SFS Annual Meeting

5/21/2018  |   14:00 - 14:15   |  330 A

A GUT FEELING: THE EFFECTS OF LEAF LITTER TYPE ON THE ACTIVE MICROBIOME OF A SHREDDING CADDISFLY Insect gut microbes facilitate the digestion of plant material supporting the idea that the gut microbiome is a crucial component in freshwater detritivores. We used quantitative stable isotope probing (qSIP), a molecular method which differentiates actively growing microbes from inactive microbes to investigate the gut microbiome of a detritivore shredder, Hesperophlax magnus. qSIP allowed us to tease apart “transient microbes” (i.e., those passing through the gut) from “facilitative microbes” (i.e., gut residents). We conducted a laboratory mesocosm experiment in which two different leaf species were conditioned for ten days, colonizing with their respective microbial communities. Shredders then fed on the conditioned leaves for four days and afterwards, were placed in ¹⁸O labeled water for 2-5 days. Growing microbial cells in the gut incorporated the ¹⁸O label. By measuring this isotopic label and sequencing the newly labeled DNA of gut microbes, we quantified growth, thereby distinguishing organisms that were active in the gut from inactive microbes that were ingested. In this talk we demonstrate how qSIP can be used to estimate taxon-specific growth rates of bacteria in the microbiome of shredding insects.

Rebecca Fritz (Co-Presenter/Co-Author), Northern Arizona University, rjf227@nau.edu;


Benjamin Koch (Primary Presenter/Author), Northern Arizona University, ben.koch@nau.edu;


Michaela Hayer (Co-Presenter/Co-Author), Northern Arizona University, michaela.hayer@nau.edu;


Bruce Hungate (Co-Presenter/Co-Author), Northern Arizona University, bruce.hungate@nau.edu;


Jane Marks (Co-Presenter/Co-Author), Northern Arizona University, jane.marks@nau.edu;


Egbert Schwartz (Co-Presenter/Co-Author), Northern Arizona University, egbert.schwartz@nau.edu;


Presentation:
This presentation has not yet been uploaded.

5/21/2018  |   14:15 - 14:30   |  330 A

BACTERIAL AND FUNGAL SPECIES RESPOND DIFFERENTLY TO LEAF LITTER TYPE: APPLICATIONS OF QUANTITATIVE STABLE ISOTOPE PROBING (QSIP) Quantitative stable isotope probing (qSIP) combined with high throughput sequencing provides a new tool for differentiating active versus inactive microbial taxa throughout leaf litter decomposition. Prior research has demonstrated this technique using 16S rRNA gene sequencing to differentiate active versus inactive bacterial and archeal taxa. Here we demonstrate, for the first time, that qSIP combined with sequencing the internal transcribed spacer region (ITS) of rRNA genes can be used to identify fungal taxa that are actively growing on decomposing leaves. We applied this approach to a litter decomposition experiment in which cottonwood (Populus fremontii and P. angustifolia), ash (Fraxinus velutina ), and oak (Quercus gambelii) leaves were incubated in stream water for up to 24 days. Results show that the majority of fungal taxa found on leaf litter were not active. Analyzing the active taxa revealed significant differences in fungal community composition among leaf types and harvest dates. Additionally we compared bacterial and fungal responses across leaf types to characterize the relative activities of all members of the microbial assemblage during decomposition.

Michaela Hayer (Primary Presenter/Author), Northern Arizona University, michaela.hayer@nau.edu;


Rebecca Fritz (Co-Presenter/Co-Author), Northern Arizona University, rjf227@nau.edu;


Bruce Hungate (Co-Presenter/Co-Author), Northern Arizona University, bruce.hungate@nau.edu;


Benjamin Koch (Co-Presenter/Co-Author), Northern Arizona University, ben.koch@nau.edu;


Egbert Schwartz (Co-Presenter/Co-Author), Northern Arizona University, egbert.schwartz@nau.edu;


Jane Marks (Co-Presenter/Co-Author), Northern Arizona University, jane.marks@nau.edu;


Presentation:
This presentation has not yet been uploaded.

5/21/2018  |   14:30 - 14:45   |  330 A

THE MOSQUITO TREE HOLE ECOSYSTEM AS A HYPOXIC REDUCING ENVIRONMENT: IMPLICATIONS FOR VECTOR CONTROL Mosquitoes are important to human health because of their role as biological vectors for many serious pathogens and parasites causing infection and disease. The Yellow Fever Mosquito, Aedes aegypti, and the Asian Tiger Mosquito, Aedes albopictus, are vectors for the viral diseases Dengue fever, chikungunya, and zika, and utilize containers for larval habitat, including water-filled tree holes. Research on the ecosystem function of these habitats is crucial to understanding population dynamics and adult mosquito production of these and other Aedes species. The tree hole ecosystem is heterotrophic, with trophic processes dependent upon microbially-mediated decomposition of organic detritus and inputs of inorganic nutrients from stemflow water. For growth in this ecosystem, mosquito larvae consume microorganisms. We monitored natural tree holes over a mosquito growth season and showed that the tree hole ecosystem is a stably reducing environment where oxidation reduction potential varies and is associated with electron acceptor input during disturbance events and seasonal changes. We therefore challenge the assumption that tree hole production is nutrient-limited; instead, it is a nutrient-rich environment but hypoxic and with a deficit of electron acceptors to further microbial respirations and decomposition.

Kazem Kashefi (Co-Presenter/Co-Author), Michigan State University, kashefi@msu.edu;


Edward Walker (Co-Presenter/Co-Author), Michigan State University, walker@msu.edu;


Jennifer Kirk (Primary Presenter/Author), Michigan State University, kirkjen1@msu.edu;


Presentation:
This presentation has not yet been uploaded.

5/21/2018  |   14:45 - 15:00   |  330 A

ASSESSING BIOGEOGRAPHIC GAPS IN BACTERIAL DIVERSITY KNOWLEDGE: A GLOBAL REVIEW OF LOTIC HABITATS Freshwaters account for 0.01% of Earth’s water, 0.8% of surface area, yet supports ~10% of all known species making them disproportionately biodiverse compared to marine and terrestrial habitats. Molecular techniques have only recently been implemented to describe microbial diversity, thus we hypothesize that geographic coverage of microbial diversity knowledge is incomplete. We conducted a literature review to assess the global distribution of lotic habitats in which microbial community diversity has been sampled using modern molecular techniques. We identified 317 studies published from 1998 to 2017 that used metagenomes, next-generation sequencing, community fingerprinting, and cloning to characterize microbial diversity in lotic habitats. Most studies took place in temperate regions of North America (37% of studies), Europe (27%), and Asia (25%), while comparatively few were from tropical regions of South America (4%) and Africa (2%). This geographic bias toward temperate regions mirrors that of macro-organisms, and is likely a consequence of concentration of research institutions and their resources in the developed world. Our review illustrates how the future accumulation of tropical sampling is essential to accurately estimate global microbial diversity and understand its variation with respect to climate and land-use change.

Allison Veach (Primary Presenter/Author), Oak Ridge National Laboratory, veacham@ornl.gov;


Matthew Troia (Co-Presenter/Co-Author), University of Tennessee, mtroia@utk.edu;


Melissa Cregger (Co-Presenter/Co-Author), Oak Ridge National Laboratory, creggerma@ornl.gov;


Presentation:
This presentation has not yet been uploaded.

5/21/2018  |   15:00 - 15:15   |  330 A

POTENTIAL SYMBIOTIC NITROGEN PROVISIONING BY FRESHWATER INSECT GUT MICROBES THROUGH NITRATE REDUCTION. Freshwater insects (FWIs) face comparable nitrogen (N) limitations as their terrestrial equivalents (Elsner et al. 200). However, compared to terrestrial insects, little is known about the role of gut-associated microbiota in alleviating N limitation in FWIs. This is despite the existence of functional feeding group-specific gut microbial assemblages in FWIs (Pechal & Benbow, 2016, Ayayee at al., 2017 in review). Microbial nitrate reduction processes represent possible pathways for symbiotic N provisioning in FWIs. These processes can convert nitrate to nitrous oxide and nitrogen (incomplete denitrification)(Stief et al., 2009) or ammonium (NH4) (assimilatory and dissimilatory nitrate reduction, ANRA and DNRA, respectively). We present herein, the incorporation of 15N into the biomass of FWIs following incubation in filtered stream water or artificial stream water supplemented with labeled potassium nitrate (K15NO3). Uptake is in the form of 15NH4, mediated via the glutamine synthetase (GS)-glutamine:2-oxoglutarate amidotransferase (GOGAT) enzyme complex. Results highlight novel microbial nitrogen provisioning in freshwater insects. Stable isotope and gene expression data from additional studies using only nymphs of the Brown Drake mayfly (Ephemera Simulans), together with inhibitors of both ANRA and DNRA and ammonium assimilation, are pending.

Paul Ayayee (Primary Presenter/Author), University of Nebraska at Omaha, payayee@unomaha.edu;


Sohini Bhattacharyya (Co-Presenter/Co-Author), Kent State University, sbhatta6@kent.edu;


Laura Leff (Co-Presenter/Co-Author), Kent State University, lleff@kent.edu;


Presentation:
This presentation has not yet been uploaded.

5/21/2018  |   15:15 - 15:30   |  330 A

EARLY INSIGHTS INTO THE NEON PROJECT FOR LONG-TERM STUDIES OF AQUATIC MICROBIAL ECOLOGY The dynamic nature of freshwater ecosystems poses challenges to understanding and predicting how long-term changes will affect water quality, biodiversity and ecosystem function. While tools are available for characterizing microbial assemblages and their functions, the underlying factors controlling microbial processes and their responses to climate and land use changes are not well understood. The National Ecological Observatory Network (NEON) microbial sampling program utilizes a suite of microbial measurements in benthic and planktonic habitats in order to characterize microbial diversity and abundances. NEON employs an integrated sample design to produce spatially and temporally coordinated physical, chemical, and biological measurements across the Network, which consists of 34 sites across the U.S. Standardized sampling and analysis methods are carried out, and quality-controlled data are provided freely to the public. Currently available datasets from a subset of aquatic sites show seasonal trends in microbial planktonic abundances, and clear differences in physical and biological properties were observed between lakes, large rivers and streams. The availability of additional data products and specimens will also be discussed. These resources will enable new opportunities for research into large-scale, long-term impacts of environmental changes on aquatic ecosystems.

Stephanie Parker (Co-Presenter/Co-Author), Battelle, National Ecological Observatory Network (NEON), sparker@battelleecology.org;
NEON Aquatic Ecologist and Research Scientist

Lee Stanish (Primary Presenter/Author), National Ecological Observatory Network, lstanish@battelleecology.org;


Presentation:
This presentation has not yet been uploaded.