Marine sponge-associated actinomycetes are considered as promising sources for the discovery of novel biologically active compounds. In the present study, a total of 64 actinomycetes were isolated ...from 12 different marine sponge species that had been collected offshore the islands of Milos and Crete, Greece, eastern Mediterranean. The isolates were affiliated to 23 genera representing 8 different suborders based on nearly full length 16S rRNA gene sequencing. Four putatively novel species belonging to genera Geodermatophilus, Microlunatus, Rhodococcus and Actinomycetospora were identified based on a 16S rRNA gene sequence similarity of < 98.5% to currently described strains. Eight actinomycete isolates showed bioactivities against Trypanosma brucei brucei TC221 with half maximal inhibitory concentration (IC50) values <20 μg/mL. Thirty four isolates from the Milos collection and 12 isolates from the Crete collection were subjected to metabolomic analysis using high resolution LC-MS and NMR for dereplication purposes. Two isolates belonging to the genera Streptomyces (SBT348) and Micromonospora (SBT687) were prioritized based on their distinct chemistry profiles as well as their anti-trypanosomal activities. These findings demonstrated the feasibility and efficacy of utilizing metabolomics tools to prioritize chemically unique strains from microorganism collections and further highlight sponges as rich source for novel and bioactive actinomycetes.
The atmosphere has been described as one of the last frontiers of biological exploration on Earth. The composition of microbial communities in the atmosphere is still not well-defined, and taxonomic ...studies of bacterial diversity in the outdoor air have just started to emerge, whereas our knowledge about the functional potential of air microbiota is scant. When in the air, microorganisms can be attached to ambient particles and/or incorporated into water droplets of clouds, fog, and precipitation (i.e., rain, snow, hail). Further, they can be deposited back to earth’s surfaces via dry and wet deposition processes and they can possibly induce an effect on the diversity and function of aquatic and terrestrial ecosystems or impose impacts to human health through microbial pathogens dispersion. In addition to their impact on ecosystem and public health, there are strong indications that air microbes are metabolically active and well adapted to the harsh atmospheric conditions. Furthermore they can affect atmospheric chemistry and physics, with important implications in meteorology and global climate. This review summarizes current knowledge about the ubiquitous presence of microbes in the atmosphere and discusses their ability to survive in the atmospheric environment. The purpose is to evaluate the atmospheric environment as a source of pathogenic or beneficial microbes and to assess the biotechnological opportunities that may offer.
Background: The distribution of microorganisms, and especially pathogens, over airborne particles of different sizes has been ignored to a large extent, but it could have significant implications ...regarding the dispersion of these microorganisms across the planet, thus affecting human health. Objectives: We examined the microbial quality of the aerosols over the eastern Mediterranean region during an African storm to determine the size distribution of microorganisms in the air. Methods: We used a five-stage cascade impactor for bioaerosol collection in a coastal city on the eastern Mediterranean Sea during a north African dust storm. Bacterial communities associated with aerosol particles of six different size ranges were characterized following molecular culture-independent methods, regardless of the cell culturability (analysis of 16S rRNA genes). Results: All 16S rDNA clone libraries were diverse, including sequences commonly found in soil and marine ecosystems. Spore-forming bacteria such as Firmicutes dominated large particle sizes (> 3.3 micrometers), whereas clones affiliated with Actinobacteria (found commonly in soil) and Bacteroidetes (widely distributed in the environment) gradually increased their abundance in aerosol particles of reduced size (< 3.3 micrometers). A large portion of the clones detected at respiratory particle sizes (< 3.3 micrometers) were phylogenetic neighbors to human pathogens that have been linked to several diseases. Conclusions: The presence of aerosolized bacteria in small size particles may have significant implications to human health via intercontinental transportation of pathogens.
Active hydrothermal vents of volcanic origin provide a remarkable manifestation of life on Earth under extreme conditions, which may have consequences for our understanding of habitability on other ...terrestrial bodies as well.
Here, we performed for the first time Illumina sequencing of bacterial and archaeal communities on sub-seafloor samples collected from the Santorini-Kolumbo volcanic field. A total of 19 (3-m long) gravity corers were collected and processed for microbial community analysis.
From a total of 6,46,671 produced V4 sequences for all samples, a total of 10,496 different Operational Taxonomic Units (OTUs) were identified that were assigned to 40 bacterial and 9 archaeal phyla and 14 candidate divisions. On average, the most abundant phyla in all samples were Chloroflexi (Chloroflexota) (24.62%), followed by Proteobacteria (Pseudomonadota) (11.29%), Firmicutes (Bacillota) (10.73%), Crenarchaeota (Thermoproteota) (8.55%), and Acidobacteria (Acidobacteriota) (8.07%). At the genus level, a total of 286 known genera and candidate genera were mostly dominated by members of
, and
.
In most of the stations, the Chao1 values at the deeper layers were comparable to the surface sediment samples denoting the high diversity in the subsurface of these ecosystems. Heatmap analysis based on the 100 most abundant OTUs, grouped the sampling stations according to their geographical location, placing together the two hottest stations (up to 99°C). This result indicates that this specific area within the active Kolumbo crater create a distinct niche, where microorganisms with adaptation strategies to withstand heat stresses can thrive, such as the endospore-forming Firmicutes.
•We examined the pollution status of deep-sea sediments in the southern Cretan margin.•AHs, UCM, PAHs, PCBs and chlorinated pesticides were ubiquitous in sediments.•AHs and PAHs were of ...terrestrial-biogenic and pyrolytic origin, respectively.•The presence of PCBs and HCHs was attributed to historical emission sources.•An on-going, fresh input of DDT was revealed.
Deep sediments from the southern Cretan margin were analyzed to establish baseline levels for various types of organic pollutants before the anticipated intensification of anthropogenic activities. The total concentration of aliphatic hydrocarbons (ΣAH:326–3758ngg−1, dry weight) was similar to those reported for deep sediments of the western Mediterranean Sea, while considerably lower levels were measured for polycyclic aromatic hydrocarbons (ΣPAH:9–60ngg−1). Source-diagnostic ratios suggested that the aliphatic hydrocarbons in sediments were mainly of terrestrial biogenic origin, while polycyclic aromatic hydrocarbons stemmed from the deposition of long-range transported combustion aerosols. Among the organochlorinated compounds analyzed, β-hexachlorocyclohexane (β-HCH:222–7052pgg−1), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p′-DDT:37–2236pgg−1) and polychlorinated biphenyls (ΣPCB:38–1182pgg−1) showed the highest abundance in sediments. The presence of HCHs and PCBs was attributed to historical inputs that have undergone extensive weathering, whereas an ongoing fresh input was suggested for p,p′-DDT. Multiple linear regression analysis revealed that the levels of the various pollutants in sediments were controlled by different factors, but with organic carbon content playing a prominent role in most cases.
Although the rise of antibiotic and multidrug resistant bacteria is one of the biggest current threats to human health, our understanding of the mechanisms involved in antibiotic resistance selection ...remains scarce. We performed whole genome sequencing of 21 Pseudomonas strains, previously isolated from an active submarine volcano of Greece, the Kolumbo volcano. Our goal was to identify the genetic basis of the enhanced co-tolerance to antibiotics and acidity of these Pseudomonas strains. Pangenome analysis identified 10,908 Gene Clusters (GCs). It revealed that the numbers of phage-related GCs and sigma factors, which both provide the mechanisms of adaptation to environmental stressors, were much higher in the high tolerant Pseudomonas strains compared to the rest ones. All identified GCs of these strains were associated with antimicrobial and multidrug resistance. The present study provides strong evidence that the CO
-rich seawater of the volcano associated with low pH might be a reservoir of microorganisms carrying multidrug efflux-mediated systems and pumps. We, therefore, suggest further studies of other extreme environments (or ecosystems) and their associated physicochemical parameters (or factors) in the rise of antibiotic resistance.
Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle ...characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report (3)He/(4)He measurements in CO2-dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a (3)He/(4)He signature of at least 7.0 Ra (being Ra the (3)He/(4)He ratio of atmospheric He equal to 1.39×10(-6)), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like (3)He/(4)He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano.
Geochemistry of Kolumbo Gases (Greece) and worldwide aerial volcanic emissions. This finding may represent further evidence for the high level of magmatic activity at Kolumbo. Based on the ...geo-indicators of temperature and pressure, we calculate that the magmatic gases equilibrate within the Kolumbo hydrothermal system at about 270 • C and at a depth of ∼1 km b.s.l.
We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater ...of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe(3+)-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe(2+)-oxidation, dependent on microbially produced nitrate.
Over the last decades, there has been growing interest about the ecological role of hydrothermal sulfide chimneys, their microbial diversity and associated biotechnological potential. Here, we ...performed dual-index Illumina sequencing of bacterial and archaeal communities on active and inactive sulfide chimneys collected from the Kolumbo hydrothermal field, situated on a geodynamic convergent setting. A total of 15,701 OTUs (operational taxonomic units) were assigned to 56 bacterial and 3 archaeal phyla, 133 bacterial and 16 archaeal classes. Active chimney communities were dominated by OTUs related to thermophilic members of Epsilonproteobacteria, Aquificae and Deltaproteobacteria. Inactive chimney communities were dominated by an OTU closely related to the archaeon
Nitrosopumilus
sp., and by members of Gammaproteobacteria, Deltaproteobacteria, Planctomycetes and Bacteroidetes. These lineages are closely related to phylotypes typically involved in iron, sulfur, nitrogen, hydrogen and methane cycling. Overall, the inactive sulfide chimneys presented highly diverse and uniform microbial communities, in contrast to the active chimney communities, which were dominated by chemolithoautotrophic and thermophilic lineages. This study represents one of the most comprehensive investigations of microbial diversity in submarine chimneys and elucidates how the dissipation of hydrothermal activity affects the structure of microbial consortia in these extreme ecological niches.
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