Altered Antibiotic Tolerance in Anaerobic Digesters Acclimated to Triclosan Or Triclocarban

Bench-scale anaerobic digesters were amended to elevated steady-state concentrations of triclosan (850 mg/kg) and triclocarban (150 mg/kg) using a synthetic feed. After more than 9 solids retention time (SRT) values of acclimatization, biomass from each digester (and a control digester that received no antimicrobials) was used to assess the toxicity of three antibiotics. Methane production rate was measured as a surrogate for activity in microcosms that received doses of antibiotics ranging from no-antibiotic to inhibitory concentrations. Biomass amended with triclocarban was more sensitive to tetracycline compared to the control indicating synergistic inhibitory effects between this antibiotic and triclocarban. In contrast, biomass amended with triclosan was able to tolerate statistically higher levels of ciprofloxacin indicating that triclosan can induce functional resistance to ciprofloxacin in an anaerobic digester community

Learning the Lessons of Openness

The Open Educational Resources (OER) movement has built up a record of experience and achievements since it was formed 10 years ago as an identifiable approach to sharing online learning materials. In its initial phase, much activity was driven by ideals and interest in finding new ways to release content, with less direct research and reflection on the process. It is now important to consider the impact of OER and the types of evidence that are being generated across initiatives, organisations and individuals. Drawing on the work of OLnet (http://olnet.org) in bringing people together through fellowships, research projects and supporting collective intelligence about OER, we discuss the key challenges facing the OER movement. We go on to consider these challenges in the context of another project, Bridge to Success (http://b2s.aacc.edu), identifying the services which can support open education in the future

Recovery of Agricultural Nutrients from Biorefineries

This review lays the foundation for why nutrient recovery must be a key consideration in design and operation of biorefineries and comprehensively reviews technologies that can be used to recover an array of nitrogen, phosphorus, and/or potassium-rich products of relevance to agricultural applications. Recovery of these products using combinations of physical, chemical, and biological operations will promote sustainability at biorefineries by converting low-value biomass (particularly waste material) into a portfolio of higher-value products. These products can include a natural partnering of traditional biorefinery outputs such as biofuels and chemicals together with nutrient-rich fertilizers. Nutrient recovery not only adds an additional marketable biorefinery product, but also avoids the negative consequences of eutrophication, and helps to close anthropogenic nutrient cycles, thereby providing an alternative to current unsustainable approaches to fertilizer production, which are energy-intensive and reliant on nonrenewable natural resource extraction

Elements of Clausal Embedding

This thesis asks: what is the division of labour between the syntax and the semantics? The empirical focus is on the phenomenon of clausal embedding, whereby the grammar provides the resources to embed a clause within another clause, and the semantics provides the resources to represent an individual’s mental representations. The primary goal is to argue that that-clauses denote predicates of contentful entities – abstract objects, such as propositions, facts, and rumours. The major theoretical claim is that that-clauses function quite generally as modifiers in the compositional semantics, both when they compose with nominals and verbs. In order to cash this idea out, a strictly neo-Davidsonian approach to the syntax-semantics interface is outlined. In the syntax, arguments are severed from the verb; rather, they are incorporated as specifiers of functional heads. This is paralleled by a neo-Davidsonian semantics, where verbs denote predicates of eventualities, and thematic arguments are incorporated via metalanguage functions. Consequently all verbs, including attitude verbs, are argued to simply denote predicates of eventualities. Embedded clauses compose with attitude verbs as intersective modifiers – they specify the content of the verb’s eventuality argument

Generalised Crossover

Crossover (CO) is a constraint on anaphoric dependencies, according to which, quantifier scope can feed pronominal anaphora unless the anaphoric expression precedes the quantifier. We demonstrate that effects reminiscent of CO arise with presupposition as well, and propose to generalise CO as follows: Projective content (quantifier scope, presupposition projection, etc.) feeds semantic dependencies (pronominal anaphora, presupposition satisfaction), unless the semantically dependent expression precedes the trigger of the projective content. We call this generalisation, Generalised Crossover (GCO). Although we cannot offer a full explanation for GCO in this paper, we will discuss its implications for recent theories of CO

Triclocarban Influences Antibiotic Resistance and Alters Anaerobic Digester Microbial Community Structure

Triclocarban (TCC) is one of the most abundant organic micropollutants detected in biosolids. Lab-scale anaerobic digesters were amended with TCC at concentrations ranging from the background concentration of seed biosolids (30 mg/kg) to toxic concentrations of 850 mg/kg to determine the effect on methane production, relative abundance of antibiotic resistance genes, and microbial community structure. Additionally, the TCC addition rate was varied to determine the impacts of acclimation time. At environmentally relevant TCC concentrations (max detect = 440 mg/kg), digesters maintained function. Digesters receiving 450 mg/kg of TCC maintained function under gradual TCC addition, but volatile fatty acid concentrations increased, pH decreased, and methane production ceased when immediately fed this concentration. The concentrations of the mexB gene (encoding for a multidrug efflux pump) were higher with all concentrations of TCC compared to a control, but higher TCC concentrations did not correlate with increased mexB abundance. The relative abundance of the gene tet(L) was greater in the digesters that no longer produced methane, and no effect on the relative abundance of the class 1 integron integrase encoding gene (intI1) was observed. Illumina sequencing revealed substantial community shifts in digesters that functionally failed from increased levels of TCC. More subtle, yet significant, community shifts were observed in digesters amended with TCC levels that did not inhibit function. This research demonstrates that TCC can select for a multidrug resistance encoding gene in mixed community anaerobic environments, and this selection occurs at concentrations (30 mg/kg) that can be found in full-scale anaerobic digesters (U.S. median concentration = 22 mg/kg, mean = 39 mg/kg)

Chronic Exposure to Triclosan Sustains Microbial Community Shifts and Alters Antibiotic Resistance Gene Levels in Anaerobic Digesters

Triclosan, an antimicrobial chemical found in consumer personal care products, has been shown to stimulate antibiotic resistance in pathogenic bacteria. Although many studies focus on antibiotic resistance pertinent to medical scenarios, resistance developed in natural and engineered environments is less studied and has become an emerging concern for human health. In this study, the impacts of chronic triclosan (TCS) exposure on antibiotic resistance genes (ARGs) and microbial community structure were assessed in lab-scale anaerobic digesters. TCS concentrations from below detection to 2500 mg kg−1 dry solids were amended into anaerobic digesters over 110 days and acclimated for \u3e3 solid retention time values. Four steady state TCS concentrations were chosen (30–2500 mg kg−1). Relative abundance of mexB, a gene coding for a component of a multidrug efflux pump, was significantly higher in all TCS-amended digesters (30 mg kg−1 or higher) relative to the control. TCS selected for bacteria carrying tet(L) and against those carrying erm(F) at concentrations which inhibited digester function; the pH decrease associated with digester failure was suspected to cause this selection. Little to no impact of TCS was observed on intI1 relative abundance. Microbial communities were also surveyed by high-throughput 16S rRNA gene sequencing. Compared to the control digesters, significant shifts in community structure towards clades containing commensal and pathogenic bacteria were observed in digesters containing TCS. Based on these results, TCS should be included in studies and risk assessments that attempt to elucidate relationships between chemical stressors (e.g. antibiotics), antibiotic resistance genes, and public health

Multimodal spatial mapping and visualisation of Dinaledi Chamber and Rising Star Cave

The Dinaledi Chamber of the Rising Star Cave has yielded 1550 identifiable fossil elements – representing the largest single collection of fossil hominin material found on the African continent to date. The fossil chamber in which Homo naledi was found was accessible only through a near-vertical chute that presented immense practical and methodological limitations on the excavation and recording methods that could be used within the Cave. In response to practical challenges, a multimodal set of recording and survey methods was thus developed and employed: (1) recording of fossils and the excavation process was achieved through the use of white-light photogrammetry and laser scanning; (2) mapping of the Dinaledi Chamber was accomplished by means of high-resolution laser scanning, with scans running from the excavation site to the ground surface and the cave entrance; (3) at ground surface, the integration of conventional surveying techniques as well as photogrammetry with the use of an unmanned aerial vehicle was applied. Point cloud data were used to provide a centralised and common data structure for conversion and to corroborate the influx of different data collection methods and input formats. Data collected with these methods were applied to the excavations, mapping and surveying of the Dinaledi Chamber and the Rising Star Cave. This multimodal approach provides a comprehensive spatial framework from individual bones to landscape level

Enhanced ordering reduces electric susceptibility of liquids confined to graphene slit pores.

The behaviours of a range of polar and non-polar organic liquids (acetone, ethanol, methanol, N-methyl-2-pyrrolidone (NMP), carbon tetrachloride and water) confined to 2D graphene nanochannels with thicknesses in the range of 4.5 Å to 40 Å were studied using classical molecular dynamics and hybrid density functional theory. All liquids were found to organise spontaneously into ordered layers parallel to the confining surfaces, with those containing polar molecules having their electric dipoles aligned parallel to such surfaces. In particular, monolayers of NMP showed remarkable in-plane ordering and low molecular mobility, suggesting the existence of a previously unknown 2D solid-like phase. Calculations for polar liquids showed dramatically reduced static permittivities normal to the confining surfaces; these changes are expected to improve electron tunnelling across the liquid films, modifying the DC electrical properties of immersed assemblies of carbon nanomaterials.Mexican Council for Science and Technology (CONACyT)This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/srep2740

Metagenomics Reveal Triclosan-Induced Changes in the Antibiotic Resistome of Anaerobic Digesters

Triclosan (TCS) is a broad-spectrum antimicrobial used in a variety of consumer products. While it was recently banned from hand soaps in the US, it is still a key ingredient in a top-selling toothpaste. TCS is a hydrophobic micropollutant that is recalcitrant under anaerobic digestion thereby resulting in high TCS concentrations in biosolids. The objective of this study was to determine the impact of TCS on the antibiotic resistome and potential cross-protection in lab-scale anaerobic digesters using shotgun metagenomics. It was hypothesized that metagenomics would reveal selection for antibiotic resistance genes (ARGs) not previously found in pure culture studies or mixed-culture studies using targeted qPCR. In this study, four different levels of TCS were continuously fed to triplicate lab-scale anaerobic digesters to assess the effect of TCS levels on the antibiotic resistance gene profiles (resistome). Blasting metagenomic reads against antibiotic/metal resistance gene database (BacMet) revealed that ARG diversity and abundance changed along the TCS concentration gradient. While loss of bacterial diversity and digester function were observed in the digester treated with the highest TCS concentration, FabV, which is a known TCS resistance gene, increased in this extremely high TCS environment. The abundance of several other known ARG or metal resistance genes (MRGs), including corA and arsB, also increased as the concentrations of TCS increased. Analysis of other functional genes using SEED database revealed the increase of potentially key genes for resistance including different types of transporters and transposons. These results indicate that antimicrobials can alter the abundance of multiple resistance genes in anaerobic digesters even when function (i.e. methane production) is maintained. This study also suggests that enriched ARGs could be released into environments with biosolids land application