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Full-Text Articles in Life Sciences

Available Nitrogen And Denitrification In Soil Altered By Ground Cover And Nutrient Source In An Organic Apple Orchard, Jade Nicole Ford Dec 2015

Available Nitrogen And Denitrification In Soil Altered By Ground Cover And Nutrient Source In An Organic Apple Orchard, Jade Nicole Ford

Graduate Theses and Dissertations

A shift in public demand towards more organic and locally produced fruit and vegetables has been occurring across the United States in recent years. A common practice in organic fruit production is the application of organic ground covers to supply nutrients while enhancing other soil properties. A need for research exists in the southern region of the U.S. examining the effects of regionally applicable ground cover and nutrient management on nitrogen availability and the microbial community to provide information to organic farmers in the region. Two studies were conducted to determine how 12 treatment combinations of four ground covers (compost, …


Intrinsic Challenges In Ancient Microbiome Reconstruction Using 16s Rrna Gene Amplification, Kirsten Ziesemer, Allison Mann, Krithivasan Sankaranarayanan, Hannes Schroeder, Andrew T. Ozga, Bernd W. Brandt, Egija Zaura, Andrea Waters-Rist, Menno Hoogland, Domingo C. Salazar-Garcia, Mark Aldenderfer, Camilla Speller, Jessica Hendy, Darlene A. Weston, Sandy J. Macdonald, Gavin H. Thomas, Matthew J. Collins, Cecil M. Lewis Jr., Corinne Hofman, Christina Warinner Nov 2015

Intrinsic Challenges In Ancient Microbiome Reconstruction Using 16s Rrna Gene Amplification, Kirsten Ziesemer, Allison Mann, Krithivasan Sankaranarayanan, Hannes Schroeder, Andrew T. Ozga, Bernd W. Brandt, Egija Zaura, Andrea Waters-Rist, Menno Hoogland, Domingo C. Salazar-Garcia, Mark Aldenderfer, Camilla Speller, Jessica Hendy, Darlene A. Weston, Sandy J. Macdonald, Gavin H. Thomas, Matthew J. Collins, Cecil M. Lewis Jr., Corinne Hofman, Christina Warinner

Biology Faculty Articles

To date, characterization of ancient oral (dental calculus) and gut (coprolite) microbiota has been primarily accomplished through a metataxonomic approach involving targeted amplification of one or more variable regions in the 16S rRNA gene. Specifically, the V3 region (E. coli341–534) of this gene has been suggested as an excellent candidate for ancient DNA amplification and microbial community reconstruction. However, in practice this metataxonomic approach often produces highly skewed taxonomic frequency data. In this study, we use non-targeted (shotgun metagenomics) sequencing methods to better understand skewed microbial profiles observed in four ancient dental calculus specimens previously analyzed by amplicon …


The Functional And Distributional Ecology Of Mycetozoans Under Changing Edaphic And Climatic Dynamics, Geoffrey Lloyd Zahn Jul 2015

The Functional And Distributional Ecology Of Mycetozoans Under Changing Edaphic And Climatic Dynamics, Geoffrey Lloyd Zahn

Graduate Theses and Dissertations

Investigations into the distribution and ecosystem functions of fruiting amoebae revealed that local-scale environmental conditions can largely explain broad biogeographical patterns in species assemblage, the way in which amoeboid predators shape bacterial communities and how this top-down influence may affect global biogeochemical processes in a changing climate. The distribution and assemblage of protosteloid amoebae on the islands of New Zealand and Hawaii did not yield any expected patterns of island biogeography, and conformed to other global regions studied. The strongest predictor of species richness in a given region was sampling effort and these species do not appear to have any …


The Shellfish Corner -- Vibrios And Shellfish, Michael Rice May 2015

The Shellfish Corner -- Vibrios And Shellfish, Michael Rice

Michael A Rice

Pathogenic Vibrios are becoming an increasing problem for shellfish producers in North America and elsewhere. This paper reviews current research into the pathogenic nature of Vibrios and provides some practical advice for avoiding the propagation of Vibrios on shellfish farms nd in wild harvest molluscan shellfish.


Tree Islands Of Fertility Structure Bacterial Community Assembly And Functional Genes Contributing To Ecosystem Processes, Tayte Paul Campbell May 2015

Tree Islands Of Fertility Structure Bacterial Community Assembly And Functional Genes Contributing To Ecosystem Processes, Tayte Paul Campbell

Theses and Dissertations

In arid and semi-arid ecosystems, dominant tree species create dramatic mosaics of plant islands of fertility and relatively barren plant interspaces that exert immense pressure on ecosystem processes and offers an ideal opportunity to explore the impact of bacterial communities. We evaluated potential links between soil respiration and N mineralization, and community co-occurrence networks and predicted gene function across three tree island microsites (i.e., beneath tree canopies, at the canopy edge, and in interspaces) in a replicated field experiment in thirty-eight woodlands sites in the Great Basin Desert in UT, USA. Additionally, we potentially intensified the effects of tree islands …


Two Decades Of Warming Increases Diversity Of A Potentially Lignolytic Bacterial Community, Grace Pold, Jerry M. Melillo, Kristen Deangelis Jan 2015

Two Decades Of Warming Increases Diversity Of A Potentially Lignolytic Bacterial Community, Grace Pold, Jerry M. Melillo, Kristen Deangelis

Microbiology Department Faculty Publication Series

As Earth's climate warms, the massive stores of carbon found in soil are predicted to become depleted, and leave behind a smaller carbon pool that is less accessible to microbes. At a long-term forest soil-warming experiment in central Massachusetts, soil respiration and bacterial diversity have increased, while fungal biomass and microbially-accessible soil carbon have decreased. Here, we evaluate how warming has affected the microbial community's capability to degrade chemically-complex soil carbon using lignin-amended BioSep beads. We profiled the bacterial and fungal communities using PCR-based methods and completed extracellular enzyme assays as a proxy for potential community function. We found that …


Long-Term Forest Soil Warming Alters Microbial Communities In Temperate Forest Soils, Kristen Deangelis, Grace Pold, Begüm D. Topçuoğlu, Linda T.A. Van Diepen, Rebecca M. Varney, Jeffrey L. Blanchard, Jerry Melillo, Serita D. Frey Jan 2015

Long-Term Forest Soil Warming Alters Microbial Communities In Temperate Forest Soils, Kristen Deangelis, Grace Pold, Begüm D. Topçuoğlu, Linda T.A. Van Diepen, Rebecca M. Varney, Jeffrey L. Blanchard, Jerry Melillo, Serita D. Frey

Microbiology Department Faculty Publication Series

Soil microbes are major drivers of soil carbon cycling, yet we lack an understanding of how climate warming will affect microbial communities. Three ongoing field studies at the Harvard Forest Long-term Ecological Research (LTER) site (Petersham, MA) have warmed soils 5°C above ambient temperatures for 5, 8, and 20 years. We used this chronosequence to test the hypothesis that soil microbial communities have changed in response to chronic warming. Bacterial community composition was studied using Illumina sequencing of the 16S ribosomal RNA gene, and bacterial and fungal abundance were assessed using quantitative PCR. Only the 20-year warmed site exhibited significant …


Soil Bacterial Structure And Function Associated With The Invasive Grass Microsteguim Vimineum And Two Native Grasses, Jennifer Kay Bell Jan 2015

Soil Bacterial Structure And Function Associated With The Invasive Grass Microsteguim Vimineum And Two Native Grasses, Jennifer Kay Bell

Electronic Theses and Dissertations

Soil microorganisms play vital roles in biogeochemical cycles and are necessary for maintaining soil health. An invasive plant that alters the structure and function of the soil microbial assemblage could gain an advantage over native plants, enhancing its ability to invade new habitats, alter ecosystem function, and hinder efforts to reestablish native populations. Assays of enzyme activity and next generation sequencing of bacterial 16S rRNA genes were used to assess the soil microbial function and community structure associated with the invasive grass, Microstegium vimineum and two co-occurring native grasses (Dichanthelium boscii and Chasmanthium laxum). Significantly lower enzyme activity was found …