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With the advent of DNA-based molecular technologies, microbial ecologists now have the tools to test whether general ecological patterns apply to microorganisms. In this study, we selected ii high-mountain lakes from Sierra Nevada (Spain) to test the predictions of island-biogeography theory in relation to ecosystem size and isolation, and to assess the influence of other factors (i.e., ecosystem productivity, resource richness, and biotic interactions) on bacterial community structure. Bacterial operational taxonomic units (OTUs), generated by denaturing-gradient gel electrophoresis of polymerase chain-reaction- amplified 16S rRNA genes, were used as a surrogate of predominant "biodiversity units." OTU composition among lakes was heterogeneous, and the number of site-specific OTUs was near 50%. Lake remoteness did not affect the number of bacterial OTUs although the spatial distribution of the lakes significantly influenced bacterial composition. Lakes that were closer together had more similar bacterial fingerprints. We found a consistent positive association between bacterial OTU richness and lake area. The slope of this relationship (0.161 ± 0.026, including literature data) was similar to slopes obtained for organisms with high dispersion rates. [ABSTRACT FROM AUTHOR]

Assesses the influence of environmental factors on dissolved organic carbon (DOC) concentration and color dynamics in a forested lake where water residence time was relatively short in Connecticut. Determination of photobleaching and photomineralization rates over the different seasons; Comparison between absorption coefficients at 440 nanometers (a440) half lives of water column & water residence; Importance of in-lake properties an processes in forecasting DOC & a440 dynamics and their functions in lakes.

Extreme hydrological and thermal regimes characterize the Mediterranean zone and can influence the phenology of greenhouse gas (GHG) emissions in reservoirs. Our study examined the seasonal changes in GHG emissions of a shallow, eutrophic, hardwater reservoir in Spain. We observed distinctive seasonal patterns for each gas. CH4 emissions substantially increased during stratification, influenced predominantly by the increase in water temperature, net ecosystem production, and the decline in reservoir mean depth. N2O emissions mirrored CH4's seasonal trend, significantly correlating to water temperature, wind speed, and gross primary production. Conversely, CO2 emissions decreased during stratification and displayed a quadratic, rather than a linear relationship with water temperature—an unexpected deviation from CH4 and N2O emission patterns—likely associated with photosynthetic uptake of bicarbonate and formation of intracellular calcite that might be exported to sediments. This investigation highlights the imperative of integrating these idiosyncratic patterns into GHG emissions models, enhancing their predictive power. [ABSTRACT FROM AUTHOR]

Abstract The long-range transport of bioaerosols takes place in the free troposphere and has lately gained a renewed interest in both environmental and health-related disciplines. Sampling free troposphere bioaerosols has been, however, historically challenging and requires of expensive and complex facilities. We analysed different bacterial bioaerosols studies carried out by sequencing of the 16S rRNA gene, available from the literature. The dataset was compared with bacterial bioaerosols present in rain and dry deposition passively collected at high-elevation sites in Sierra Nevada along a set of sampling periods lasting 3 years. Up to 65% of OTUs and 82% of the bacterial genera were shared between wet and dry bioaerosols. Interestingly, only Oxalobacteraceae were notably more abundant in wet deposition, with Noviherbaspirillum and Massilia as dominant genera. We demonstrated that the bacterial composition of bioaerosols collected by passive natural deposition at high-elevated mountains were closer to the bacterial microbiome from the free troposphere. Interestingly, the meta-analysis showed a different bacterial composition and community structure in bacterial bioaerosols collected at low-elevated areas, over the open ocean, or during desert dust events. Since the boundary layer can be easily reached in high mountain areas, and the local landscape is surrounded by rocks and meadows, alpine stations are potentially optimal research sites with reduced influence of surface aerosols, minimizing local contaminations. Consequently, sampling alpine bioaerosols could be a good proxy for bioaerosols monitoring, long-range dispersal studies, and the dynamic characterization of the free troposphere microbiome. Highlights • Different bacterial bioaerosols exist at high-elevation mountains, low lands, over the open ocean, or during desert dust events. • Bacterial bioaerosols ground-sampled above the boundary layer were largely convergent with the free troposphere microbiome. • Airborne sampling stations at high-elevation mountains are a good proxy for long-term monitoring of the globally transported microbiome. [ABSTRACT FROM AUTHOR]

• We measured TEP from surface to deep waters across the Mediterranean Sea. • The proportion of TEP in the POC pool varies between ocean basins and depth layers. • Heterotrophic prokaryotes are a significant net source of TEP in the deep ocean. Transparent exopolymer particles (TEP) play a key role in ocean carbon export and structuring microbial habitats, but information on their distribution across different ocean basins and depths is scarce, particularly in the dark ocean. We measured TEP vertical distribution from the surface to bathypelagic waters in an east-to-west transect across the Mediterranean Sea (MedSea) and the adjacent North East Atlantic Ocean (NEA), and explored their physical and biological drivers. TEP ranged from 0.6 to 81.7 µg XG eq L−1, with the highest values in epipelagic waters above the deep chlorophyll maximum, and in areas near the Gibraltar and Sicily Straits. TEP were significantly related to particulate organic carbon (POC) in all basins and depth layers (epipelagic vs. deep), but the contribution of TEP to POC was higher in the NEA (85%, 79% and 67% in epi-, meso- and bathypelagic waters, respectively) than in the MedSea (from 53% to 62% in epipelagic waters, and from 45% to 48% in meso- and bathypelagic waters), coinciding with higher carbon to nitrogen particulate organic matter ratios in the NEA. The TEP connectivity between epipelagic waters and mesopelagic waters was less straightforward than between mesopelagic waters and bathypelagic waters, with a 23% and 55% of the variance in the relationship between layers explained respectively. Prokaryotes were found to be a likely net source of TEP as inferred by the significant direct relationship observed between prokaryotic heterotrophic abundance and TEP. This assumption was confirmed using experimental incubations, where prokaryotes produced TEP in concentrations ranging from 0.7 (Western Mediterranean, bathypelagic) to 232 (Western Mediterranean, mesopelagic) µg XG eq. L−1 day−1. [ABSTRACT FROM AUTHOR]

Due to the scarcity of organic matter (OM) sources in the bathypelagic (1000–4000 m depth), prokaryotic metabolism is believed to be concentrated on particles originating from the surface. However, the structure of active bathypelagic prokaryotic communities and how it changes across environmental gradients remains unexplored. Using a combination of 16S rRNA gene and transcripts sequencing, metagenomics, and substrate uptake potential measurements, here we aimed to explore how water masses aging and the quality of OM influence the structure of the active microbiome, and the potential implications for community function. We found that the relative contribution of taxa with a free‐living lifestyle to the active microbiome increased in older water masses that were enriched in recalcitrant OM, suggesting that these prokaryotes may also play a substantial role in the bathypelagic metabolism of vast areas of the ocean. In comparison to particle‐associated prokaryotes, free‐living prokaryotes exhibited lower potential metabolic rates, and harbored a limited number of two‐component sensory systems, suggesting they have less ability to sense and respond to environmental cues. In contrast, particle‐associated prokaryotes carried genes for particle colonization and carbohydrate utilization that were absent in prokaryotes with a free‐living lifestyle. Consistently, we observed that prokaryotic communities inhabiting older waters displayed reduced abilities to colonize particles, and higher capabilities to use complex carbon sources, compared to communities in waters with a higher proportion of labile OM. Our results provide evidence of regionalization of the bathypelagic active prokaryotic microbiome, unveiling a niche partitioning based on the quality of OM. [ABSTRACT FROM AUTHOR]

Water is the most indispensable natural resource; yet, organic pollution of freshwater sources is widespread. In recent years, there has been increasing concern over the vast array of emerging organic contaminants (EOCs) in the effluent of wastewater treatment plants (WWTPs). Several of these EOCs are degraded within the pore space of riverbeds by active microbial consortia. However, the mechanisms behind this ecosystem service are largely unknown. Here, we report how phosphate concentration and predator–prey interactions drive the capacity of bacteria to process a model EOC (ibuprofen). The presence of phosphate had a significant positive effect on the population growth rate of an ibuprofen-degrading strain. Thus, when phosphate was present, ibuprofen removal efficiency increased. Moreover, low and medium levels of predation, by a ciliated protozoan, stimulated bacterial population growth. This unimodal effect of predation was lost under high phosphate concentration, resulting in the flattening of the relationships between predator density and population growth of ibuprofen degraders. Our results suggest that moderate nutrient and predation levels promote the growth rate of bacterial degraders and, consequently, the self-purifying capability of the system. These findings enhance our understanding of the mechanisms by which riverbed communities drive the processing of EOCs. [ABSTRACT FROM AUTHOR]

We quantified dry and wet deposition of dust, nitrogen, and phosphorus over the southwest Mediterranean region (Sierra Nevada, Spain) and assessed its effects on the nutrient status and the chlorophyll a (Chl a) concentration in two high mountain lakes. Atmospheric deposition of particulate matter (PM) and total phosphorus (TP) were mainly associated with dryfall and showed a seasonal pattern similar to that reported for Saharan dust export toward the Mediterranean region, with maxima during spring and summer. In contrast, total nitrogen (TN) deposition was related to rainfall and did not follow the pattern observed for PM and TP. The molar TN:TP ratio was significantly lower (i.e., phosphorus-enriched) in dry deposition (TN vs. TP slope = 11.2) than in wet deposition (TN vs. TP slope = 95.5). In the study lakes, the molar TN:TP ratios and the Chl a concentrations were significantly influenced by the molar TN:TP ratio and the TP content of atmospheric deposition, respectively. Lake responses were more pronounced in the more phosphorous-limited system. These results establish a direct connection between atmospheric deposition and lake nutrient status and Chl a, making evident that in the Mediterranean region these inputs are an important source of phosphorous affecting biogeochemistry of oligotrophic systems. [ABSTRACT FROM AUTHOR]

Coastal wetlands are valuable aquatic ecosystems with high biological productivity, which provide services such as a reduction in nitrogen loading into coastal waters and storage of organic carbon acting as carbon dioxide sinks. The predicted rise of sea level or freshwater extractions, particularly in the arid Mediterranean biome, will salinize many coastal wetlands. However, there is considerable uncertainty about how salinization will affect microbial communities and biogeochemical processes. We determined the abundance of total prokaryotes, cyanobacteria, and viruses and quantified the heterotrophic production of prokaryotes sensitive- (predominantly Bacteria) and resistant- (predominantly Archaea) to erythromycin in 112 ponds from nine coastal wetlands. We explored the main drivers of prokaryotic abundance and heterotrophic production using generalized linear models (GLMs). The best GLM, including all the wetlands, indicated that the concentration of total dissolved nitrogen (TDN) positively affected the total abundance of prokaryotes and the heterotrophic erythromycin-resistant (ery-R) production. In contrast, heterotrophic erythromycin-sensitive (ery-S) production was negatively related to TDN. This negative relationship appeared to be mediated by salinity and virus abundance. Heterotrophic ery-S production declined as salinity and virus abundance increased. Consequently, we observed a switch from heterotrophic ery-S production towards ery-R production as salinity and virus abundance increased. Our results imply that microbial activity will change from heterotrophic bacterial-dominated processes to archaeal-dominated processes with anthropogenic nitrogen and salinization increases. However, more studies are required to link the mineralization rates of dissolved nitrogen and organic carbon with specific archaeal taxa to enable more accurate predictions on future scenarios in coastal wetlands. [ABSTRACT FROM AUTHOR]

Highlights • Peaks A, C and M distributions in epipelagic waters are mainly explained by AOU and temperature. • Peaks E and T distributions in epipelagic waters are mainly explained by PHA. • Water mass mixing explains FDOM distribution in meso– and bathypelagic waters. Abstract Fluorescent dissolved organic matter (FDOM) in the Mediterranean Sea was analysed by excitation–emission matrix (EEM) spectroscopy and parallel factor (PARAFAC) analysis during the cruise HOTMIX 2014. A 4–component model, including 3 humic–like and 1 protein–like compounds, was obtained. To decipher the environmental factors that dictate the distributions of these components, we run generalized additive models (GAMs) in the epipelagic layer and an optimum multiparametric (OMP) water masses analysis in the meso– and bathypelagic layers. In the epipelagic layer, apparent oxygen utilization (AOU) and temperature presented the most significant effects on the variability of the marine humic-like peak M fluorescence, suggesting that its distribution was controlled by the net community respiration of organic matter and photobleaching. On the contrary, the variability of the soil humic-like peak E and the protein–like peak T fluorescence was explained mainly by the prokaryotic heterotrophic abundance, which decreased eastwards. In the meso– and bathypelagic layers, water mass mixing and basin–scale mineralization processes explained >72% and 63% of the humic–like and protein–like fluorescence variability, respectively. When analysing the two basins separately, the OMP model offered a better explanation of the distribution of fluorescence in the eastern Mediterranean Sea, as expected from the reduced biological activity in this ultra–oligotrophic basin. Furthermore, while western Mediterranean deep waters display the usual trend in the global ocean (increase of humic–like fluorescence and decrease of protein–like fluorescence with higher AOU values), the eastern Mediterranean deep waters presented an opposite trend. Different initial fluorescence intensities of the water masses that mix in the eastern basin, with Adriatic and Aegean origins, seem to be behind this contrasting pattern. The analysis of the transect–scale mineralization processes corroborate this hypothesis, suggesting a production of humic–like and a consumption of protein–like fluorescence in parallel with water mass ageing. Remarkably, the transect–scale variability of the chromophoric dissolved organic matter (CDOM) absorbing at the excitation wavelength of the humic–like peak M indicates an unexpected loss with increasing AOU, which suggests that the consumption of the non–fluorescent fraction of CDOM absorbing at that wavelength exceeded the production of the fluorescent fraction observed here. [ABSTRACT FROM AUTHOR]

Chromophoric dissolved organic matter (CDOM) in the open Mediterranean Sea (MedSea) is barely documented, remaining the basin–wide patterns in intermediate and deep waters still enigmatic. Here, full–depth distributions of CDOM absorption coefficients and spectral slopes recorded during the HOTMIX 2014 cruise are presented and their respective environmental drivers resolved. General Additive Models (GAMs) in surface waters and Optimum MultiParameter (OMP) water mass analysis in deep waters were applied. In the surface, apparent oxygen utilisation (AOU), a proxy to cumulative net community respiration, explained most of the variability of dissolved organic carbon (DOC) and the absorption coefficient at 254 nm ( a 254 ), whereas the absorption coefficient at 325 nm ( a 325 ), and the spectral slopes were mostly explained by potential temperature, a proxy to stratification and solar radiation, indicating that both water column stability and photobleaching may drive the variability of the UV–A absorbing CDOM components. In deep waters, the effect of water mass mixing and basin–scale mineralization were discerned from local mineralization processes. Water mass mixing and basin–scale mineralization contributed more substantially to explain the variability of DOC, a 254 and a 325 (82–91%) than the variability of the spectral slopes (35–64%). Local mineralization processes indicate that DOC and CDOM play a more relevant role in the carbon cycle in the Eastern (EastMed) than in the Western (WestMed) Mediterranean: whereas DOC contributed to 66 ± 10% of the oxygen demand in the EastMed, it represented only 24 ± 4% in the WestMed. Independently of basins and layers, a 254 revealed as an excellent proxy to the concentration of DOC in the MedSea. Also, the unexpected inverse relationship of a 325 with AOU indicates that the consumption of the UV–A absorbing CDOM fraction prevails over their production. [ABSTRACT FROM AUTHOR]

Furthermore, panels c and d in the figure 1 were inverted and consequently, the figure did not match with the text and the figure caption. B Correction to: Microbial Ecology b https://doi.org/10.1007/s00248-022-02109-2 Due to a typesetting mistake during coding in R, units in the x-axis of figure 1c and d were wrongly written with a negative exponent (i.e. 10 SP -1 sp , 10 SP -2 sp , 10 SP -3 sp ,10 SP -4 sp ), while the exponent should be positive (i.e. 10 SP 1 sp , 10 SP 2 sp , 10 SP 3 sp ,10 SP 4 sp ). [Extracted from the article]

Objective: To evaluate the efficacy and tolerance of azithromycin in the prevention of post-extraction alveolar osteitis (dry socket) in women according to their use of tobacco and oral contraceptives., Method and Materials: A clinical trial was conducted in 400 women who underwent tooth extraction, stratified into 4 risk groups according to their use of tobacco (yes/no) and oral contraceptives (yes/no). Each stratum (n = 100) was randomly divided into 2 groups: a study group that received azithromycin 500 mg once daily for 3 days after extraction and a control group that received physiologic saline 3 times daily from 24 hours after extraction for 7 days., Results: Azithromycin was significantly superior to conventional postextraction treatment with physiologic saline. There were no significant interactions with the use of either tobacco or oral contraceptives, and these variables had no confounding effects., Conclusion: Azithromycin is a safe and efficacious treatment for the prevention of dry socket in women.