Stream hydrological fragmentation drives bacterioplankton community composition

In Mediterranean intermittent streams, the hydrological fragmentation in summer and the successive water flow reconvergence in autumn allow exploring how local processes shape the microbial community within the same habitat. The objectives of this study were to determine how bacterial community composition responded to hydrological fragmentation in summer, and to evaluate whether the seasonal shifts in community composition predominate over the effects of episodic habitat fragmentation. The bacterial community was assessed along the intermittent stream Fuirosos (Spain), at different levels of phylogenetic resolution by in situ hybridization, fingerprinting, and 16S rRNA gene sequencing. The hydrological fragmentation of the stream network strongly altered the biogeochemical conditions with the depletion of oxidized solutes and caused changes in dissolved organic carbon characteristics. In the isolated ponds, beta-Proteobacteria and Actinobacteria increased their abundance with a gradual reduction of the alpha-diversity as pond isolation time increased. Moreover, fingerprinting analysis clearly showed a shift in community composition between summer and autumn. In the context of a seasonal shift, the temporary stream fragmentation simultaneously reduced the microbial dispersion and affected local environmental conditions (shift in redox regime and quality of the dissolved organic matter) tightly shaping the bacterioplankton community composition

Quality and reactivity of dissolved organic matter in a Mediterranean river across hydrological and spatial gradients.

Understanding DOM transport and reactivity in rivers is essential to having a complete picture of the global carbon cycle. In this study, we explore the effects of hydrological variability and downstream transport on dissolved organic matter (DOM) dynamics in a Mediterranean river. We sampled the main stem of the river Tordera from the source to the sea, over a range of fifteen hydrological conditions including extreme events (flood and drought). By exploring spatial and temporal gradients of DOM fluorescence properties, river hydrology was found to be a significant predictor of DOM spatial heterogeneity. An additional space-resolved mass balance analysis performed on four contrasting hydrological conditions revealed that this was due to a shift in the biogeochemical function of the river. Flood conditions caused a conservative transport of DOM, generating a homogeneous, humic-like spatial profile of DOM quality. Lower flows induced a non-conservative, reactive transport of DOM, which enhanced the spatial heterogeneity of DOM properties. Moreover, the downstream evolution of DOM chemostatic behaviour revealed that the role of hydrology in regulating DOM properties increased gradually downstream, indicating an organised inter-dependency between the spatial and the temporal dimensions. Overall, our findings reveal that riverine DOM dynamics is in constant change owing to varying hydrological conditions, and emphasize that in order to fully understand the role of rivers in the global carbon cycle, it is necessary to take into account the full range of hydrological variability, from floods to droughts

Competition and protist predation are important regulators of riverine bacterial community composition and size distribution

Among the bacterivorous protists, heterotrophic nanoflagellates (HNFs) are considered to be the main grazers of bacteria in freshwaters due to their size-selective grazing. In this work, we assessed the change of a riverine bacterial community in controlled incubations, where HNFs' predation pressure was initially released through filtration. Filtration did not prevent the passage of cysts, which grew in the enrichments afterwards. Data on the composition of the bacterial community were gathered by Catalyzed Reporter Deposition Fluorescent In situ Hybridization (CARD-FISH) using 16S probes targeting phylogenetic groups. Bacterial cell size was also examined using image analysis. Overall, the initial filtration directly (through release of predation pressure) or indirectly (through competition among bacterial groups) affected the bacterial community composition. When nanoflagellate abundance rose, a reduction of bacterial abundance and changes in cell size distribution were observed. Gamma-Proteobacteria and Actinobacteria were the groups showing the greatest reduction in abundance. Beta-Proteobacteria showed a reduction of cell size and were found in aggregates. Alpha-Proteobacteria and Actinobacteria developed two distinct filamentous morphotypes: short, segmented rods and long chains of rods. Our results showed that the release of the predation pressure and the successive rise of the nanoflagellates changed the bacterial community in terms of composition at large phylogenetic scale. HNF grazing is highly group-specific and seems to reconstruct the community based on cell size, and thus, not only drastically changing the bacterial community composition, but also increasing its functional diversity

Enhancing methane production from food waste fermentate using biochar. The added value of electrochemical testing in pre-selecting the most effective type of biochar

Background: Recent studies have suggested that addition of electrically conductive biochar particles is an effective strategy to improve the methanogenic conversion of waste organic substrates, by promoting syntrophic associations between acetogenic and methanogenic organisms based on interspecies electron transfer processes. However, the underlying fundamentals of the process are still largely speculative and, therefore, a priori identification, screening, and even design of suitable biochar materials for a given biotechnological process are not yet possible. Results: Here, three charcoal-like products (i.e., biochars) obtained from the pyrolysis of different lignocellulosic materials, (i.e., wheat bran pellets, coppiced woodlands, and orchard pruning) were tested for their capacity to enhance methane production from a food waste fermentate. In all biochar-supplemented (25 g/L) batch experiments, the complete methanogenic conversion of fermentate volatile fatty acids proceeded at a rate that was up to 5 times higher than that observed in the unamended (or sand-supplemented) controls. Fluorescent in situ hybridization analysis coupled with confocal laser scanning microscopy revealed an intimate association between archaea and bacteria around the biochar particles and provided a clear indication that biochar also shaped the composition of the microbial consortium. Based on the application of a suite of physico-chemical and electrochemical characterization techniques, we demonstrated that the positive effect of biochar is directly related to the electron-donating capacity (EDC) of the material, but is independent of its bulk electrical conductivity and specific surface area. The latter properties were all previously hypothesized to play a major role in the biochar-mediated interspecies electron transfer process in methanogenic consortia. Conclusions: Collectively, these results of this study suggest that for biochar addition in anaerobic digester operation, the screening and identification of the most suitable biochar material should be based on EDC determination, via simple electrochemical tests. © 2017 The Author(s)

Bacterial uptake of DOM released from P-limited phytoplankton

The growth and the structure of a coastal bacterioplankton community were monitored in short-term bottle experiments in order to investigate the bacterial uptake of extracellular organic carbon released by the diatom Cylindrotheca closterium grown under P-balanced and P-depleted conditions. Bacterial specific growth rates and carbon demand were significantly lower in the exudates from P-depleted algae (24% and 30% reduction, respectively). The origin of the extracellular carbon appeared also to affect the taxonomic composition of the bacterioplankton assemblage, mainly reducing the development of Q-Proteobacteria. This pattern of bacterial carbon uptake could contribute to a longer persistence of the exudates released in P-depleted conditions affecting the dynamics of the carbon cycle in marine environments

Dissolved organic matter in continental hydro-geothermal systems: insights from two hot springs of the East African Rift valley

Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from continental geothermal systems, with only a few reports available from the Yellowstone US National Park. In this study, we explored the chemodiversity of DOM in water samples collected from two geothermal hot springs from the Kenyan East African Rift Valley, a region extremely rich in fumaroles, geysers, and spouting springs, located in close proximity to volcanic lakes. The DOM characterization included in-depth assessments performed by negative electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Reduced, saturated and little aromatic DOM compounds were dominant in the hot spring waters collected from either the Ol Njorowa gorge (ON) or the south shore of the soda-saline Lake Elementaita (ELM). Oxygen-poor and sulfur-bearing DOM molecules prevailed in ON, probably reflecting abiotic sulfurization from sulfide-rich geofluids. Nitrogen-bearing aliphatic and protein-like molecules were abundant in ELM, possibly perfusing through the organic-rich sediments of the adjacent Lake Elementaita. Notably, the heat-altered DOM of ancient autochthonous derivation could represent an overlooked source of aliphatic organic carbon for connected lentic environments, with a potential direct impact on nutrient cycling in lakes that receive geothermal water inputs

Evaluating resource sharing for offshore wind farm maintenance:The case of jack-up vessels

Offshore wind energy is recognised globally as a viable alternative to finite energy sources. However, large cost reductions are still needed, particularly in the Operations & Maintenance (O&M) phase, which currently accounts for about 30% of the cost of offshore wind. For large component replacements, a jack-up vessel is often leased from the spot market, resulting in high costs and low utilisation. These costs can be lowered when multiple wind farm service providers would share the resources needed to employ jack-up vessels. In this paper, we analyse two types of resource sharing, as an alternative to each service provider leasing its own vessel: (i) vessel purchasing and sharing and (ii) the combined use of vessel and harbour sharing. We design a simulation model and include stochastic processes such as weather patterns and component failures. Results show that cost benefits up to 45% can be achieved compared to a leasing policy, depending on the number of wind farm service providers involved and on the geographical distance between offshore wind farms. Moreover, it is shown that the jack-up vessel should not be fully utilised to minimise costs. The performance benefits of harbour sharing in addition to vessel sharing are generally small, but become more significant if the network faces considerable congestion. Results are illustrated using a case study based on a setting in the Western North Sea

Biogeochemical and microbial community structure differently modulates CO2 and CH4 dynamics in two adjacent volcanic lakes (Monticchio, Italy)

By hosting significant amounts of extra-atmospheric dissolved gases, including geogenic CO2 and CH4, volcanic lakes provide relevant ecosystem services through the key role the aquatic microbial community in mediating freshwater carbon fluxes. In view of elucidating the mechanisms governing the microbial spatial distribution and the possible implications for ecosystem functioning, we compared the hydrogeochemical features and the microbial community structure of two adjacent stratified volcanic lakes (Lake Grande - LG and Lake Piccolo - LP). Water chemistry, gases and their isotopic composition were coupled with microbial pigment profiling, cell counting, and phylogenetic analyses. LP showed transparent waters with low concentrations of chlorophyll-a and the occurrence of phycoerytrin-rich cyanobacteria. LG was relatively more eutrophic with a higher occurrence of diatoms and phycocyanine-rich cyanobacteria. Considering the higher concentrations of CO2 and CH4 in bottom waters, the oligotrophic LP was likely a more efficient sink of geogenic CO2 in comparison to the adjacent eutrophic LG. The prokaryotic community was dominated by the mixothrophic hgcI clade (family Sporichthyaceae) in the LG surface waters, while in LP this taxon was dominant down to -15 m. Moreover, in LP, the bottom dark waters harbored a unique strictly anaerobic bacterial assemblage associated with methanogenic Archaea (i.e. Methanomicrobiales), resulting in a high biogenic methane concentration. Water layering and light penetration were confirmed as major factors affecting the microbial distribution patterns. The observed differences in the geochemical and trophic conditions reflected the structure of the aquatic microbial community, with direct consequences on the dynamics of dissolved greenhouse gases

Italian Physicians' Perceptions about the Role of Asciminib in Later Lines Chronic Myeloid Leukemia in Clinical Practice: A GIMEMA Survey

Unmet needs remain in later lines chronic myeloid leukemia (CML): the response rate and the overall survival of resistant patients in the chronic phase who changed a second-generation TKI in the second line with another TKI with similar action are usually poor, while the off-target toxicities and the potential development of mutations increase. The recent approval of asciminib, a STAMP inhibitor, in the third line, has the potential to soon change the therapeutic algorithm for this subset of patients. Here, we report the results of a GIMEMA survey assessing the number of patients currently treated in the third line in Italy, the current approach in later lines by Italian physicians, and the future role of this drug according to the reason to switch to asciminib (resistance and/or intolerance), as well as the perceptions about the future position of this agent

P495: UNLOCKING THE POTENTIAL OF SYNTHETIC PATIENTS FOR ACCELERATING CLINICAL TRIALS: RESULTS OF THE FIRST GIMEMA EXPERIENCE

Background: Artificial intelligence is contributing to improve different medicine areas including clinical trial design. One field that holds a great potential is represented by the use of digital data as an alternative to real ones. The generation of a virtual cohort of patients might be advantageous since an artificial group of patients resembles the real dataset in all the key features but it does not include any identifiable real-patient data, tackling - by a privacy standpoint – the “burden” of collecting data subjects’ consent as well as the shortcomings of common anonymization techniques. Aims: To test the feasibility of this approach and evaluate its potential in clinical trial design, we built an in-silico cohort based on the large dataset of patients enrolled in the GIMEMA AML1310 study (Venditti et al. 2019), which entailed a “3 + 7”-like induction and a risk-adapted, MRD-directed post-remission transplant allocation. Methods: To create the synthetic cohort of patients, a machine learning generative model was constructed from the real individual-level data of the AML1310 study, capturing its patterns and statistical properties. AML1310 enrolled 500 patients (median age 49 years old) in 55 GIMEMA Institutions. All patients were NCCN2009 risk classified and analyzed by morphology, cytogenetics, molecular biology and multiparametric flow cytometry. The subset of 445 patients with ELN2017 risk classification available was used. To this purpose, the R package “synthpop” was used considering a parametric method: for binary data the logistic regression, for a factor with > 2 levels the polytomous logistic regression, for an ordered factor with > 2 levels the ordered polytomous logistic regression. For time to event variables the classification and regression trees method was used. Next, we verified the adherence of the virtual cohort to the original one in terms of age, gender, PS, WBC count, FLT3 and NPM1 mutations, risk category, CR achievement, MRD, transplant rate. Virtual and real cohorts were also compared in terms of survival outcomes. Results: By using the real-patient dataset from the AML1310 trial, a virtual cohort of 850 patients, named synthAML1310, was generated. By comparing the two cohorts, we observed that the clinico-biological characteristics and response evaluations (CR and MRD rates) did not differ significantly. Moreover, as depicted in Figure 1, the curves of OS and DFS were superimposable. Indeed, at 2 years, OS was 57% (52.5%-61.9%) in the original and 59.1% (55.9%-62.6%) in the synthAML1310 cohort. DFS was 55.1% (49.8%-60.9%) in the original and 55.1% (51.3%-59.2%) in the synthetic cohort. Summary/Conclusion: These results demonstrate the success of this approach in producing a virtual dataset that perfectly mimics the original and that, from a “privacy by design” perspective, minimizes the risk of re-identification of patients. Mirroring an AML population treated with a conventional chemotherapeutic approach, synthAML1310 is suitable to represent the control group when testing novel innovative treatments, most likely in an in-silico randomized trial, but also in other settings like propensity score matching analyses in observational studies. Shifting to an in-silico trial would overcome the challenges of randomized trials and it would be beneficial also for patients. since, they would receive only the experimental treatment without being exposed to the “less active“ therapy, thus limiting treatment failures and toxicity. Also, enrolment and the attainment of final results would be faster