Geographical variability of bacterial communities of cryoconite holes of Andean glaciers

Cryoconite holes, ponds full of melting water with sediment on the bottom, are hotspots of biodiversity on glacier surfaces and host dynamic micro-ecosystems. They have been extensively investigated in different areas of the world (e.g., the Arctic, Antarctic, Alps, and Himalaya), but so far no study has described the bacterial communities of the glaciers in the Andes, the world's longest mountain range. In this study, we describe the bacterial communities of three small (< 2 km²) high-elevation (< 4200 m a.s.l.) glaciers of the Central Andes (Iver, East Iver and Morado glaciers) and two large (> 85 km²) glaciers of the Patagonian Andes (Exploradores and Perito Moreno glaciers) whose ablation tongues reach low altitude (< 300 m a.s.l.). Results show that the bacterial communities were generally similar to those observed in the cryoconite holes of other continents, but with few cyanobacteria (0.5% of sequences). The most abundant orders were Betaproteobacteriales, Cytophagales, Chitinophagales, Acetobacterales, Frankiales, Armatimonadales, Sphingobacteriales, Rhizobiales, Bacteroidales, Sphingomonadales, and Micrococcales. The bacterial communities differed between glaciers and both water pH and O₂ concentration appeared to influence the bacterial community composition. This work thus provides the first description of the bacterial communities in cryoconite holes of South American glaciers.

Early ecological succession patterns of bacterial, fungal and plant communities along a chronosequence in a recently deglaciated area of the Italian Alps

In this study, the early ecological succession patterns of Forni Glacier (Ortles-Cevedale group, Italian Alps) forefield along an 18-year long chronosequence (with a temporal resolution of 1 year) has been reported. Bacterial and fungal community structures were inferred by high-throughput sequencing of 16S rRNA gene and ITS, respectively. In addition, the occurrence of both herbaceous and arboreous plants was also recorded at each plot. A significant decrease of alpha-diversity in more recently deglaciated areas was observed for both bacteria and plants. Time since deglaciation and pH affected the structure of both fungal and bacterial communities. Pioneer plants could be a major source of colonization for both bacterial and fungal communities. Consistently, some of the most abundant bacterial taxa and some of those significantly varying with pH along the chronosequence (Polaromonas, Granulicella, Thiobacillus, Acidiferrobacter) are known to be actively involved in rock-weathering processes due to their chemolithotrophic metabolism, thus suggesting that the early phase of the chronosequence could be mainly shaped by the biologically controlled bioavailability of metals and inorganic compounds. Fungal communities were dominated by ascomycetous filamentous fungi and basidiomycetous yeasts. Their role as cold-adapted organic matter decomposers, due to their heterotrophic metabolism, was suggested.

Use of balloon catheter dilation and steroid-eluting stent in light and severe rhinosinusitis of frontal sinus: a multicenter retrospective randomized study

OBJECTIVE

Frontal sinus surgery has an increased rate of re-stenosis, if compared to other sinuses. It depends mainly on recurrent inflammation and abnormal scarring at the frontal recess and its reduction represents one of the keys to therapeutic success. Balloon catheter dilation (BCD) and implantable sinus stents/spacers represent strategies to improve sinus ventilation respecting the integrity of mucosa and reducing abnormal post-surgical scarring. The purpose of this study was to evaluate the effectiveness, safety and correct indication about the use of BCD and a non-absorbable stent (Relieva Stratus™ MicroFlow spacer) in the management of chronic rhinosinusitis (CRS) of the frontal sinus.

PATIENTS AND METHODS

In this multicentric retrospective study we included a population of 76 frontal sinuses with non-polypoid CRS. 41 frontal sinuses were treated with BCD alone and 35 frontal sinuses with BCD + Spacer. We analyzed both radiological (Lund-McKay CT scoring modified by Zinreich) and symptomatological results (SNOT-20 questionnaire) before surgery and after 12 months, dividing our population in two main groups: group "L" (light/mild frontal CRS) and group "S" (moderate/severe frontal CRS).

RESULTS

Our results confirm a good safety and effectiveness of BCD in the management of frontal CRS and show a good safety but a not significative effectiveness of Relieva Stratus™ MicroFlow spacer when added to BCD in the management of light and severe frontal chronic rhinosinusitis.

CONCLUSIONS

BCD is an acclared option in the management of frontal CRS and in the near future, utilization of stents/spacers could become a new and effective weapon in the management of rhinosinusitis, both like an adjunct to standard therapies, and in patient populations where the use of systemic drugs is contraindicated.

Use of balloon catheter dilation vs. traditional endoscopic sinus surgery in management of light and severe chronic rhinosinusitis of the frontal sinus: a multicenter prospective randomized study

OBJECTIVE

Chronic rhinosinusitis (CRS) of the frontal sinus is a complex pathological condition and many surgical techniques were described to treat this area endoscopically, like traditional endoscopic sinus surgery (ESS) and balloon catheter dilation (BCD).

PATIENTS AND METHODS

We designed a multicenter prospective randomized study to assess the validity and safety of BCD vs. ESS in symptomatological chronic rhinosinusitis of the frontal sinus enrolling a population of 102 adult patients (64 men and 38 women; overall 148 frontal sinuses studied) with non-polypoid CRS. For a better evaluation of the disease, in our study we decided to analyze both radiological (Lund-McKay CT scoring modified by Zinreich) and symptomatological results (SNOT-20 questionnaire). We divided the population affected in two groups, one with light/mild frontal CRS and the other with moderate/severe frontal CRS, basing on radiological findings at Lund-MacKay modified by Zinreich score. Every group was divided in two subgroups, in one we used BCD and in the other we used traditional ESS.

RESULTS

The current literature does not support the suggestion that indications for BCD and ESS are identical, and additional research is needed to determine the role for BCD in specific patient populations. The results showed a not statistically significative difference between BCD and conventional ESS of the frontal sinus in patients with light/mild CRS and in patients with moderate/severe CRS at Lund-Mackay modified by Zinreich score. The same not statistically significative difference was observed comparing the results of SNOT-20 questionnaire in the group of light/mild frontal chronic rhinosinusitis. However, we noticed a statistically significant better outcome of SNOT-20 score in patients with moderate/severe chronic rhinosinusitis that underwent BCD of frontal sinus compared to ESS.

CONCLUSIONS

BCD and ESS are two alternative weapons in the baggage of every endoscopic surgeon, even because they present similar outcomes, safeness and effectiveness both in light/mild and moderate/severe chronic rhinosinusitis of the frontal sinus. An interesting result of our study was the statistically significant better outcome of SNOT-20 score in patients that underwent BCD of frontal sinus for a moderate/severe CRS, compared to those that underwent a traditional ESS.

So close, so different: geothermal flux shapes divergent soil microbial communities at neighbouring sites

This study is focused on the (micro)biogeochemical features of two close geothermal sites (FAV1 and FAV2), both selected at the main exhalative area of Pantelleria Island, Italy. A previous biogeochemical survey revealed high CH4 consumption and the presence of a diverse community of methanotrophs at FAV2 site, whereas the close site FAV1 was apparently devoid of methanotrophs and recorded no CH4 consumption. Next-Generation Sequencing (NGS) techniques were applied to describe the bacterial and archaeal communities which have been linked to the physicochemical conditions and the geothermal sources of energy available at the two sites. Both sites are dominated by Bacteria and host a negligible component of ammonia-oxidizing Archaea (phylum Thaumarchaeota). The FAV2 bacterial community is characterized by an extraordinary diversity of methanotrophs, with 40% of the sequences assigned to Methylocaldum, Methylobacter (Gammaproteobacteria) and Bejerickia (Alphaproteobacteria); conversely, a community of thermo-acidophilic chemolithotrophs (Acidithiobacillus, Nitrosococcus) or putative chemolithotrophs (Ktedonobacter) dominates the FAV1 community, in the absence of methanotrophs. Since physical andchemical factors of FAV1, such as temperature and pH, cannot be considered limiting for methanotrophy, it is hypothesized that the main limiting factor for methanotrophs could be high NH4(+) concentration. At the same time, abundant availability of NH4(+) and other high energy electron donors and acceptors determined by the hydrothermal flux in this site create more energetically favourable conditions for chemolithotrophs that outcompete methanotrophs in non-nitrogen-limited soils.

Lab-scale tests and numerical simulations for in situ treatment of polluted groundwater

Methyl tert-butyl ether (MTBE) is used at significant percentages as an additive of unleaded gasoline. The physical-chemical properties of the substance (water solubility, soil organic carbon-water partition coefficient) cause high mobility and high concentrations in groundwater. Laboratory scale batch and column tests and mathematical modeling were performed to study the feasibility of a biobarrier (BB), that is an in situ permeable biological barrier with or without inoculation, for the remediation of MTBE and other gasoline-derived pollutants (benzene, toluene, ethylbenzene, o-xylene and m+p-xylenes, BTEXs) polluted groundwater and to estimate kinetic constants. The experimental results showed simultaneous biodegradation of MTBE and BTEXs, with similar removals in the uninoculated and the inoculated systems. Ranges for the first order kinetic removal were obtained for MTBE ((0.18±0.02)/(0.28±0.11d(-1))), B ((0.39±0.12)/(0.56±0.12d(-1))), T ((0.51±0.03)/(0.78±0.15d(-1))), E ((0.46±0.18)/(1.57±0.21d(-1))), o-X ((0.24±0.08)/(0.64±0.09d(-1))) and m+p-X ((0.20±0.04)/(1.21±0.04d(-1))). The results of the laboratory tests allowed to improve mathematical modeling in order to design a full-scale BB at a gasoline-contaminated site.

Season linked responses to fine and quasi-ultrafine Milan PM in cultured cells

Exposure to urbane airborne particulate matter (PM) is related to the onset and exacerbation of cardiovascular and respiratory diseases. The fine (PM1), and quasi-ultrafine (PM0.4) Milan particles collected during different seasons have been characterised and the biological effects on human epithelial lung A549, monocytes THP-1 cells and their co-culture, evaluated and compared with the results obtained on the PM10 and PM2.5 fractions. Chemical composition and transmission electron microscopy (TEM) analysis of PM0.4 showed that this fraction was very similar to PM1 for biological responses and dimension. All the winter fractions increased within 1h the level of reactive oxygen species (ROS), while only summer PM2.5 had this effect on A549 cells. The phosphorylation of H2AX (γH2AX), a marker of double strand DNA breaks (DSBs), was increased by all the winter fractions on A549 and THP-1 cells while summer PM samples did not induced this effect. PM0.4 and PM1 biological effects are partly similar and related to the season of sampling, with effects on ROS and DNA damage induced only by winter PM fractions. The winter PM damaging effect on DNA correlates with the presence of organic compounds.

Antibiotic resistance in bacteria associated with coarse atmospheric particulate matter in an urban area

AIMS

To assess antibiotic resistance in airborne bacteria associated with coarse particulate matter (PM10) in an urban area, with specific considerations about the Staphylococcus genus.

METHODS AND RESULTS

Disc diffusion test was performed on 243 microbial strains, isolated from PM10 in winter and summer and belonging to families Pseudomonadaceae and Enterobacteriaceae and genera Acinetobacter, Enterococcus and Staphylococcus. Staphylococci resistances were the most heterogeneous, being distributed among almost all tested antibiotics. Staphylococcus isolates resistant to some selected antibiotics were further investigated for the presence of the corresponding genetic determinants. Only tetK, which mediates the tetracycline resistance through the action of an efflux protein, was found in almost all resistant isolates.

CONCLUSIONS

The lack of specific genetic determinants makes their transmission among staphylococci less likely. This may reduce the theoretical risk associated with the inhalation of airborne micro-organisms.

SIGNIFICANCE AND IMPACT OF STUDY

Although the spreading of antibiotic resistant micro-organisms is of particular concern in clinical settings, the origin of antibiotic resistance genes can be traced in natural environments. As behaviour, viability and transport of bacteria in the atmospheric compartment suffer from a lack of information, the evaluation of the actual risk posed by airborne micro-organisms to human health is still challenging.

Slurry phase bioremediation of PAHs in industrial landfill samples at laboratory scale

The effect of Tween 80 and selected bacteria additions on the bioremediation of PAH contaminated landfill soil (70.38mgkg(-1)) was evaluated in a slurry phase bioreactor. A phenanthrene-degrading consortium was selected by enrichment cultures and used as autochthonous inoculum. The Tween 80 addition increased the aqueous concentration of both high and low molecular weight PAHs. In the experiment with Tween 80 and inoculum addition, added microorganisms improved (>90%) the biodegradation of two- and three-ring PAHs as well as of the four-ring PAHs pyrene and fluoranthene. Biodegradation of the higher molecular weight PAHs was about 30% in experiments with Tween 80 addition, with and without inoculum addition.

Naphthalene biodegradation kinetics in an aerobic slurry-phase bioreactor

The research was focused on the slurry-phase biodegradation of naphthalene in soil. Among ex situ techniques, the slurry phase offers the advantage of increased availability of contaminants to bacteria. From naphthalene contaminated soil, a Pseudomonas putida M8 strain capable to degrade naphthalene was selected. Experiments were performed in a stirred and oxygenated reactor. In this study, the influence of air flow rate and agitation rate on volatilisation and biodegradation of naphthalene was investigated. The hydrocarbon disappearance, the carbon dioxide production, and the ratio of total heterotrophic and naphthalene-degrading bacteria was monitored. The results obtained confirm that the selected bioremediation technology is successful in the treatment of contaminated soils.

Bioremediation of diethylhexyl phthalate contaminated soil: a feasibility study in slurry- and solid-phase reactors

The aim of the research was to verify the possibility of applying bioremediation as a treatment strategy on a poly(vinyl chloride) (PVC) manufacturing site in the north of Italy contaminated by diethylhexyl phthalate (DEHP) at a concentration of 5.51 mg/g of dry soil. Biodegradation kinetic experiments with DEHP contaminated soil samples were performed in both slurry- and solid-phase systems. The slurry-phase results showed that the cultural conditions, such as N and P concentrations and the addition of a selected DEHP degrading strain, increased the natural DEHP degradation rate. On the basis of these data, experiments to simulate bioventing on contaminated soil columns were performed. The DEHP concentration reached 0.63 mg/g of dry soil in 76 days (89% of degradation). A kinetic equation was developed to fit the experimental data and to predict the concentration of contaminant after treatment. The data obtained are encouraging for a future in situ application of the bioventing technology.