover, comparison of communities grown on polycarbonate filters showed that increased gene exchange occurs in a broad range of phylogenetically-diverse bacteria. Our results indicate horizontal gene transfer in this habitat could distinctly affect the ecology of aquatic microbial communities on a global scale. The spread of antibiotic resistance through microplastics could also have profound consequences for the evolution of aquatic bacteria and poses a neglected hazard for human health. KW - Microplastics KW - Aquatic ecosystems KW - Biofilm KW - Horizontal gene transfer KW - Antibiotic resistance Y1 - 2018 U6 - https://doi.org/10.1016/j.envpol.2018.02.058 SN - 0269-7491 SN - 1873-6424 VL - 237 SP - 253 EP - 261 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Van den Wyngaert, Silke A1 - Rojas-Jimenez, Keilor A1 - Seto, Kensuke A1 - Kagami, Maiko A1 - Grossart, Hans-Peter T1 - Diversity and Hidden Host Specificity of Chytrids Infecting Colonial Volvocacean Algae JF - Journal of Eukaryotic Microbiology N2 - Chytrids are zoosporic fungi that play an important, but yet understudied, ecological role in aquatic ecosystems. Many chytrid species have been morphologically described as parasites on phytoplankton. However, the majority of them have rarely been isolated and lack DNA sequence data. In this study we isolated and cultivated three parasitic chytrids, infecting a common volvocacean host species, Yamagishiella unicocca. To identify the chytrids, we characterized morphology and life cycle, and analyzed phylogenetic relationships based on 18S and 28S rDNA genes. Host range and specificity of the chytrids was determined by cross-infection assays with host strains, characterized by rbcL and ITS markers. We were able to confirm the identity of two chytrid strains as Endocoenobium eudorinae Ingold and Dangeardia mamillata Schroder and described the third chytrid strain as Algomyces stechlinensis gen. et sp. nov. The three chytrids were assigned to novel and phylogenetically distant clades within the phylum Chytridiomycota, each exhibiting different host specificities. By integrating morphological and molecular data of both the parasitic chytrids and their respective host species, we unveiled cryptic host-parasite associations. This study highlights that a high prevalence of (pseudo)cryptic diversity requires molecular characterization of both phytoplankton host and parasitic chytrid to accurately identify and compare host range and specificity, and to study phytoplankton-chytrid interactions in general. KW - Chytridiomycota KW - Dangeardia mamillata KW - Endocoenobium eudorinae KW - fungal parasites KW - life cycle KW - phytoplankton Y1 - 2018 U6 - https://doi.org/10.1111/jeu.12632 SN - 1066-5234 SN - 1550-7408 VL - 65 IS - 6 SP - 870 EP - 881 PB - Wiley CY - Hoboken ER -