Confirmed plenary presenters are: 

 

Microbe managing by making drugs out of bugs

 

Emma Allen-Vercoe, Department of Molecular and Cellular Biology, University of Guelph, Canada

 

There is now abundant evidence that the microbial consortium associated with its host – its microbiome – is critically important to the health of the host.  In the gut microbiota, health is generally associated with high species diversity.  When this diversity is degraded, e.g. through the use of antibiotics or the consumption of a poor diet, damage to the microbial ecosystem in the form of loss of key species may occur.  In these cases, there exists an opportunity to mitigate the damage by introducing microbial communities therapeutically.  However, a major barrier to this approach is understanding how best to predict which microbial species should be used to rectify ecosystem damage.  One approach might be to introduce established probiotic species; however, the metabolic capacity of this relatively narrow group of organisms can be restrictive.  Another approach is to introduce an entire microbial ecosystem from healthy donor stool; however, there are inherent risks associated with ‘fecal microbial transplant’ (FMT) that are difficult to overcome.  A newer approach, representing a balance between therapies using probiotics and fecal transplants, is ‘microbial ecosystem therapeutics’.  In this approach, gut microbial species are isolated from a healthy donor, purified, fully-characterized and preserved, and then recombined to create a defined microbial ecosystem with beneficial properties.  This approach has the benefit of both increased metabolic function relative to traditional probiotics, as well as increased safety relative to FMT, since cultured isolates can be extremely well-defined using cutting-edge tools, and ecosystems can be reproduced highly effectively.   In this talk I will discuss the utility and the practical considerations of microbial ecosystem therapeutics, and the work that my lab has been doing to develop and study defined microbial ecosystems to answer fundamental questions of gut microbial ecology, as a foundation to producing microbial therapeutics for treatment of disease on a commercial scale.

 

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On the Origin of Species by Means of Symbiosis

 

Seth Bordenstein, Departments of Biological Sciences and Pathology, Microbiology, & Immunology, Vanderbilt University, USA

 

Unprecedented attention to the microbial world has significantly turned the fields of zoology and botany inward—toward a new awareness and understanding of the microbial associates within hosts. Growing research initiatives now conceptualize individual hosts as holobionts - the sum of a host and its associated microbial bionts that can vary in time, space and function. This talk will explore how the holobiont concept diversifies questions and experiments related to the origin of species. Specifically, how do closely related host species vary in their microbial communities? If different host species have distinguishable microbiomes, do they exhibit phylosymbiosis? What evolutionary forces (selection vs. neutrality) underpin phylosymbiosis? How consequential are microbial symbionts and communities to host reproductive isolation and speciation?  Overall, answers to these questions demonstrate that reproductive and gut microbiomes fundamentally impact host evolution, physiology, and fitness, even across wide-ranging timescales and diverse animal systems. A holistic appreciation of genetics and microbial symbiosis in speciation will throw brighter light on Darwin's mystery of mysteries.

 

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Communication from a distance

 

Paolina Garbeva, Netherlands Insitute of Ecology, The Netherlands

 

Communication, is not restricted to verbal language. Communication is very often chemical and relies on the production and perception of secondary metabolites. For example volatiles, they are important infochemicals known to play essential role in above ground inter-kingdom interactions. Research on the function of volatile organic compounds is focused primarily on the interactions between plants and insects. However, microorganisms can also emit a plethora of volatiles that play an important role in intra- and inter-kingdom interactions.

In my talk I will briefly summarize the current knowledge on the biological functions of microbial volatiles with the focus on belowground interactions. I will pinpointed microbial volatiles involved in microbe-microbe and plant-microbe interactions, and will highlight the ecological importance of microbial volatiles for plant health. I will also indicate challenges in studying belowground volatile-mediated interactions and opportunities for further studies and practical applications.

 

 

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Microbial-host codevelopment in cnidarian holobionts from jellyfish to corals.

 

Mónica Medina, Department of Biology, The Pennsylvania State University, USA

 

I will present examples from interactions between microbial species and cnidarian hosts during different life history stages. A broad range of bacterial taxa affect the rate at which cnidarian larvae settle on substrates and metamorphose into benthic polyps. At the same time, the establishment of photosymbiosis with dinoflagellates in the family Symbiodiniacea is critical in enabling some cnidarian hosts to complete their life cycles (jellyfish) and others (scleractinian corals) to build reefs that harbor the highest marine biodiversity on Earth. The study of cnidarian holobionts illustrate the critical role microbiomes play in both organismal and ecosystem function.

 

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Diversity, Stability, and Resilience in Mammalian Microbiomes

 

David Relman, Department of Medicine - Med/Infectious Diseases, Stanford, USA

 

All complex ecosystems, such as host-associated microbial ecosystems, are shaped by forces of selection and other ecological processes. They also display multiple, alternative stable states. Regime shifts, or transitions from one state to another, occur in response to disturbance or change in the environment. In humans, these environmental changes might include the effects of pregnancy, aging, loss of salivary flow, or of immunosuppressing drugs. Resilience refers to resistance to ecosystem state shift or to recovery of prior ecosystem services following disturbance. Given the known and suspected benefits that humans derive from their microbiota, the stability and resilience of this ecosystem are critical properties that deserve attention. We have undertaken longitudinal studies in human subjects, some of whom are monitored before and after a standardized pulse, or acute disturbance, with the goals of describing the temporal dynamics of the human microbiome, and identifying features that are associated with stability in the face of disturbance as well as recovery of a prior state. A predictive understanding of the microbiome and the mechanisms that underlie resilience will inform effective strategies for its manipulation, so as to maintain or restore health, and avoid or mitigate disease.

 

 

 

Hormones and the Holobiont:   Origins and some implications of hologenome theory

 

Richard A. Jefferson, Queensland University of Technology, Brisbane, Australia

 

Multicellularity requires coordination of spatially distal cells and temporally diverse actions.  In vertebrates, much of this is mediated by hormones, frequently steroids, most of which are excreted through apocrine, exocrine and endocrine secretions as inactive conjugates of glucuronic acid or sulfate.   Myriad, diverse microbiota populate the epithelia and through cleavage by diverse glucuronidases (GUS) and arylsulfatases (ARS), release the active form of the hormone which can then be resorbed or presented with altered kinetics, bioactivity and concentrations to diverse sites of action.   The microbial populations thus modulate hormone action.

 

From 1980-1990, we developed and distributed GUS from E. coli as a reporter gene for plant, fungal and animal transgenesis and for microbial ecology studies.    In our efforts to improve its efficacy, we explored glucuronide operon function in enteric microbes, and sought natural GUS variants in populations of soil, water, epithelial or fecal microbes that might have improved properties.  We made field trips to Africa to isolate fecal and environmental microbes that were unlikely to be present due to human action and contamination.   In parallel we revisited neglected literature on the function of the enzymes in vertebrate biology.   In combination with stunning advances in microbial discovery and identification (e.g. David Ward’s & Steve Giovannoni’s discoveries of the ubiquity of uncultured microbes), and some neglected industrial R&D we were led to a major rethink on much of our framework around biology and evolution, science and society. This led to articulation of the hologenome theory of evolution at Cold Spring Harbor in 1994 and the extended proposal that hormone activity in metazoa and metaphyta was modulated by the dynamic population structures of associated microbes.  The pleiotropic and powerful effect that hormone modulation could have to reorient and impact virtually all fitness-related traits, and indeed all reproductive activity of plants and animals, stimulated new insights into living systems.   In this presentation I’ll review the coincidences and congruences that led to the theory and some of the possible implications for science and society, in the form of some conjectures.

 

Did the advent of agriculture and the concomitant rise in sedentary and concentrated populations cause massive inbreeding depression of the microbiome and become the origin of disease - plant, animal and human - as dysbiosis?    Is the germ theory of disease opportunistically right but structurally wrong?     Did commensalism and community tactility/touching - the hallmarks of social behavior - cause harmonization and reinforce convergent microbial populations and thus congruent hormone action and hence behavior?    Has all of evolutionary thought been compromised by scale bias?    Is it reasonable that the logic of evolution is embedded in macro-organisms (e.g. anything we can see) rather than the vast majority of all living systems that we can’t?  Is the holobiont - in the case of all systems that have experienced the post agricultural microbial collapse -  really a merobiont, with at best metastable populations that do not reflect an empirical steady state?   Is Darwin’s natural selection an ‘edge-case’ in evolution, working well at medium physical and temporal scales, but not truly reflecting the primacy of information-state persistence that could describe microbial life?   Could the hologenome theory and the microbiome provide the missing mechanism to the late 19th century’s other great evolutionist - now largely forgotten - Pyotr Kropotkin, who proposed ‘Mutual Aid: a factor in evolution” in 1902?   Could the real driver of evolution not be replication and reproduction, but persistence and pooing?  Can the role of macro-apobionts be largely as dynamic scaffolds to recruit, select,nurture, amplify and disseminate microbial populations?