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Our study goal was to investigate the impact of biocides and nanoparticles (NPs) on the microbial diversity in a hydraulic fracturing impacted stream. Biocides and NPs are known for their antimicrobial properties and controlling microbial growth. Previous work has shown that biocides can alter the microbial community composition of stream water and may select for biocide-resistant bacteria. Additional studies have shown that nanoparticles can also alter microbial community composition. However, previous work has often focused on the response to a single compound. Here we provide a more thorough analysis of the microbial community response to three different biocides and three different nanoparticles. A microcosm-based study was undertaken that exposed stream microbial communities to either biocides or NPs. Our results showed a decrease in bacterial abundance with different types of nanoparticles, but an increase in microbial abundance in biocide-amended treatments. The microbial community composition (MCC) was distinct from the controls in all biocide and NP treatments, which resulted in differentially enriched taxa in the treatments compared to the controls. Our results indicate that NPs slightly altered the MCC compared to the biocide-treated microcosms. After 14 days, the MCC in the nanoparticle-treated conditions was similar to the MCC in the control. Conversely, the MCC in the biocide-treated microcosms was distinct from the controls at day 14 and distinct from all conditions at day 0. This finding may point to the use of NPs as an alternative to biocides in some settings.

Background Microbial electrolysis is a promising technology for converting aqueous wastes into hydrogen. However, substrate adaptability is an important feature, seldom documented in microbial electrolysis cells (MECs). In addition, the correlation between substrate composition and community structure has not been well established. This study used an MEC capable of producing over 10 L/L-day of hydrogen from a switchgrass-derived bio-oil aqueous phase and investigated four additional substrates, tested in sequence on a mature biofilm. The additional substrates included a red oak-derived bio-oil aqueous phase, a corn stover fermentation product, a mixture of phenol and acetate, and acetate alone. Results The MECs fed with the corn stover fermentation product resulted in the highest performance among the complex feedstocks, producing an average current density of 7.3 ± 0.51 A/m2, although the acetate fed MECs outperformed complex substrates, producing 12.3 ± 0.01 A/m2. 16S rRNA gene sequencing showed that community structure and community diversity were not predictive of performance, and replicate community structures diverged despite identical inoculum and enrichment procedure. The trends in each replicate, however, were indicative of the influence of the substrates. Geobacter was the most dominant genus across most of the samples tested, but its abundance did not correlate strongly to current density. High-performance liquid chromatography (HPLC) showed that acetic acid accumulated during open circuit conditions when MECs were fed with complex feedstocks and was quickly degraded once closed circuit conditions were applied. The largest net acetic acid removal rate occurred when MECs were fed with red oak bio-oil aqueous phase, consuming 2.93 ± 0.00 g/L-day. Principal component analysis found that MEC performance metrics such as current density, hydrogen productivity, and chemical oxygen demand removal were closely correlated. Net acetic acid removal was also found to correlate with performance. However, no bacterial genus appeared to correlated to these performance metrics strongly, and the analysis suggested that less than 70% of the variance was accounted for by the two components. Conclusions This study demonstrates the robustness of microbial communities to adapt to a range of feedstocks and conditions without relying on specific species, delivering high hydrogen productivities despite differences in community structure. The results indicate that functional adaptation may play a larger role in performance than community composition. Further investigation of the roles each microbe plays in these communities will help MECs to become integral in the 21st-century bioeconomy to produce zero-emission fuels.

Microorganisms play vital roles in Earth's biogeochemical cycles. Identifying disturbances in microbial communities due to anthropogenic contamination can provide insights into the health of ecosystems. Picher, Oklahoma, was the site of large-scale mining operations for Pb, Zn, and other heavy metals until the mid-1950s, operating within the Tri-State Mining District (TSMD) of Missouri, Kansas and Oklahoma. Although mining ceased decades ago, high concentrations of heavy metals (>1000 ppm) remain in area soil and water systems. Previously, we mapped metal concentrations on samples collected from mine tailings in Picher and along cardinal-direction transects within an 8.05-km radius of the town. To elucidate changes in microbial community structure due to regional metal contamination, 16S rRNA gene sequences and qPCR calculations of total Bacteria and Archaea were analyzed against these metal concentrations. Bacteria were negatively and significantly correlated with Pb, Cd, Zn, and Mg; however, Archaea was only significantly and positively correlated with pH. Illumina sequencing of 16S rRNA genes showed significant differences in microbial communities of chat and west transect samples. Comparison of soil chemistry with community structure indicated that Al, Pb, Cd, and Zn significantly impacted community composition and distribution of individual OTUs. Mapping the distribution of heavy-metal contamination and microbial communities in these soils represents the first step in understanding effects of long-term, heavy-metal contamination at a basic trophic level.

Shale gas production is a water and energy-intensive process that has expanded rapidly in the United States in recent years. This study compared the life cycle water consumption and greenhouse gas emissions from hydraulic fracturing in the Barnett region of Texas, located in one of the most drought prone regions of the United States. Four wastewater treatment scenarios were compared for produced water management in the Barnett region. For each scenario, the cradle-to-gate life cycle global warming potential and water scarcity footprint was estimated per mega joule of gas produced. The results show a trade-off between water and carbon impacts, because energy is required for treatment of water. A reduction of 49 percent in total water consumed or a 28 percent reduction in the water scarcity footprint in the shale gas production process can be achieved at a cost of a 38 percent increase in global warming potential, if the wastewater management shifted from business as usual to complete desalination and reuse of produced water. The results are discussed in the context of wastewater management options available in Texas.

Horizontal drilling and hydraulic fracturing extraction procedures have become increasingly present in Pennsylvania where the Marcellus Shale play is largely located. The potential for long-term environmental impacts to nearby headwater stream ecosystems and aquatic bacterial assemblages is still incompletely understood. Here, we perform high-throughput sequencing of the 16 S rRNA gene to characterize the bacterial community structure of water, sediment, and other environmental samples (n = 189) from 31 headwater stream sites exhibiting different histories of fracking activity in northwestern Pennsylvania over five years (2012–2016). Stream pH was identified as a main driver of bacterial changes within the streams and fracking activity acted as an environmental selector for certain members at lower taxonomic levels within stream sediment. Methanotrophic and methanogenic bacteria (i.e. Methylocystaceae, Beijerinckiaceae, and Methanobacterium) were significantly enriched in sites exhibiting Marcellus shale activity (MSA+) compared to MSA− streams. This study highlighted potential sentinel taxa associated with nascent Marcellus shale activity and some of these taxa remained as stable biomarkers across this five-year study. Identifying the presence and functionality of specific microbial consortia within fracking-impacted streams will provide a clearer understanding of the natural microbial community’s response to fracking and inform in situ remediation strategies.

The environmental impacts of hydraulic fracturing, particularly those of surface spills in aquatic ecosystems, are not fully understood. The goals of this study were to (1) understand the effect of previous exposure to hydraulic fracturing fluids on aquatic microbial community structure and (2) examine the impacts exposure has on biodegradation potential of the biocide glutaraldehyde. Microcosms were constructed from hydraulic fracturing-impacted and nonhydraulic fracturing-impacted streamwater within the Marcellus shale region in Pennsylvania. Microcosms were amended with glutaraldehyde and incubated aerobically for 56 days. Microbial community adaptation to glutaraldehyde was monitored using 16S rRNA gene amplicon sequencing and quantification by qPCR. Abiotic and biotic glutaraldehyde degradation was measured using ultra-performance liquid chromatography--high resolution mass spectrometry and total organic carbon. It was found that nonhydraulic fracturing-impacted microcosms biodegraded glutaraldehyde faster than the hydraulic fracturing-impacted microcosms, showing a decrease in degradation potential after exposure to hydraulic fracturing activity. Hydraulic fracturing-impacted microcosms showed higher richness after glutaraldehyde exposure compared to unimpacted streams, indicating an increased tolerance to glutaraldehyde in hydraulic fracturing impacted streams. Beta diversity and differential abundance analysis of sequence count data showed different bacterial enrichment for hydraulic fracturing-impacted and nonhydraulic fracturing-impacted microcosms after glutaraldehyde addition. These findings demonstrated a lasting effect on microbial community structure and glutaraldehyde degradation potential in streams impacted by hydraulic fracturing operations.

© 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology. Leveraging nature's biocomplexity for solving human problems requires better understanding of the syntrophic relationships in engineered microbiomes developed in bioreactor systems. Understanding the interactions between microbial players within the community will be key to enhancing conversion and production rates from biomass streams. Here we investigate a bioelectrochemical system employing an enriched microbial consortium for conversion of a switchgrass-derived bio-oil aqueous phase (BOAP) into hydrogen via microbial electrolysis (MEC). MECs offer the potential to produce hydrogen in an integrated fashion in biorefinery platforms and as a means of energy storage through decentralized production to supply hydrogen to fuelling stations, as the world strives to move towards cleaner fuels and electricity-mediated transportation. A unique approach combining differential substrate and redox conditions revealed efficient but rate-limiting fermentation of the compounds within BOAP by the anode microbial community through a division of labour strategy combined with multiple levels of syntrophy. Despite the fermentation limitation, the adapted abilities of the microbial community resulted in a high hydrogen productivity of 9.35 L per L-day. Using pure acetic acid as the substrate instead of the biomass-derived stream resulted in a three-fold improvement in productivity. This high rate of exoelectrogenesis signifies the potential commercial feasibility of MEC technology for integration in biorefineries.

The nitrogen cycle in the marine environment is strongly affected by ammonia-oxidizing Thaumarchaeota. In some marine settings, Thaumarchaeotes can comprise a large percentage of the prokaryotic population. To better understand the biogeographic patterns of Thaumarchaeotes, we sought to investigate differences in their abundance and phylogenetic diversity between geographically distinct basins. Samples were collected from four marine basins (The Caspian Sea, the Great Australian Bight, and the Central and Eastern Mediterranean). The concentration of bacterial and archaeal 16S rRNA genes and archaeal amoA genes were assessed using qPCR. Minimum entropy decomposition was used to elucidate the fine-scale diversity of Thaumarchaeotes. We demonstrated that there were significant differences in the abundance and diversity of Thaumarchaeotes between these four basins. The diversity of Thaumarchaeotal oligotypes differed between basins with many oligotypes only present in one of the four basins, which suggests that their distribution showed biogeographic patterning. There were also significant differences in Thaumarchaeotal community structure between these basins. This would suggest that geographically distant, yet geochemically similar basins may house distinct Thaumarchaeaotal populations. These findings suggest that Thaumarchaeota are very diverse and that biogeography in part contributes in determining the diversity and distribution of Thaumarchaeotes., Archaea are dominant in the water column in most deep marine basins; however, geographically distant, yet geochemically similar basins may house distinct ammonium-oxidizing Thaumarchaeaotal populations.

Valley of death describes the metaphorical depths to which promising science and technology too often plunge, never to emerge and reach their full potential. Behavioral and institutional perspectives help in understanding the implications of choices that inadvertently lead into rather than over the valley of death. A workshop conducted among a diverse set of scientists, managers, and technology transfer staff at a U.S. national laboratory is a point of departure for discussing behavioral and institutional elements that promote or impede the pathway from research toward use, and for suggesting actionable measures that can facilitate the flow of information and products from research toward use. In the complex systems that comprise research institutions, where competing pressures can create barriers to information or technology transfer, one recommendation is to re-frame the process as a more active ushering toward use.

Factors that shape actual research practices – ‘social and institutional context' – typically are missing from considerations of synthetic biology R&D-related risk and containment. We argue that analyzing context is essential in identifying circumstances that create, amplify, or diminish risk, and in revealing new opportunities for avoiding or managing those risks.

[1] The Sierra Madre del Sur mountain range is an uplifted forearc associated with the subduction of the Cocos plate along the Acapulco trench beneath mainland southern Mexico. The shallow subduction angle, the truncation of geologic features along the modern Acapulco trench, and direct seismic and drill hole observations in the trench through deep sea drilling data suggest that subduction erosion is an important process during the evolution of this margin. Turbidites derived from the uplifted forearc are the predominant sedimentary input into this trench, while pelagic sediments are subordinate. Apatite (U-Th)/He ages were obtained on 23 samples from two transects across the Sierra Madre del Sur (Acapulco and Puerto Escondido) and reveal slow cooling during the Miocene. (U-Th)/He ages range between ∼25 and 8 Ma and correlate inversely with elevation. Long-term erosional exhumation rates inferred from these ages range from 0.11 to 0.33 km/m.y., with higher rates in the range core, and suggest that the Sierra Madre del Sur has been a slowly decaying mountain range, since at least the early Miocene. Apparent Miocene-Pliocene sedimentation (“preservation”) rates in the Acapulco trench derived from Deep Sea Drilling Project data are about an order of magnitude smaller than the Miocene forearc erosion rates estimated from (U-Th)/He ages, suggesting that the terrigenous input to the trench was almost entirely recycled via subduction erosion, at least during the Miocene. The Miocene subducted flux per unit length of the margin is about 30 km3/(km m.y.), or a subducted volume per unit time of 44 × 103 km3/m.y., when integrated over the length of the trench.

About 80% of the southern part of the North American Cordillera within the Republic of Mexico is made up of suspect terranes. These terranes are suspect because their paleogeographic setting with respect to cratonic North America at various times through much of Phanerozoic time is uncertain. Much of northeastern and southeastern Mexico is underlain by basement accreted during late Paleozoic time, an extension of the Appalachian–Ouachita orogeny. This orogen has been considerably modified by Jurassic strike-slip translations related to the opening of the Gulf of Mexico. Western and southwestern Mexico is largely made up of several distinct but coeval latest Jurassic to Late Cretaceous submarine magmatic arc terranes with unknown basement that appear to have accreted against the disrupted North American margin by early Tertiary time. Only northeastern Sonora and the State of Chihuahua appear to be floored by unmoved North American cratonic basement. The combined effect of Mesozoic accretions and translations essentially eliminates the overlap of South America upon Mexico that is drived from late Paleozoic – early Mesozoic reconstructions of the closed Atlantic Ocean. This new vision of accretionary and translational tectonics in Mexico has profound implications for the study of tectogenesis in the southern Cordillera as well as for the interpretation of Mexico's vast natural resources. Preliminary analysis indicates that Mexico's gold–silver and lead–zinc deposits are directly or indirectly related to the terrane distributions discussed.

Scholars studying the ethical, legal, and social issues (ELSI) associated with emerging technologies maintain the importance of considering these issues throughout the research and development cycle, even during the earliest stages of basic research. Embedding these considerations within the scientific process requires communication between ELSI scholars and the community of physical scientists who are conducting that basic research. We posit that this communication can be effective on a broad scale only if it links societal issues directly to characteristics of the emerging technology that are relevant to the physical and natural scientists involved in research and development. In this article, we examine nano-ELSI literature from 2003 to 2010 to discern the degree to which it makes these types of explicit connections. We find that, while the literature identifies a wide range of issues of societal concern, it generally does so in a non-specific manner. It neither links societal issues to particular forms or characteristics of widely divergent nanotechnologies nor to any of the many potential uses to which those nanotechnologies may be put. We believe that these kinds of specificity are essential to those engaged in nano-scale research. We also compare the literature-based findings to observations from interviews we conducted with nanoscientists and conclude that ELSI scholars should add technical- and application-related forms of specificity to their work and their writings to enhance effectiveness and impact in communicating with one important target audience—members of the nanoscale science community.