Biogeochemical research priorities for sustainable biofuel and bioenergy feedstock production in the Americas.

Rapid expansion in biomass production for biofuels and bioenergy in the Americas is increasing demand on the ecosystem resources required to sustain soil and site productivity. We review the current state of knowledge and highlight gaps in research on biogeochemical processes and ecosystem sustainability related to biomass production. Biomass production systems incrementally remove greater quantities of organic matter, which in turn affects soil organic matter and associated carbon and nutrient storage (and hence long-term soil productivity) and off-site impacts. While these consequences have been extensively studied for some crops and sites, the ongoing and impending impacts of biomass removal require management strategies for ensuring that soil properties and functions are sustained for all combinations of crops, soils, sites, climates, and management systems, and that impacts of biomass management (including off-site impacts) are environmentally acceptable. In a changing global environment, knowledge of cumulative impacts will also become increasingly important. Long-term experiments are essential for key crops, soils, and management systems because short-term results do not necessarily reflect long-term impacts, although improved modeling capability may help to predict these impacts. Identification and validation of soil sustainability indicators for both site prescriptions and spatial applications would better inform commercial and policy decisions. In an increasingly interrelated but constrained global context, researchers should engage across inter-disciplinary, inter-agency, and international lines to better ensure the long-term soil productivity across a range of scales, from site to landscape.Fil: Gollany, Hero T. USDA. Agricultural Research Service. Columbia Plateau Conservation Research Center; Estados UnidosFil: Titus, Brian D. Pacific Forestry Centre. Canadian Forest Service. Natural Resources Canada; CanadáFil: Scott, Andrew USDA Forest Service. Agricultural Research Center. Southern Research Station; Estados UnicosFil: Asbjornsen, Heidi. University of New Hampshire. Institute for Earth, Oceans and Space. Department of Natural Resources and the Environment and the Earth Systems Research Center; Estados UnidosFil: Resh, Sigrid C. Michigan Technological University. School of Forest Resources and Environmental Science; Estados UnidosFil: Chimner, Rodney Allen. Michigan Technological University. School of Forest Resources and Environmental Science; Estados UnidosFil: Kaczmarek, Donald J. Oregon Department of Forestry; Estados UnidosFil: Leite, Luiz F. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA); BrasilFil: Ferreira, Ana C. Climate Change Adaptation Consultant; BrasilFil: Rod, Kenton A. Washington State University. School of the Environment; Estados UnidosFil: Hilbert, Jorge Antonio. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Ingeniería Rural; ArgentinaFil: Galdos, Marcelo. Brazilian Center for Research in Energy and Materials (CNPEM). Brazilian Bioethanol Science and Technology Laboratory (CTBE); BrasilFil: Cisz, Michelle E. Michigan Technological University. School of Forest Resources and Environmental Science; Estados Unido

Acidosis Potentiates the Host Proinflammatory Interleukin-1β Response to Pseudomonas Aeruginosa Infection

Infection by Pseudomonas aeruginosa, and bacteria in general, frequently promotes acidification of the local microenvironment, and this is reinforced by pulmonary exertion and exacerbation. However, the consequence of an acidic environment on the host inflammatory response to P. aeruginosa infection is poorly understood. Here we report that the pivotal cellular and host proinflammatory interleukin-1β (IL-1β) response, which enables host clearance of the infection but can produce collateral inflammatory damage, is increased in response to P. aeruginosa infection within an acidic environment. Synergistic mechanisms that promote increased IL-1β release in response to P. aeruginosa infection in an acidic environment are increased pro-IL-1β induction and increased caspase-1 activity, the latter being dependent upon a functional type III secretion system of the bacteria and the NLRC4 inflammasome of the host. Using an in vivo peritonitis model, we have validated that the IL-1β inflammatory response is increased in mice in response to P. aeruginosa infection within an acidic microenvironment. These data reveal novel insights into the regulation and exacerbation of inflammatory responses to P. aeruginosa

Injection of Pseudomonas aeruginosa Exo Toxins into Host Cells Can Be Modulated by Host Factors at the Level of Translocon Assembly and/or Activity

Pseudomonas aeruginosa type III secretion apparatus exports and translocates four exotoxins into the cytoplasm of the host cell. The translocation requires two hydrophobic bacterial proteins, PopB and PopD, that are found associated with host cell membranes following infection. In this work we examined the influence of host cell elements on exotoxin translocation efficiency. We developed a quantitative flow cytometry based assay of translocation that used protein fusions between either ExoS or ExoY and the ß-lactamase reporter enzyme. In parallel, association of translocon proteins with host plasma membranes was evaluated by immunodetection of PopB/D following sucrose gradient fractionation of membranes. A pro-myelocytic cell line (HL-60) and a pro-monocytic cell line (U937) were found resistant to toxin injection even though PopB/D associated with host cell plasma membranes. Differentiation of these cells to either macrophage- or neutrophil-like cell lines resulted in injection-sensitive phenotype without significantly changing the level of membrane-inserted translocon proteins. As previous in vitro studies have indicated that the lysis of liposomes by PopB and PopD requires both cholesterol and phosphatidyl-serine, we first examined the role of cholesterol in translocation efficiency. Treatment of sensitive HL-60 cells with methyl-ß-cyclodextrine, a cholesterol-depleting agent, resulted in a diminished injection of ExoS-Bla. Moreover, the PopB translocator was found in the membrane fraction, obtained from sucrose-gradient purifications, containing the lipid-raft marker flotillin. Examination of components of signalling pathways influencing the toxin injection was further assayed through a pharmacological approach. A systematic detection of translocon proteins within host membranes showed that, in addition to membrane composition, some general signalling pathways involved in actin polymerization may be critical for the formation of a functional pore. In conclusion, we provide new insights in regulation of translocation process and suggest possible cross-talks between eukaryotic cell and the pathogen at the level of exotoxin translocation

Modified Needle-Tip PcrV Proteins Reveal Distinct Phenotypes Relevant to the Control of Type III Secretion and Intoxication by Pseudomonas aeruginosa

The type III secretion system (T3SS) is employed to deliver effector proteins to the cytosol of eukaryotic hosts by multiple species of Gram-negative bacteria, including Pseudomonas aeruginosa. Translocation of effectors is dependent on the proteins encoded by the pcrGVHpopBD operon. These proteins form a T3S translocator complex, composed of a needle-tip complex (PcrV), translocons (PopB and PopD), and chaperones (PcrG and PcrH). PcrV mediates the folding and insertion of PopB/PopD in host plasmic membranes, where assembled translocons form a translocation channel. Assembly of this complex and delivery of effectors through this machinery is tightly controlled by PcrV, yet the multifunctional aspects of this molecule have not been defined. In addition, PcrV is a protective antigen for P. aeruginosa infection as is the ortholog, LcrV, for Yersinia. We constructed PcrV derivatives containing in-frame linker insertions and site-specific mutations. The expression of these derivatives was regulated by a T3S-specific promoter in a pcrV-null mutant of PA103. Nine derivatives disrupted the regulation of effector secretion and constitutively released an effector protein into growth medium. Three of these regulatory mutants, in which the linker was inserted in the N-terminal globular domain, were competent for the translocation of a cytotoxin, ExoU, into eukaryotic host cells. We also isolated strains expressing a delayed-toxicity phenotype, which secrete translocators slowly despite the normal level of effector secretion. Most of the cytotoxic translocation-competent strains retained the protective epitope of PcrV derivatives, and Mab166 was able to protect erythrocytes during infection with these strains. The use of defined PcrV derivatives possessing distinct phenotypes may lead to a better understanding of the functional aspects of T3 needle-tip proteins and the development of therapeutic agents or vaccines targeting T3SS-mediated intoxication

Data and code from: Does the seagrass microbiome mediate risk of disease?

The data files are shared under a datasets will be shared under a Creative Commons Attribution NonCommercial 4.0 International license (CC BY-NC 4.0); the data will be openly available to share and adapt, but appropriate credit to the original data creators is required upon reuse, and the material may not be used for commercial purposes. The r code is being shared under a MIT License. Please see the header information in the .r file for more information.These files contain data and scripts supporting all results reported in Graham et al. paper, "Does the seagrass microbiome mediate risk of disease?". In Graham et al., we found: Microbial communities strongly influence the health and functions of their hosts and can be a first line of defense against infections. While research increasingly shows a role of the microbiome in terrestrial plant disease resistance, this has yet to be demonstrated with the diversity of pathogens infecting marine plants. Here, we test the hypothesis that the host-associated microbiome increases host resistance to seagrass wasting disease. We experimentally manipulated the eelgrass (Zostera marina) microbiome with antibiotics, mechanical removal by vortexing, and dilute bleach, then inoculated plants with Labyrinthula zosterae (Lz), the causative agent of seagrass wasting disease. Our experiments using different microbiome disruption methods consistently showed significantly higher disease severity in eelgrass with an unmanipulated microbiome. Indeed, our results did not support a protective role of the eelgrass microbiome against Lz. We paired these experiments with 16S rRNA gene sequencing of field-collected eelgrass to determine how microbial communities may change in different disease states. Microbial composition and richness between diseased and healthy (completely asymptomatic) tissue varied markedly in one of three sampling years, suggesting diseased eelgrass could have a degradation community under certain conditions. This work enhances our understanding of plant-microbe-pathogen interactions in a valuable marine foundation species.We thank Susan Lynch for providing CORALS program support for many of the authors. The following funds also supported this work: NSF award OCE-1829921 to CDH; the Andrew W. Mellon Student Research Grant, FHL Graduate Research Fellowship Endowment, Richard and Megumi Strathmann Fellowship to OJG; the UBC Four Year Doctoral Fellowship, UBC Zoology Graduate Fellowship, and funding from the Tula Foundation and the NSERC Canadian Healthy Oceans Network and its Partners: Department of Fisheries and Oceans Canada and INREST (representing the Port of Sept-Îles and City of Sept-Îles) to EMA, British Columbia graduate fellowship and UBC Ocean Leaders Fellowship to SS and NSERC Discovery Grant and Tula Foundation grants to LWP