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Microbial communities drive soil ecosystem function but are also susceptible to environmental disturbances. We investigated whether exposure to manure sourced from cattle either administered or not administered antibiotics affected microbially-mediated terrestrial ecosystem function. We quantified changes in microbial community composition, and terrestrial elemental cycling via a stable isotope pulse-chase. Exposure to manure from antibiotic-treated cattle caused: i) changes in microbial community structure; and ii) alterations in elemental cycling throughout the terrestrial system. This exposure caused changes in fungal:bacterial, as well as changes in bacterial community structure. Additionally, exposure to manure from cattle treated with pirlimycin resulted in an approximate two-fold increase in ecosystem respiration of recently fixed-carbon, and a greater proportion of recently-added nitrogen in plant and soil pools compared to the control manure. Manure from antibiotic-treated cattle therefore affects terrestrial ecosystem function via the soil microbiome, causing decreased ecosystem carbon use efficiency, and altered nitrogen cycling.

The American Chestnut (Castanea denata) was once the dominant hardwood species within the forests of the Appalachians and an important resource for people and wildlife. In the early 1900s, a fungal blight (Cryphonectria parasitica) was introduced from imported ‘Japanese Giant’ nursery trees that caused topkill of American chestnuts (Tallamy 2007). Trees infected with C. parasitica die back, then continually resprout from the roots. Since 1983, the American Chestnut Foundation has been conducting a backcross breeding program to produce hybrid trees resistant to the blight, and more recently, various research institutions have been working to develop transgenic varieties of American chestnut which express genes that may give the trees resistance to the blight. Additional pathogens, such as the fungus-like oomycete which causes root rot (Phytophthora cinnamomi), have furthered threatened C. dentata, and research of transgenic American chestnuts has included the identification of genes that may provide resistance to P. cinnamomi.

Despite a nationwide emphasis on improving soil health in the United States, current measurement protocols have little consistency. To survey assessment practices, we conducted a meta-analysis of cover crop (n = 86) and no-tillage (n = 106) studies and compiled reported indicators, cropping systems, and soil sampling protocols from each. We then analyzed which indicators significantly responded to cover crop usage after 1 yr and 2 to 3 yr. Our results showed that out of 42 indicators, only 8 were reported in >20% of studies. Thirteen indicators showed >10% relative response after 1 to 3 yr; the remainder lacked either sufficient observations or consistent results. Looking forward, we propose that emphasis should be placed on (i) pursuing dynamic indicators (e.g., aggregate stability), (ii) standardizing sampling protocols, and (iii) developing a common framework for information sharing. These efforts will generate new insight into soil health across systems, ultimately ensuring that soil health science is useful to producers and regulators. This work was supported by the US Department of Agriculture NRCS Conservation Innovation Grant #69-3A75-14-260. Funding was also provided by the Virginia Agricultural Experiment Station and the Hatch Program of the National Institute of Food and Agriculture, US Department of Agriculture (VA-160041). Funding was provided by the Virginia Tech Open Access Subvention Fund (VT OASF).

Humans may be exposed to microbial pathogens at recreational beaches via environmental sources such as water and sand. Although infectious disease risk from exposure to waterborne pathogens, and the fecal indicator bacteria (FIB) used to monitor water quality are active areas of research, sand is a relatively unexplored reservoir of pathogens and FIB. Sand and water at beaches experience continuous exchange of microorganisms, and these habitats provide unique advantages and challenges to pathogen introduction, growth, and persistence. Models of FIB and pathogen fate and transport in beach habitats can aid prediction of the risk of infectious disease from recreational water use, but filling knowledge gaps is necessary for accurate modeling. Climate change predictions estimate an increase in global temperatures of 2.5 – 10° F, sea level rise, and intensification of storms and precipitation in some regions. Other global change factors like population growth and urbanization may exacerbate predicted impacts. These changes can alter microbial population dynamics in beach habitats, and may consequently affect the assumptions and relationships used in numerical models. We discuss literature on microbial population and transport dynamics in sand/beach habitats, with an emphasis on how climate change and other anthropogenic influences (e.g., land use, urbanization) should be considered when using and developing models. N/A

Our vision is to create a program dedicated to accelerating innovation that improves the quality, efficiency, and resilience of human dominated landscapes, including our cities, farms, and industrial lands. Humans dramatically alter and manipulate the global landscape for food and fiber production, mineral extraction, urban development, waste disposal and many other purposes. Impacts to essential ecosystem functions and values range from local (e.g. mining and land development) to global (e.g. carbon emissions) with a clear need for development of appropriate management systems for their mitigation. By using a systems approach that interfaces environmental scientists and ecologists with relevant disciplines, this proposed signature area within Global Systems Science (GSS) will build upon existing group strengths in soil remediation, water quality, hydrology, urban soils, land reclamation, agroecosystem management, forest ecology, wetland restoration, soil-waste management and integrated modeling across multiple spatial and temporal scales to develop a more holistic approach to landscape management. We will also...

Microorganisms are absolutely critical to myriad aspects of the human existence. As a field of study, microbiology could and should serve a greater role on our campus, as it has key connections with many of the Destination and Strategic Growth Areas. We propose the development of a broad concept area in microbiology that will serve as a nexus, as it is applied to solve critical global challenges related to food, energy, water and health, by bridging across multiple disciplines at Virginia Tech (VT). There is increasing recognition of microbes as a driving force in natural and managed environments, biological processes, and ecological structure. Conversely, the importance of culture and individual behavior in affecting microbial communities has also become apparent....

The development of viable solutions to the global threat of antimicrobial resistance requires a transdisciplinary approach that simultaneously considers the clinical, biological, social, economic, and environmental drivers responsible for this emerging threat. The vision of the Antimicrobial Resistance Mitigation (ARM) group is to build upon and leverage the present strengths of Virginia Tech in ARM research and education using a multifaceted systems approach. Such a framework will empower our group to recognize the interconnectedness and interdependent nature of this threat and enable the delineation, development, and testing of resilient approaches for its mitigation. We seek to develop innovative and sustainable approaches that radically advance detection, characterization, and prevention of antimicrobial resistance emergence and dissemination in human-dominated and natural settings...

Water scarcity is mainly caused by overwhelming human consumption and contamination, from production of water-thirsty meats and vegetables, biofuel crop production, industrial uses, and rapid urbanization. The scale of water scarcity makes it an interconnected global issue and efforts to minimize the gap between water supply and demand are critical...

Plant establishment is a key component of land reclamation and restoration, but ultimately full recovery of other beneficial ecosystem services that were provided prior to disturbance is desired for successful restoration. Many of these ecosystem services, primarily related to nutrient cycling and other biogeochemical processes, are regulated by microorganisms. However, the factors that promote the return of beneficial soil microorganisms – and the ecological functions they perform – to restored ecosystems are not well understood. Our previous work in the Powell River Project has discovered that the type of vegetation used to reforest reclaimed mine soils may not only control the resulting plant community, but also the trajectory of the soil microbial community and the processes they mediate related to important ecosystem services. In this work, we experimentally tested the hypothesis that carbon substrate diversity, provided by plant root exudates, is an important mechanism in shaping soil microbial communities as ecosystems recover. In a controlled greenhouse experiment, we analyzed microbial community structure and diversity of dissolved organic carbon substrates in experimental PRP soil mesocosms planted with one of five plant diversity treatments: chicory, clover, foxtail, rye, or an even mix of all four. Results indicate that plant species has significant effects on soil dissolved organic carbon substrate quantity and quality, as well as soil microbial community structure, with clover and chicory resulting in the most distinct changes. In addition, among the non-leguminous plant species, patterns of carbon substrate and microbial diversity tracked each other, suggesting an important interaction between the two.

This file contains supplementary figures and tables for Wepking et al.