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Environmental Microbiology

Mélanie Gerphagnon, Ramsy Agha, Dominik Martin-Creuzburg, Alexandre Bec, Fanny Perriere, Cecilia Rad-Menéndez, Claire M M Gachon, Justyna Wolinska
Chytrids are ubiquitous fungal parasites in aquatic ecosystems, infecting representatives of all major phytoplankton groups. They repack carbon from inedible phytoplankton hosts into easily ingested chytrid propagules (zoospores), rendering this carbon accessible to zooplankton. Grazing on zoospores may circumvent bottlenecks in carbon transfer imposed by the dominance of inedible or poorly nutritious phytoplankton (mycoloop). We explored qualitative aspects of the mycoloop by analyzing lipid profiles (fatty acids, sterols) of two chytrids infecting two major bloom-forming phytoplankton taxa of contrasting nutritional value: the diatom Asterionella formosa and the filamentous cyanobacterium Planktothrix agardhii...
December 3, 2018: Environmental Microbiology
Sarah P Hammarlund, Jeremy M Chacón, William R Harcombe
Species interactions and coexistence are often dependent upon environmental conditions. When two cross-feeding bacteria exchange essential nutrients, the addition of a cross-fed nutrient to the environment can release one species from its dependence on the other. Previous studies suggest that continued coexistence depends on relative growth rates: coexistence is maintained if the slower-growing species is released from its dependence on the other, but if the faster-growing species is released, the slower-growing species will be lost (a hypothesis that we call "feed the faster grower" or FFG)...
December 3, 2018: Environmental Microbiology
Viola Kurm, S Geisen, W H Gera Hol
In many studies, rare bacterial taxa have been found to increase in response to environmental changes. These changes have been proposed to contribute to the insurance of ecosystem functions. However, it has not been systematically tested if rare taxa are more likely to increase in abundance than dominant taxa. Here we study whether rare soil bacterial taxa are more likely to respond to environmental disturbances and if rare taxa are more opportunistic than dominant taxa. To test this, we applied 9 different disturbance treatments to a grassland soil and observed changes in bacterial community composition over 7 days...
December 3, 2018: Environmental Microbiology
Lucas J Stal, Henk Bolhuis, Mariana Silvia Cretoiu
Phototrophic biofilms are multispecies, self-sustaining, and largely closed microbial ecosystems. They form macroscopic structures such as microbial mats and stromatolites. These sunlight-driven consortia consist of a number of functional groups of microorganisms that recycle the elements internally. Particularly, the sulfur cycle is discussed in more detail as this is fundamental to marine benthic microbial communities and because recently exciting new insights have been obtained. The cycling of elements demands a tight tuning of the various metabolic processes and require cooperation between the different groups of microorganisms...
December 3, 2018: Environmental Microbiology
Enora Briand, Sébastien Reubrecht, Florence Mondeguer, Manoëlla Sibat, Philipp Hess, Zouher Amzil, Myriam Bormans
Freshwater cyanobacteria are known for their ability to produce bioactive compounds, some of which have been described as allelochemicals. Using a combined approach of co-cultures and analyses of metabolic profiles, we investigated chemically mediated interactions between two cyanobacterial strains, Microcystis aeruginosa PCC7806 and Planktothrix agardhii PCC7805. More precisely, we evaluated changes in growth, morphology and metabolite production and release by both interacting species. Co-culture of Microcystis with Planktothrix resulted in a reduction of the growth of Planktothrix together with a decrease of its trichome size and alterations in the morphology of its cells...
November 28, 2018: Environmental Microbiology
Jiying Li, Maria Dittrich
Despite the crucial role of polyphosphate (polyP) in aquatic environments, its metabolism in cyanobacteria responding to nutrients is poorly understood. We investigate polyP in three cyanobacteria species, specifically unicellular picocyanobacteria, under various nutritional conditions. Our experiments show that the accumulation of polyP in cyanobacteria is strongly dynamic, depending on phosphate levels and growth stages. "Overplus" uptake of phosphorus (P) during the lag phase leads to the rapid accumulation of polyP, followed by lower polyP quotas during the exponential growth stage as a result of competing "luxury" P uptake and polyP utilization to support rapid cell division...
November 26, 2018: Environmental Microbiology
Yanlin Zhao, Fang Qin, Rui Zhang, Stephen J Giovannoni, Zefeng Zhang, Jing Sun, Sen Du, Christopher Rensing
The Pelagibacterales order (SAR11) in the Alphaproteobacteria dominates marine surface bacterioplankton communities, where it plays a key role in carbon and nutrient cycling. SAR11 phages, known as pelagiphages, are among the most abundant phages in the ocean. Four pelagiphages that infect Pelagibacter HTCC1062 have been reported. Here we report 11 new pelagiphages in the Podoviridae family. Comparative genomics classified these pelagiphages into the HTVC019Pvirus genus, which includes the previously reported pelagiphages HTVC011P and HTVC019P...
November 26, 2018: Environmental Microbiology
Anna K James, Linda W Kelly, Craig E Nelson, Elizabeth G Wilbanks, Craig A Carlson
Factors that affect the respiration of organic carbon by marine bacteria can alter the extent to which the oceans act as a sink of atmospheric carbon dioxide. We designed seawater dilution experiments to assess the effect of pCO2 enrichment on heterotrophic bacterial community composition and metabolic potential in response to a pulse of phytoplankton-derived organic carbon. Experiments included treatments of elevated (1000 ppm) and low (250 ppm) pCO2 , amended with 10 μmol L-1 dissolved organic carbon from Emiliana huxleyi lysates, and were conducted using surface-seawater collected from the South Pacific Subtropical Gyre...
November 20, 2018: Environmental Microbiology
Geun Cheol Song, Hyunjoo Im, Jihye Jung, Soohyun Lee, Man-Young Jung, Sung-Keun Rhee, Choong-Min Ryu
Archaea have inhabited the earth for a long period of time, and are ubiquitously distributed in diverse environments. However, few studies have focused on the interactions of archaea with other organisms, including eukaryotes such as plants, since it is difficult to cultivate sufficient numbers of archaeal cells for analysis. In this study, we investigated the interaction between soil archaea and Arabidopsis thaliana. We demonstrate for the first time that soil archaea promote plant growth and trigger induced systemic resistance (ISR) against the necrotrophic bacterium Pectobacterium carotovorum subsp...
November 20, 2018: Environmental Microbiology
Yutong Shi, Chengqian Pan, Suoyu Cen, Leilei Fu, Xun Cao, Hong Wang, Kuiwu Wang, Bin Wu
Co-occurring microorganisms have been proved to influence the performance of each other by metabolic means in nature. Here we generated a synthetic fungal-bacterial community comprising Penicillium citrinum and Pseudomonas aeruginosa employing the previously described membrane-separated co-culture device. By applying a newly-designed molecular networking routine, new citrinin-related metabolites induced by the fungal-bacterial cross-talk were unveiled in trace amounts. A mechanically-cycled co-culture setup with external pumping forces accelerating the chemically interspecies communication was then developed to boost the production of cross-talk-induced metabolites...
November 19, 2018: Environmental Microbiology
John Paul Balmonte, Andrew Buckley, Adrienne Hoarfrost, Sherif Ghobrial, Kai Ziervogel, Andreas Teske, Carol Arnosti
The extent to which differences in microbial community structure result in variations in organic matter (OM) degradation is not well understood. Here, we tested the hypothesis that distinct marine microbial communities from North Atlantic surface and bottom waters would exhibit varying compositional succession and functional shifts in response to the same pool of complex high molecular weight (HMW-OM). We also hypothesized that microbial communities would produce a broader spectrum of enzymes upon exposure to HMW-OM, indicating a greater potential to degrade these compounds than reflected by initial enzymatic activities...
November 19, 2018: Environmental Microbiology
Sebastian Gisder, Nadine Möckel, Dorothea Eisenhardt, Elke Genersch
The health of the Western honey bee is threatened by a global epidemic of deformed wing virus (DWV) infections driven by the ectoparasitic mite Varroa destructor acting as mechanical and biological virus vector. Three different variants of DWV, DWV-A, -B, and -C exist. Virulence differences between these variants and their relation to V. destructor are still controversially discussed. We performed laboratory experiments to analyze the virulence of DWV directly isolated from crippled bees (DWVP0 ) or after one additional passage in bee pupae (DWVP1 )...
November 19, 2018: Environmental Microbiology
Daniel Berry, Wade Mace, Stephen A Rehner, Katrin Grage, Paul P Dijkwel, Carolyn A Young, Barry Scott
Peramine is a non-ribosomal peptide-derived pyrrolopyrazine (PPZ)-containing molecule with anti-insect properties. Peramine is known to be produced by fungi from genus Epichloë, which form mutualistic endophytic associations with cool-season grass hosts. Peramine biosynthesis has been proposed to require only the two-module non-ribosomal peptide synthetase (NRPS) peramine synthetase (PerA), which is encoded by the 8.3 kb gene perA, though this has not been conclusively proven. Until recently, both peramine and perA were thought to be exclusive to fungi of genus Epichloë; however, a putative perA homolog was recently identified in the genome of the insect-pathogenic fungus Metarhizium rileyi...
November 19, 2018: Environmental Microbiology
Camilla L Nesbø, Rhianna Charchuk, Stephen M J Pollo, Karen Budwill, Ilya V Kublanov, Thomas H A Haverkamp, Julia Foght
The genus Mesotoga, the only described mesophilic Thermotogae lineage, is common in mesothermic anaerobic hydrocarbon-rich environments. Besides mesophily, Mesotoga displays lineage-specific phenotypes, such as no or little H2 production and dependence on sulfur-compound reduction, which may influence its ecological role. We used comparative genomics of 18 Mesotoga strains (pairwise 16S rRNA identity > 99%) and a transcriptome of M. prima to investigate how life at moderate temperatures affects phylogeography and to interrogate the genomic features of its lineage-specific metabolism...
November 19, 2018: Environmental Microbiology
Vanessa N Bednarz, Jeroen A J M van de Water, Sophie Rabouille, Jean-François Maguer, Renaud Grover, Christine Ferrier-Pagès
Dinitrogen (N2 ) fixing bacteria (diazotrophs) are an important source of new nitrogen in oligotrophic environments and represent stable members of the microbiome in tropical corals, while information on corals from temperate oligotrophic regions is lacking. Therefore, this study provides new insights into the diversity and activity of diazotrophs associated with the temperate coral Oculina patagonica from the Mediterranean Sea by combining metabarcoding sequencing of amplicons of both the 16S rRNA and nifH genes and 15 N2 stable isotope tracer analysis to assess diazotroph-derived nitrogen (DDN) assimilation by the coral...
November 19, 2018: Environmental Microbiology
Ying Liu, David Brandt, Sonoko Ishino, Yoshizumi Ishino, Eugene V Koonin, Jörn Kalinowski, Mart Krupovic, David Prangishvili
Viruses infecting hyperthermophilic archaea of the phylum Crenarchaeota display enormous morphological and genetic diversity, and are classified into 12 families. Eight of these families include only one or two species, indicating sparse sampling of the crenarchaeal virus diversity. In an attempt to expand the crenarchaeal virome, we explored virus diversity in the acidic, hot spring Umi Jigoku in Beppu, Japan. Environmental samples were used to establish enrichment cultures under conditions favoring virus replication...
November 19, 2018: Environmental Microbiology
Da Tian, Zhongquan Jiang, Liu Jiang, Mu Su, Zheye Feng, Lin Zhang, Shimei Wang, Zhen Li, Shuijin Hu
Environmental microorganisms have been widely applied in heavy metal remediation. This study explored the mechanisms of lead tolerance between two typical filamentous fungi, A. niger and P. oxalicum. It is shown that the mechanisms of reducing Pb toxicity by these two fungi have three major pathways. The secreted oxalic acid can react with Pb (II) to form insoluble Pb minerals, primarily lead oxalate. Then, the enhanced biosorption via forming new border of cell wall prevents the transportation of Pb (II) into hypha...
November 13, 2018: Environmental Microbiology
Haichao Feng, Nan Zhang, Ruixin Fu, Yunpeng Liu, Tino Krell, Wenbin Du, Jiahui Shao, Qirong Shen, Ruifu Zhang
Chemotaxis to plant root exudates is supposed to be a prerequisite for efficient root colonization by rhizobacteria. This is a highly multifactorial process since root exudates are complex compound mixtures of which components are recognized by different chemoreceptors. Little information is available as to the key components in root exudates and their receptors that drive colonization related chemotaxis. We present here the first global assessment of this issue using the plant growth-promoting rhizobacterium (PGPR) Bacillus velezensis SQR9 (formerly B...
November 12, 2018: Environmental Microbiology
Malaika K Ebert, Rebecca E Spanner, Ronnie de Jonge, David J Smith, Jason Holthusen, Gary A Secor, Bart P H J Thomma, Melvin D Bolton
Perylenequinones are a family of structurally related polyketide fungal toxins with nearly universal toxicity. These photosensitizing compounds absorb light energy which enables them to generate reactive oxygen species that damage host cells. This potent mechanism serves as an effective weapon for plant pathogens in disease or niche establishment. The sugar beet pathogen Cercospora beticola secretes the perylenequinone cercosporin during infection. We have shown recently that the cercosporin toxin biosynthesis (CTB) gene cluster is present in several other phytopathogenic fungi, prompting the search for biosynthetic gene clusters (BGCs) of structurally similar perylenequinones in other fungi...
November 12, 2018: Environmental Microbiology
Javier Torregrosa-Crespo, Carmen Pire, Rosa María Martínez-Espinosa, Linda Bergaust
Haloarchaea are extremophiles, generally thriving at high temperatures and salt concentrations, thus with limited access to oxygen. As a strategy to maintain a respiratory metabolism, many halophilic archaea are capable of denitrification. Among them are members of the genus Haloferax, which are abundant in saline/hypersaline environments. Three reported haloarchaeal denitrifiers, Haloferax mediterranei, Haloferax denitrificans and Haloferax volcanii, were characterized with respect to their denitrification phenotype...
November 12, 2018: Environmental Microbiology
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