Search

Abstract Trillion of cigarette butts are annually littered without being recycled. This work aims at valorizing the whole cigarette butts and their components (paper, filter and tobacco) into Fe‐Nx‐C electrocatalysts for oxygen reduction reaction (ORR) in acid and alkaline media. The pristine wastes were pyrolyzed at 450 °C, activated with KOH at 700 °C, blended with iron phthalocyanine (FePc) precursor, and heat‐treated at 600 °C to produce a robust Fe‐Nx‐C material with ORR active units. The effect of the cigarette components on the final electrocatalytic activity was evaluated by thoroughly investigating the surface chemistry with XPS. The electrocatalysts displayed similar results among the different components in both media due to comparable surface chemistry, especially concerning the nitrogen functional groups. The highest performance was obtained in alkaline where the electrocatalysts from whole cigarettes and paper (CIGF_450 and CIGPF_450) showed an E1/2 of 0.89 V vs RHE, slightly larger than that of Pt/C with 40 wt % of Pt, which encouraged to replace Pt‐based electrocatalysts in alkaline fuel cells.

Abstract Background The Kuril–Kamchatka Trench (maximum depth 9604 m), located in the NW Pacific Ocean, is among the top seven deepest hadal trenches. The work aimed to investigate the unexplored abyssal-hadal prokaryotic communities of this fascinating, but underrated environment. Results As for the bacterial communities, we found that Proteobacteria (56.1–74.5%), Bacteroidetes (6.5–19.1%), and Actinobacteria (0.9–16.1%) were the most represented bacterial phyla over all samples. Thaumarchaeota (52.9–91.1%) was the most abundant phylum in the archaeal communities. The archaeal diversity was highly represented by the ammonia-oxidizing Nitrosopumilus, and the potential hydrocarbon-degrading bacteria Acinetobacter, Zhongshania, and Colwellia were the main bacterial genera. The α-diversity analysis evidenced that both prokaryotic communities were characterized by low evenness, as indicated by the high Gini index values (> 0.9). The β-diversity analysis (Redundancy Analysis) indicated that, as expected, the depth significantly affected the structure of the prokaryotic communities. The co-occurrence network revealed seven prokaryotic groups that covaried across the abyssal-hadal zone of the Kuril–Kamchatka Trench. Among them, the main group included the most abundant archaeal and bacterial OTUs (Nitrosopumilus OTU A2 and OTU A1; Acinetobacter OTU B1), which were ubiquitous across the trench. Conclusions This manuscript represents the first attempt to characterize the prokaryotic communities of the KKT abyssal-hadal zone. Our results reveal that the most abundant prokaryotes harbored by the abyssal-hadal zone of Kuril–Kamchatka Trench were chemolithotrophic archaea and heterotrophic bacteria, which did not show a distinctive pattern distribution according to depth. In particular, Acinetobacter, Zhongshania, and Colwellia (potential hydrocarbon degraders) were the main bacterial genera, and Nitrosopumilus (ammonia oxidizer) was the dominant representative of the archaeal diversity.

Diesel contamination of farming soils is of great concern because hydrocarbons are toxic to all forms of life and can potentially enter the food web through crops or plants used for remediation. Data on plant ability to uptake, translocate and accumulate diesel-derived compounds are controversial not only due to the probable diverse attitude of plant species but also because of the lack of a reliable method with which to distinguish petrogenic from biogenic compounds in plant tissues. The purpose of this study was to set up a GC-MS-based protocol enabling the determination of diesel-derived hydrocarbons in plants grown in contaminated soil for assessing human and ecological risks, predicting phytoremediation effectiveness and biomass disposal. To this end, two plant species, Vicia sativa L. and Secale cereale L., belonging to two diverse vascular plant families, were used as plant models. They were grown in soil spiked with increasing concentrations of diesel fuel, and the produced biomass was used to set up the hydrocarbon extraction and GC-MSD analysis. The developed protocol was also applied to the analysis of Typha latifolia L. plants, belonging to a different botanical family and grown in a long-time and highly contaminated natural soil. Results showed the possibility of distinguishing diesel-derived compounds from biogenic hydrocarbons in most terrestrial vascular plants, just considering the total diesel compounds in the n-alkanes carbon range C10–C26, where the interference of biogenic compounds is negligible. Diesel hydrocarbons quantification in plant tissues was strongly correlated (0.92 < r2 < 0.99) to the concentration of diesel in spiked soils, suggesting a general ability of the considered plant species to adsorb and translocate relatively low amounts of diesel hydrocarbons and the reliability of the developed protocol.

The Kuril–Kamchatka Trench (North-West Pacific Ocean) is included in the deepest trenches (>9000 m). This study is the first that aims at uncovering the bathyal prokaryotic diversity (1000–2000 m) of this fascinating extreme environment. The analysis of α-diversity revealed that bacterial communities showed greater diversity than archaeal communities and that both communities were characterized by poor evenness (indicative of the presence of few dominant OTUs). The metabarcoding analysis showed that Proteobacteria (65.5–90.7%), Bacteroidetes (2.4–10.7%), and Actinobacteria (2.5–9.6%) were the highly represented phyla of bacteria, with Acinetobacter (21.5–62.5%) as the most abundant genus. Moreover, the recently described Pseudofrancisella genus, which has been isolated from estuarine environments, has been found among the major bacterial taxa. This work represents the first report stating the presence of this genus in bathyal waters. The archaeal communities were dominated by the phylum Thaumarchaeota (53.6–94.0%), with Nitrosopumilus (53.6–94%) as its representative genus. The functional diversity analysis revealed that overall, the bacterial communities had a higher involvement in the carbon and nitrogen biogeochemical cycles, with chemoheterotrophy (mostly aerobic), aromatic compound degradation, and nitrate reduction as the most represented functions. In the archaeal communities, the most represented ecological function was the aerobic oxidation of ammonia (first stage of nitrification), a functional feature characteristic of Nitrosopumilus.

Background Microbial communities are found on any part of animal bodies exposed to the environment, and are particularly prominent in the gut, where they play such a major role in the host metabolism and physiology to be considered a “second genome”. These communities, collectively known as “microbiome”, are well studied in humans and model species, while studies on wild animals have lagged behind. This is unfortunate, as different studies suggested the central role of the gut microbiome in shaping the evolutionary trajectories of species and their population dynamics. Among bird species, only few descriptions of raptor gut microbiomes are available, and mainly carried out on captive individuals. Objectives In this study, we aimed at improving the knowledge of raptor microbiomes by providing the first description of the gut microbiome of the lesser kestrel (Falco naumanni), a cavity-nesting raptor. Results The gut microbiome of the lesser kestrel was dominated by Actinobacteria (83.9%), Proteobacteria (8.6%) and Firmicutes (4.3%). We detected no differences in microbiome composition between males and females. Furthermore, the general composition of the microbiome appears similar to that of phylogenetically distant cavity-nesting species. Conclusions Our results broaden the knowledge of raptor gut microbial communities and let us hypothesize that the distinct nest environment in terms of microclimate and presence of organic material from previous breeding attempts, to which cavity-nesting species that reuse the nest are exposed, might be an important driver shaping microbiomes.

Anthropic diesel-derived contamination of Mediterranean coastal waters is of great concern. Nature-based solutions such as phytoremediation are considered promising technologies to remove contaminants from marine environments. The aim of this work was to investigate the tolerance of the Mediterranean autochthonous seaweed Caulerpa prolifera (Forsskal) Lamouroux to diesel fuel and its hydrocarbon degradation potential. Changes in C. prolifera traits, including its associated bacterial community abundance and structure, were determined by fluorescence microscopy and next-generation sequencing techniques. Thalli of C. prolifera artificially exposed to increasing concentration of diesel fuel for 30 days and thalli collected from three natural sites with different levels of seawater diesel-derived hydrocarbons were analysed. Gas chromatography was applied to determine the seaweed hydrocarbon degradation potential. Overall, in controlled conditions the lower concentration of diesel (0.01%) did not affect C. prolifera survival and growth, whereas the higher concentration (1%) resulted in high mortality and blade damages. Similarly, only natural thalli, collected at the most polluted marine site (750 mg L−1), were damaged. A higher abundance of epiphytic bacteria, with a higher relative abundance of Vibrio bacteria, was positively correlated to the health status of the seaweed as well as to its diesel-degradation ability. In conclusion, C. prolifera tolerated and degraded moderate concentrations of seawater diesel-derived compounds, especially changing the abundance and community structure of its bacterial coating. The protection and exploitation of this autochthonous natural seaweed-bacteria symbiosis represents a useful strategy to mitigate the hydrocarbon contamination in moderate polluted Mediterranean costal environments.

Following the core theme of a circular economy, a novel strategy to upcycle cigarette butt waste into platinum group metal (PGM)-free metal nitrogen carbon (M-N-C) electrocatalysts for oxygen reduction reaction (ORR) is presented. The experimental route was composed of (i) the transformation of the powdered cigarette butts into carbonaceous char via pyrolysis at 450 °C, 600 °C, 750 °C and 900 °C, (ii) the porosity activation with KOH and (iii) the functionalization of the activated chars with iron (II) phthalocyanine (FePc). The electrochemical outcomes obtained by the rotating disk electrode (RRDE) technique revealed that the sample pyrolyzed at 450 °C (i.e., cig_450) outperformed the other counterparts with its highest onset (Eon) and half-wave potentials (E1/2) and demonstrated nearly tetra-electronic ORR in acidic, neutral and alkaline electrolytes, all resulting from the optimal surface chemistry and textural properties.

ABSTRACT Every year, deciduous trees shed their leaves, and when new leaves emerge next spring, they establish a characteristic bacterial leaf community. In this exploratory study, we assessed the bacterial phyllosphere (aboveground plant surfaces) of eight London plane trees (Platanus × acerifolia) in Antwerp and Milan by sampling weekly during leaf emergence and expansion. We sampled the surfaces of different tree compartments: leaves, leaf buds, branches, and trunk, for up to 6 weeks. Phyllosphere community composition was most strongly determined by tree compartment. Only the communities on the emerging leaves showed changing dynamics over time. The rate of change in the leaf phyllosphere composition, expressed as the beta dissimilarity between consecutive time points, was very high following leaf emergence, with decreasing speed over time, indicating that these communities stabilize over time. We also identified cooccurring groups of bacteria associated with potential stages of ecological succession on the leaves and accordingly named them general cluster, early cluster, middle cluster, and late cluster. Taxa of the general cluster were not only more abundant than the others on leaves, but they were also widespread on other tree compartments. The late cluster was most pronounced in trees surrounded by trafficked urban land use. This study mainly generates hypotheses on the ecological succession on the emerging leaves of deciduous trees in urban environments and contributes to understanding the development of the tree leaf phyllosphere in spring. IMPORTANCE Improving our understanding of phyllosphere ecology is key in successfully applying bacterial biological agents or modulating the leaf microbiome in order to achieve valuable ecosystem services, such as plant protection, plant growth, air purification, and developing a healthy human immune system. Modulation of the phyllosphere microbiome in the field works only with variable success. To improve the impact of our applications in the field, a better understanding of the ecological principles governing phyllosphere dynamics is required. This exploratory study demonstrates how the combination of different analyses of a chronosequence of bacterial communities can provide new ecological insights. With a limited number of sampled trees, we demonstrated different indications of ecological succession of bacterial communities in the leaves and observed a potential impact of intensely trafficked land use becoming apparent in the leaf bacterial communities approximately 3 weeks after leaf emergence, consisting of a separate stage in community development.

Insights into biodiversity and trophic webs are important for understanding ecosystem functions. Although the surfaces of glaciers are one of the most productive and biologically diverse parts of the cryosphere, the links between top consumers, their diet and microbial communities are poorly understood. In this study, for the first time we investigated the relationships between bacteria, fungi and other microeukaryotes as they relate to tardigrades, microscopic metazoans that are top consumers in cryoconite, a biologically rich and productive biogenic sediment found on glacier surfaces. Using metabarcoding (16S rDNA for bacteria, ITS1 for fungi, and 18S rDNA for other microeukaryotes), we analyzed the microbial community structures of cryoconite and compared them with the community found in both fully fed and starved tardigrades. The community structure of each microbial group (bacteria, fungi, microeukaryotes) were similar within each host group (cryoconite, fully fed tardigrades and starved tardigrades), and differed significantly between groups, as indicated by redundancy analyses. The relative number of operational taxonomic units (ZOTUs, OTUs) and the Shannon index differed significantly between cryoconite and tardigrades. Species indicator analysis highlighted a group of microbial taxa typical of both fully fed and starved tardigrades (potential commensals), like the bacteria of the genera Staphylococcus and Stenotrophomonas, as well as a group of taxa typical of both cryoconite and fully fed tardigrades (likely part of the tardigrade diet; bacteria Flavobacterium sp., fungi Preussia sp., algae Trebouxiophyceae sp.). Tardigrades are consumers of bacteria, fungi and other microeukaryotes in cryoconite and, being hosts for diverse microbes, their presence can enrich the microbiome of glaciers.

Electroactive bacteria have a wide range of applications, including electricity production, bioremediation, and the sensing of toxic compounds. Bacterial biofilm formation is often mediated by the second messenger cyclic guanosine monophosphate (c-di-GMP) synthesized by a diguanylate cyclase (DGC). The role of c-di-GMP in the expression of c-type cytochromes has been previously reported. The aim of this study was to determine the bioelectrogenic activity of Cupriavidus metallidurans strain CH34 pJBpleD*, which possesses a constitutively active DGC that increases c-di-GMP levels. Notably, the heterologous expression of the constitutively active DGC in C. metallidurans strain CH34 pJBpleD* showed a higher biofilm formation and increased the electrical current production up to 560%. In addition, C. metallidurans CH34 pJBpleD* showed increased levels of c-type cytochrome-associated transcripts compared with the wild-type strain CH34. Scanning electron microscopies revealed a denser extracellular matrix with an increased exopolymeric substance content in the CH34 pJBpleD* biofilm on the electrode surface. The results of this study suggest that higher levels of c-di-GMP synthesized by a constitutively active diguanylate cyclase in C. metallidurans strain CH34 pJBpleD* activated the formation of an electroactive biofilm on the electrode, enhancing its exoelectrogenic activity.

Snow can be considered an independent ecosystem that hosts active microbial communities. Snow microbial communities have been extensively investigated in the Arctic and in the Antarctica, but rarely in mid-latitude mountain areas. In this study, we investigated the bacterial communities of snow collected in four glacierized areas (Alps, Eastern Anatolia, Karakoram and Himalaya) by high-throughput DNA sequencing. We also investigated the origin of the air masses that produced the sampled snowfalls by reconstructing back-trajectories. A standardized approach was applied to all the analyses in order to ease comparison among different communities and geographical areas. The bacterial communities hosted from 25 to 211 Operational Taxonomic Units (OTUs), and their structure differed significantly between geographical areas. This suggests that snow bacterial communities may largely derive from ‘local’ air bacteria, maybe by deposition of airborne particulate of local origin that occurs during snowfall. However, some evidences suggest that a contribution of bacteria collected during air mass uplift to snow communities cannot be excluded, particularly when the air mass that originated the snow event is particularly rich in dust.

Cryoconite holes are small depressions of the glacier surface filled with melting water and with a wind-blown debris on the bottom. These environments are considered hot spots of biodiversity and biological activities on glaciers and host communities dominated by bacteria. Most of the studies on cryoconite holes assume that their communities are stable. However, evidence of seasonal variation in cryoconite hole ecological communities exists. We investigated the variation of the bacterial communities of cryoconite holes of Forni Glacier (Central Italian Alps) during the melting seasons (July–September) 2013 and 2016, for which samples at three and five time-points, respectively were available. Bacterial communities were characterized by high-throughput Illumina sequencing of the hypervariable V5−V6 regions of 16S rRNA gene, while meteorological data were obtained by an automatic weather station. We found consistent trends in bacterial communities, which shifted from cyanobacteria-dominated communities in July to communities dominated by heterotrophic orders in late August and September. Temperature seems also to affect seasonal dynamics of communities. We also compared bacterial communities at the beginning of the melting season across 4 years (2012, 2013, 2015 and 2016) and found significant year-to-year variability. Cryoconite hole communities on temperate glaciers are therefore not temporally stable.

The Museo Nazionale della Scienza e della Tecnologia "Leonardo da Vinci" in Milan is exposing two pairs of canal lock gates, used to control the water flow in Milan canal system, whose design appears in the Leonardo's Codex Atlanticus. The wood present in the gates has been deeply characterised by mean of a multidisciplinary investigation involving i) DNA barcoding of wood fragments; ii) microbial community characterisation, and iii) chemical analyses. DNA barcoding revealed that two fragments of the gates belonged to wood species widely used in the middle age: Fagus sylvatica and Picea abies. The chemical characterisations were based on the use of ionic liquid as dissolving medium in order to analyse the entire cell wall material by means of Gel Permeation Chromatography (GPC) and 2D-NMR-HSQC techniques. This multidisciplinary analytical approach was able to highlight the complex nature of the degradation occurred during the gate operation (XVI-XVIII centuries): an intricate interplay between microbial populations (i.e. Shewanella), inorganic factors (i.e. iron from nails), physical factors and the lignocellulosic material.

(1) Background: The surveillance of SARS-CoV-2 RNA in urban wastewaters allows one to monitor the presence of the virus in a population, including asymptomatic and symptomatic individuals, capturing the real circulation of this pathogen. The aim of this study was to evaluate the performance of different pre-analytical and analytical methods for identifying the presence of SARS-CoV-2 in untreated municipal wastewaters samples by conducting an inter-laboratory proficiency test. (2) Methods: three methods of concentration, namely, (A) Dextran and PEG-6000 two-phase separation, (B) PEG-8000 precipitation without a chloroform purification step and (C) PEG-8000 precipitation with a chloroform purification step were combined with three different protocols of RNA extraction by using commercial kits and were tested by using two primers/probe sets in three different master mixes. (3) Results: PEG-8000 precipitation without chloroform treatment showed the best performance in the SARS-CoV-2 recovery; no major differences were observed among the protocol of RNA extraction and the one-step real-time RT-PCR master mix kits. The highest analytic sensitivity was observed by using primers/probe sets targeting the N1/N3 fragments of SARS-CoV-2. (4) Conclusions: PEG-8000 precipitation in combination with real-time RT-PCR targeting the N gene (two fragments) was the best performing workflow for the detection of SARS-CoV-2 RNA in municipal wastewaters.

Have you ever sought to use metagenomic DNA sequences reported in scientific publications? Were you successful? Here, we reveal that metagenomes from no fewer than 20% of the papers found in our literature search, published between 2016 and 2019, were not deposited in a repository or were simply inaccessible. The proportion of inaccessible data within the literature has been increasing year-on-year. Noncompliance with Open Data is best predicted by the scientific discipline of the journal. The number of citations, journal type (e.g., Open Access or subscription journals), and publisher are not good predictors of data accessibility. However, many publications in high-impact factor journals do display a higher likelihood of accessible metagenomic data sets. Twenty-first century science demands compliance with the ethical standard of data sharing of metagenomes and DNA sequence data more broadly. Data accessibility must become one of the routine and mandatory components of manuscript submissions-a requirement that should be applicable across the increasing number of disciplines using metagenomics. Compliance must be ensured and reinforced by funders, publishers, editors, reviewers, and, ultimately, the authors.

Most of the world’s mountain glaciers have been retreating for more than a century in response to climate change. Glacier retreat is evident on all continents, and the rate of retreat has accelerated during recent decades. Accurate, spatially explicit information on the position of glacier margins over time is useful for analyzing patterns of glacier retreat and measuring reductions in glacier surface area. This information is also essential for evaluating how mountain ecosystems are evolving due to climate warming and the attendant glacier retreat. Here, we present a non-comprehensive spatially explicit dataset showing multiple positions of glacier fronts since the Little Ice Age (LIA) maxima, including many data from the pre-satellite era. The dataset is based on multiple historical archival records including topographical maps; repeated photographs, paintings, and aerial or satellite images with a supplement of geochronology; and own field data. We provide ESRI shapefiles showing 728 past positions of 94 glacier fronts from all continents, except Antarctica, covering the period between the Little Ice Age maxima and the present. On average, the time series span the past 190 years. From 2 to 46 past positions per glacier are depicted (on average: 7.8).

Enterobacteriaceae is present in various niches worldwide (i.e., the gastrointestinal tracts of animals, clinical specimens, and diverse environments) and hosts some well-known pathogens (i.e., salmonellas, shigellas and pathogenic coliforms). No investigation has focused on its occurrence in marine salterns, and it is not clear if these hypersaline environments could be a reservoir for these bacteria including some potentially harmful members. In this study, a two-year metabarcoding survey was carried out on samples collected from different ponds of the “Saline di Tarquinia” salterns and the nearby coastal waters. Enterobacteriaceae was recorded almost constantly in the seawaters feeding the saltern. Its abundance was generally higher in the sea than in the ponds, probably due to the higher anthropic impact. The same trend was evidenced for the key genus (Escherichia/Shigella) and OTU (OTU 5) of the Enterobacteriaceae community. Various parameters affected taxon/OTU abundance: Enterobacteriaceae, Escherichia/Shigella and OTU5 decreased with increasing salinity and rains; moreover, Escherichia/Shigella and OTU 5 were higher in autumn than in spring. Although Enterobacteriaceae did not seem to find the most favourable conditions for a high-abundance persistence in the saltern environment, it did not disappear. These observations suggested this environment as a potential reservoir for bacteria with possible important health implications.

The “Saline di Tarquinia” salterns have been scarcely investigated regarding their microbiological aspects. This work studied the structure and composition of their bacterial communities along the salinity gradient (from the nearby sea through different ponds). The communities showed increasing simplification of pond bacterial diversity along the gradient (particularly if compared to those of the sea). Among the 38 assigned phyla, the most represented were Proteobacteria, Actinobacteria and Bacteroidetes. Differently to other marine salterns, where at the highest salinities Bacteroidetes dominated, preponderance of Proteobacteria was observed. At the genus level the most abundant taxa were Pontimonas, Marivita, Spiribacter, Bordetella, GpVII and Lentibacter. The α-diversity analysis showed that the communities were highly uneven, and the Canonical Correspondence Analysis indicated that they were structured by various factors (sampling site, sampling year, salinity, and sampling month). Moreover, the taxa abundance variation in relation to these significant parameters were investigated by Generalized Linear Models. This work represents the first investigation of a marine saltern, carried out by a metabarcoding approach, which permitted a broad vision of the bacterial diversity, covering both a wide temporal span (two years with monthly sampling) and the entire salinity gradient (from the nearby sea up to the crystallisation ponds).

Groundwater is the environmental matrix that is most frequently affected by anthropogenic hexavalent chromium contamination. Due to its carcinogenicity, Cr(VI) has to be removed, using environmental-friendly and economically sustainable remediation technologies. BioElectrochemical Systems (BESs), applied to bioremediation, thereby offering a promising alternative to traditional bioremediation techniques, without affecting the natural groundwater conditions. Some bacterial families are capable of oxidizing and/or reducing a solid electrode obtaining an energetic advantage for their own growth. In the present study, we assessed the possibility of stimulating bioelectrochemical reduction of Cr(VI) in a dual-chamber polarized system using an electrode as the sole energy source. To develop an electroactive microbial community three electrodes were, at first, inserted into the anodic compartment of a dual-chamber microbial fuel cell, and inoculated with sludge from an anaerobic digester. After a period of acclimation, one electrode was transferred into a polarized system and it was fixed at −0.3 V (versus standard hydrogen electrode, SHE), to promote the reduction of 1000 µg Cr(VI) L−1. A second electrode, served for the set-up of an open circuit control, operated in parallel. Cr(VI) dissolved concentration was analysed at the initial, during the experiment and final time by spectrophotometric method. Initial and final microbial characterization of the communities enriched in polarized system and open circuit control was performed by 16S rRNA gene sequencing. The bioelectrode set at −0.3 V showed high Cr(VI) removal efficiency (up to 93%) and about 150 µg L−1 day−1 removal rate. Similar efficiency was observed in the open circuit (OC) even at about half rate. Whereas, purely electrochemical reduction, limited to 35%, due to neutral operating conditions. These results suggest that bioelectrochemical Cr(VI) removal by polarized electrode offers a promising new and sustainable approach to the treatment of groundwater Cr(VI) plumes, deserving further research.

Bioelectrochemical systems (BESs) exploit the interaction between microbes and electrodes. A field of application thereof is bioelectrochemical remediation, an effective strategy in environments where the absence of suitable electron acceptors limits classic bioremediation approaches. Understanding the microbial community structure and genetic potential of anode biofilms is of great interest to interpret the mechanisms occurring in BESs. In this study, by using a whole metagenome sequencing approach, taxonomic and functional diversity patterns in the inoculum and on the anodes of three continuous-flow BES for the removal of phenol, toluene, and BTEX were obtained. The genus Geobacter was highly enriched on the anodes and two reconstructed genomes were taxonomically related to the Geobacteraceae family. To functionally characterize the microbial community, the genes coding for the anaerobic degradation of toluene, ethylbenzene, and phenol were selected as genetic markers for the anaerobic degradation of the pollutants. The genes related with direct extracellular electron transfer (EET) were also analyzed. The inoculum carried the genetic baggage for the degradation of aromatics but lacked the capacity of EET while anodic bacterial communities were able to pursue both processes. The metagenomic approach provided useful insights into the ecology and complex functions within hydrocarbon-degrading electrogenic biofilms.

Background: Due to the amphipathic properties of biosurfactants which act on surfaces and interfaces interest by a variety of industries such as cosmetic, pharmaceutical, bioremediation and petroleum-related industries has recently increased. Methods: Detection of a high-efficiency biosurfactant producer using preliminary screening methods from soil contaminated with crude oil was carried at the Microbiology Laboratory at Shahid Beheshti University, Tehran, Iran in 2013. Then after characterization of some physico-chemical properties of produced biosurfactant and production optimization conditions, processes of purification and complete identification were done. Results: Pseudomonas aeruginosa sp. ZN was selected as high-efficiency biosurfactant producing strain from soil contaminated with oil from Ahvaz City, Khuzestan Province, southern Iran. The biosurfactant production in modified BH2 culture medium supplemented with 1% n-hexadecane occurred during exponential phase resulting in a reduction surface tension from 70 to 29 mN/m. Strain ZN produced biosurfactant with different properties to other Pseudomonas reported. These characterizations included continued production at C/N ratio range of 10-40; the produced biosurfactant could not separate stable emulsion of span-80-kerosene: Tween-80-distilled water (30:70) within 24 h. The produced biosurfactants were able to increase hydrophobicity of bacterial cell to 55%. Recovery of biosurfactants from cell-free supernatant was performed with acid precipitation and ammonium sulfate precipitation. Chemical analysis such as spraying techniques on developed TLC plate and staining methods of supernatant indicated that produced biosurfactants were glycolipids, characterized by ESI-MS analysis of extracted product as di-rhamnolipids. Conclusion: Ability of this strain to produce biosurfactant in the presence of cooked oil and n-hexadecane make it an optimistic candidate for biodegradation of some derivatives of crude oil and food industry.

We investigated the potential contribution of ice-marginal environments to the microbial communities of cryoconite holes, small depressions filled with meltwater that form on the surface of Forni Glacier (Italian Alps). Cryoconite holes are considered the most biologically active environments on glaciers. Bacteria can colonize these environments by short-range transport from ice-marginal environments or by long-range transport from distant areas. We used high throughput DNA sequencing to identify Operational Taxonomic Units (OTUs) present in cryoconite holes and three ice-marginal environments, the moraines, the glacier forefield, and a large (> 3 m high) ice-cored dirt cone occurring on the glacier surface. Bacterial communities of cryoconite holes were different from those of ice-marginal environments and hosted fewer OTUs. However, a network analysis revealed that the cryoconite holes shared more OTUs with the moraines and the dirt cone than with the glacier forefield. Ice-marginal environments may therefore act as sources of bacteria for cryoconite holes, but differences in environmental conditions limit the number of bacterial strains that may survive in them. At the same time, cryoconite holes host a few OTUs that were not found in any ice-marginal environment we sampled, thus suggesting that some bacterial populations are positively selected by the specific environmental conditions of the cryoconite holes.

Chromium is one of the most frequently used metal contaminants. Its hexavalent form Cr(VI), which is exploited in many industrial activities, is highly toxic, is water-soluble in the full pH range, and is a major threat to groundwater resources. Alongside traditional approaches to Cr(VI) treatment based on physical-chemical methods, technologies exploiting the ability of several microorganisms to reduce toxic and mobile Cr(VI) to the less toxic and stable Cr(III) form have been developed to improve the cost-effectiveness and sustainability of remediating hexavalent chromium-contaminated groundwater. Bioelectrochemical systems (BESs), principally investigated for wastewater treatment, may represent an innovative option for groundwater remediation. By using electrodes as virtually inexhaustible electron donors and acceptors to promote microbial oxidation-reduction reactions, in in situ remediation, BESs may offer the advantage of limited energy and chemicals requirements in comparison to other bioremediation technologies, which rely on external supplies of limiting inorganic nutrients and electron acceptors or donors to ensure proper conditions for microbial activity. Electron transfer is continuously promoted/controlled in terms of current or voltage application between the electrodes, close to which electrochemically active microorganisms are located. Therefore, this enhances the options of process real-time monitoring and control, which are often limited in in situ treatment schemes. This paper reviews research with BESs for treating chromium-contaminated wastewater, by focusing on the perspectives for Cr(VI) bioelectrochemical remediation and open research issues.

Two by-products containing phenols and polysaccharides, a “pâté” (OP) from the extra virgin olive oil milling process and a decoction of pomegranate mesocarp (PM), were investigated for their effects on human microbiota using the SHIME® system. The ability of these products to modulate the microbial community was studied simulating a daily intake for nine days. Microbial functionality, investigated in terms of short chain fatty acids (SCFA) and NH4+, was stable during the treatment. A significant increase in Lactobacillaceae and Bifidobacteriaceae at nine days was induced by OP mainly in the proximal tract. Polyphenol metabolism indicated the formation of tyrosol from OP mainly in the distal tract, while urolithins C and A were produced from PM, identifying the human donor as a metabotype A. The results confirm the SHIME® system as a suitable in vitro tool to preliminarily investigate interactions between complex botanicals and human microbiota before undertaking more challenging human studies.

Widespread pollution of terrestrial ecosystems with petroleum hydrocarbons (PHCs) has generated a need for remediation and, given that many PHCs are biodegradable, bio- and phyto-remediation are often viable approaches for active and passive remediation. This review focuses on phytoremediation with particular interest on the interactions between and use of plant – associated bacteria to restore PHC polluted sites. Plant-associated bacteria include endophytic, phyllospheric and rhizospheric bacteria, and cooperation between these bacteria and their host plants allows for greater plant survivability and treatment outcomes in contaminated sites. Bacterially-driven PHC bioremediation is attributed to the presence of diverse suites of metabolic genes for aliphatic and aromatic hydrocarbons, along with a broader suite of physiological properties including biosurfactant production, biofilm formation, chemotaxis to hydrocarbons, and flexibility in cell-surface hydrophobicity. In soils impacted by PHC contamination, microbial bioremediation generally relies on the addition of high-energy electron acceptors (e.g. oxygen) and fertilization to supply limiting nutrients (e.g. nitrogen, phosphorous, potassium) in the face of excess PHC carbon. As an alternative, the addition of plants can greatly improve bioremediation rates and outcomes as plants provide microbial habitats, improve soil porosity (thereby increasing mass transfer of substrates and electron acceptors), and exchange limiting nutrients with their microbial counterparts. In return, plant-associated microorganisms improve plant growth by reducing soil toxicity through contaminant removal, producing plant growth promoting metabolites, liberating sequestered plant nutrients from soil, fixing nitrogen, and more generally establishing the foundations of soil nutrient cycling. In a practical and applied sense, the collective action of plants and their associated microorganisms is advantageous for remediation of PHC contaminated soil in terms of overall cost and success rates for in situ implementation in a diversity of environments. Mechanistically, there remain biological unknowns that present challenges for applying bio- and phyto-remediation technologies without having a deep prior understanding of individual target sites. In this review, evidence from traditional and modern omics technologies is discussed to provide a framework for plant-microbe interactions during PHCs remediation. The potential for integrating multiple molecular and computational techniques to evaluate linkages between microbial communities, plant communities and ecosystem processes is explored with an eye on

Baltic Sea deep water and sediments hold one of the largest anthropogenically induced hypoxic areas in the world. High nutrient input and low water exchange result in eutrophication and oxygen depletion below the halocline. As a consequence at Landsort Deep, the deepest point of the Baltic Sea, anoxia in the sediments has been a persistent condition over the past decades. Given that microbial communities are drivers of essential ecosystem functions we investigated the microbial community metabolisms and functions of oxygen depleted Landsort Deep sediments by metatranscriptomics. Results show substantial expression of genes involved in protein metabolism demonstrating that the Landsort Deep sediment microbial community is active. Identified expressed gene suites of metabolic pathways with importance for carbon transformation including fermentation, dissimilatory sulphate reduction and methanogenesis were identified. The presence of transcripts for these metabolic processes suggests a potential for heterotrophic-autotrophic community synergism and indicates active mineralisation of the organic matter deposited at the sediment as a consequence of the eutrophication process. Furthermore, cyanobacteria, probably deposited from the water column, are transcriptionally active in the anoxic sediment at this depth. Results also reveal high abundance of transcripts encoding integron integrases. These results provide insight into the activity of the microbial community of the anoxic sediment at the deepest point of the Baltic Sea and its possible role in ecosystem functioning.