Dinitrogen-Fixing Cyanobacteria in Microbial Mats of Two Shallow Coral Reef Ecosystems

Dinitrogen-fixing organisms in cyanobacterial mats were studied in two shallow coral reef ecosystems: La Reunion Island, southwestern Indian Ocean, Sesoko (Okinawa) Island, and northwestern Pacific Ocean. Rapidly expanding benthic miniblooms, frequently dominated by a single cyanobacterial taxon, were identified by microscopy and molecular tools. In addition, nitrogenase activity by these blooms was measured in situ. Dinitrogen fixation and its contribution to mat primary production were calculated using 15N2 and 13C methods. Dinitrogen-fixing cyanobacteria from mats in La Reunion and Sesoko showed few differences in taxonomic composition. Anabaena sp. among heterocystous and Hydrocoleum majus and Symploca hydnoides among nonheterocystous cyanobacteria occurred in microbial mats of both sites. Oscillatoria bonnemaisonii and Leptolyngbya spp. occurred only in La Reunion, whereas Hydrocoleum coccineum dominated in Sesoko. Other mats dominated by Hydrocoleum lyngbyaceum, Phormidium laysanense, and Trichocoleus tenerrimus occurred at lower frequencies. The 24-h nitrogenase activity, as measured by acetylene reduction, varied between 11 and 324 nmoles C2H2 reduced µg−1 Chl a. The highest values were achieved by heterocystous Anabaena sp. performed mostly during the day. Highest values for nonheterocystous cyanobacteria were achieved by H. coccineum mostly during the night. Daily nitrogen fixation varied from nine (Leptolyngbya) to 238 nmoles N2µg−1 Chl day−1 (H. coccineum). Primary production rates ranged from 1,321 (S. hydnoides) to 9,933 nmoles C µg−1 Chl day−1 (H. coccineum). Dinitrogen fixation satisfied between 5% and 21% of the nitrogen required for primary production.Ocean Development Sub-Committee of France–Japan S&T Cooperation; Mitsubishi cooperation; The Ministry of Education, Science, Sport, and Culture of Japan; Hanse Wissenschaftskolleg; Delmenhorst and Alexander-von-Humboldt Foundation; Bad Godesberg; Germany supported collaborative research on cyanobacterial diversit

Changes in microbial communities in coastal sediments along natural CO2gradients at a volcanic vent in Papua New Guinea

Natural CO2 venting systems can mimic conditions that resemble intermediate to high pCO2 levels as predicted for our future oceans. They represent ideal sites to investigate potential long-term effects of ocean acidification on marine life. To test whether microbes are affected by prolonged exposure to pCO2 levels, we examined the composition and diversity of microbial communities in oxic sandy sediments along a natural CO2 gradient. Increasing pCO2 was accompanied by higher bacterial richness and by a strong increase in rare members in both bacterial and archaeal communities. Microbial communities from sites with CO2 concentrations close to today's conditions had different structures than those of sites with elevated CO2 levels. We also observed increasing sequence abundance of several organic matter degrading types of Flavobacteriaceae and Rhodobacteraceae, which paralleled concurrent shifts in benthic cover and enhanced primary productivity. With increasing pCO2, sequences related to bacterial nitrifying organisms such as Nitrosococcus and Nitrospirales decreased, and sequences affiliated to the archaeal ammonia-oxidizing Thaumarchaeota Nitrosopumilus maritimus increased. Our study suggests that microbial community structure and diversity, and likely key ecosystem functions, may be altered in coastal sediments by long-term CO2 exposure to levels predicted for the end of the century

Забезпечення якості медичної допомоги в умовах запровадження в Україні обов'язкового медичного страхування (адміністративно-правові принципи та складові елементи)

Аналізуються адміністративно правові принципи та складові елементи забезпечення якості медичної допомоги в умовах запровадження в Україні обов’язкового медичного страхування. Особлива увага приділена питанням контролю якості медичної допомоги. Ключові слова: якість надання медичної допомоги, обов’язкове медичне страхування.Анализируются административно правовые принципы и составляющие части обеспечения качества медицинской помощи в условиях утверждения в Украине обязательного медицинского страхования. Особое внимание уделено вопросам контроля качества оказания медицинской помощи. Ключевые слова: качество медицинской помощи, обязательное медицинское страхование.Administrative and legal principles and component parts of providing medical care quality in conditions of introducing compulsory medical insurance in Ukraine are analyzed in the article. Special attention is paid to the control provision of medical care quality. Key words: medical care quality, compulsory medical insurance

Living on the edge: Biofilms developing in oscillating environmental conditions

For the first time, the densities and diversity of microorganisms developed on ocean gliders were investigated using flow cytometry and Illumina MiSeq sequencing of 16S and 18S rRNA genes. Ocean gliders are autonomous buoyancy-driven underwater vehicles, equipped with sensors continuously recording physical, chemical, and biological parameters. Microbial biofilms were investigated on unprotected parts of the glider and surfaces coated with base, biocidal and chitosan paints. Biofilms on the glider were exposed to periodical oscillations of salinity, oxygen, temperature, pressure, depth and light, due to periodic ascending and descending of the vehicle. Among the unprotected surfaces, the highest microbial abundance was observed on the bottom of the glider’s body, while the lowest density was recorded on the glider’s nose. Antifouling paints had the lowest densities of microorganisms. Multidimensional analysis showed that the microbial communities formed on unprotected parts of the glider were significantly different from those on biocidal paint and in seawater

Intracellular nitrate storage by diatoms can be an important nitrogen pool in freshwater and marine ecosystems

Identifying and quantifying nitrogen pools is essential for understanding the nitrogen cycle in aquatic ecosystems. The ubiquitous diatoms represent an overlooked nitrate pool as they can accumulate nitrate intracellularly and utilize it for nitrogen assimilation, dissipation of excess photosynthetic energy, and Dissimilatory Nitrate Reduction to Ammonium (DNRA). Here, we document the global co-occurrence of diatoms and intracellular nitrate in phototrophic microbial communities in freshwater (n = 69), coastal (n = 44), and open marine (n = 4) habitats. Diatom abundance and total intracellular nitrate contents in water columns, sediments, microbial mats, and epilithic biofilms were highly significantly correlated. In contrast, diatom community composition had only a marginal influence on total intracellular nitrate contents. Nitrate concentrations inside diatom cells exceeded ambient nitrate concentrations ∼100–4000-fold. The collective intracellular nitrate pool of the diatom community accounted for <1% of total nitrate in pelagic habitats and 65–95% in benthic habitats. Accordingly, nitrate-storing diatoms are emerging as significant contributors to benthic nitrogen cycling, in particular through Dissimilatory Nitrate Reduction to Ammonium activity under anoxic conditions

Effect of biostimulation using sewage sludge, soybean meal and wheat straw on oil degradation and bacterial community composition in a contaminated desert soil

Waste materials have a strong potential in the bioremediation of oil-contaminated sites, because of their richness in nutrients and their economical feasibility. We used sewage sludge, soybean meal and wheat straw to biostimulate oil degradation in a heavily contaminated desert soil. While oil degradation was assessed by following the produced CO2 and by using gas chromatography-mass spectrometry (GC-MS), shifts in bacterial community composition were monitored using illumina MiSeq. The addition of sewage sludge and wheat straw to the desert soil stimulated the respiration activities more than the addition of soybean meal. GC-MS analysis revealed that the addition of addition of sewage sludge and wheat straw resulted in 1.7 to 1.8 fold increase in the degraded C14 to C30 alkanes, compared to only 1.3 fold increase in the case of soybean meal addition. The degradation of ≥ 90% of the C14 to C30 alkanes were measured in the soils treated with sewage sludge and wheat straw. MiSeq sequencing revealed that the majority (76.5-86.4% of total sequences) of acquired sequences from the original soil belonged to Alphaproteobacteria, Gammaproteobacteria and Firmicutes. Multivariate analysis of operational taxonomic units (OTUs) placed the bacterial communities of the soils after the treatments in separate clusters (ANOSIM R=0.66, P=0.0001). The most remarkable shift in bacterial communities was in the wheat straw treatment, where 95-98% of the total sequences belonging to Bacilli. We conclude that sewage sludge and wheat straw are useful biostimulating agents for the cleanup of oil-contaminated desert soils

Bacterial and fungal communities in biological soil crusts from Oman

Biological soil crusts (biocrusts) occur within drylands throughout the world, covering ~12% of the global terrestrial soil surface. Their occurrence in the deserts of the Arabian Peninsula has rarely been reported and their spatial distribution, diversity, and microbial composition remained largely unexplored. We investigated biocrusts at six different locations in the coastal and central deserts of Oman. The biocrust types were characterized, and the bacterial and fungal community compositions of biocrusts and uncrusted soils were analysed by amplicon sequencing. For each sample two different libraries were prepared: one for the V3V4 hypervariable region of the 16S rRNA gene (bacteria), and the other for the internal transcribed spacer 1 (ITS1; fungi). Sequences were processed in R using dada2. The code for sequence processing as well as statistical analysis, final OTU and taxonomy tables were archived on PANGAEA alongside the environmental information

Desert stream phototrophic mats: a promising source for biofuel production

<p>Desert streams occur in abundance in the mountain regions of the Arabian Peninsula, where massive areas are covered by phototrophic microbial mats. In this study, 11 different phototrophic microbial mats were screened for their carbohydrate and lipid contents and their ability to produce methane, and mats with potential were further used for biofuel production. A maximum bioethanol yield of 0.76 ± 0.1 g/L was obtained by enzymatic saccharification of one mat, which was dominated by the alga <i>Spirogyra</i>, followed by fermentation of the produced sugars using the native <i>Clostridium</i> strain AK-1. A lipid content of 9–18 wt% was measured from the microbial mats. An increase of 4% and 9% was observed, when the mat with the highest lipid content was incubated under 3% salinity and nitrogen deprivation conditions, respectively. Anaerobic digestion of one selected cyanobacterial mat for biomethane production yielded a maximum of 95 mL CH₄/g VS (volatile solids) after 49 days. MiSeq analysis revealed that the microbial community of this mat was 99.5% dominated by archaea, mainly belonging to the genera <i>Methanoculleus</i> (56.7%), <i>Methanobacterium</i> (27%) and <i>Methanosarcina</i> (7.6%). Our results demonstrate the potential of using microbial mats from desert streams to produce bioethanol, biodiesel and biomethane.</p