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Water affects the susceptibility of stone to alteration by facilitating physical, chemical and biological weathering. Stone properties determine water transport and retention, but it is also expected that biofilms and extracellular polymeric substances could alter the water-stone relationship. A lot of research on this subject has been carried out on soils, but the effect on stones is understudied. For this reason, three sedimentary building stones, Ernzen, Euville and Savonnieres, each with a different pore size distribution, were biofouled with cyanobacteria. Their relationship with the stone material was investigated by optical and electron microscopy, and the effect of cyanobacterial biofilms on water transport and retention was studied. The results showed that the cyanobacteria primarily colonize the building stones on the outer surface and have a limited effect on the water transport properties. They slightly reduced the capillary coefficient and drying rate of the stones, but enhanced the water content in the stone and increased water vapour sorption. They induced (near) hydrophobic conditions, but had no measurable effect on the gas permeability and water vapour diffusion. Moreover, swelling and shrinkage of the biofilms were observed, which could potentially induce physical weathering. It is expected that these changes could influence other forms of weathering, such as freeze-thaw weathering and salt weathering.

Self-healing is a spontaneously occurring process during crack formation where CO2 and H2O are allowed in, leading to the formation of new carbonation and hydration products that can seal the crack. This well characterized phenomenon has proven useful as an effective method of extending the durability and service life of structures. Currently, multiple methods exist to assess the effectiveness of self-healing, yet coupled experiments that demonstrate quantitative and qualitative effects of the healing processes are scarce. In this work, a new technique is presented that couples water flow tests for recovery of durability, visual scans used to analyze surface healing and μCT for internal observation of crack morphology and dynamics. CEM II/A-LL 32.5R mortar was cast in cylinders of 45 mm diameter with a cast-in-hole and cracked at 7 days. Samples were placed in wet/dry cycles and water flow tests and superficial crack closure was assessed at 0 days, 28 days and 112 days after cracking. Finally, samples were scanned using μCT to demonstrate the potential of this novel protocol. The results highlight the importance of coupled tests to provide a more comprehensive evaluation of the healing process in mortars.

N,N-Dimethylformamide (DMF) is an organic solvent produced in large quantities worldwide. It is considered as a hazardous air pollutant and its emission should be controlled. However, only a limited number of studies have been performed on the removal of gaseous DMF by biological technologies. In this paper, we evaluate the removal of DMF under mesophilic and thermophilic conditions in a lab-scale biofilter for 472 days. The results show that, at ambient temperature, the biofilter achieved an average removal efficiency (RE) of 99.7 ± 0.3 % at Inlet Loads (ILs) up to 297 ± 52 g DFM m−3 h−1 (Empty Bed Residence Time (EBRTs) of 10.7 s). However, a decrease in EBRT (6.4 s) led to an unstable outlet concentration and, thus, to a drop in the biofilter performance (average RE: 90 ± 9 %). Moreover, an increase in temperature up to 65 °C led to a gradual decrease in RE (till 91 ± 7 %). Microbial analysis indicates that once the microorganisms encountered DMF, Rhizobiaceae dominated followed by Alcaligenaceae. Afterwards, a strong decrease in Rhizobiaceae was observed at every increase in temperature, and at 65 °C, the taxa were more heterogeneous. Overall, our experimental results indicate that biofiltration is a promising technique to remove DMF from waste gas streams.

Natural stones are essential for our built heritage. They are considered durable and permanent. However, they deteriorate through physical, chemical and biological action with water as the principal facilitator. Within a stone, water transport and retention depend on the stone's characteristics. It is expected that biofilms and extracellular polymeric substances change these properties and thus the water-stone relationship. To study the effect of the biofilms, three porous natural building stones: Ernzen, Euville and Savonnières, were biofouled with cyanobacteria Phormidium autumnale. The amount of biofilm was estimated by spectrophotometry, characterized by optical microscopy, and (environmental) scanning electron microscopy. Water transport and retention for biofouled and untreated samples were determined following European standards. Microscopy showed that the biofilms primarily covered the stone's outer surface. They experienced swelling and shrinkage dependent on the subjected relative humidity conditions, which could facilitate physical weathering. The biofilms slightly affected the water transport properties and induced a (near) hydrophobic surface. They reduced the drying rate and capillary coefficient. Moreover, biofouled samples absorbed more water vapor, had a higher water content, while no direct effect was measured on the water vapor diffusion and gas permeability. These changes could affect future weathering processes, including freeze-thaw and salt weathering.

Microbial communities are responsible for biological wastewater treatment, but our knowledge of their diversity and function is still poor. Here, we sequence more than 5 million high-quality, full-length 16S rRNA gene sequences from 740 wastewater treatment plants (WWTPs) across the world and use the sequences to construct the ‘MiDAS 4’ database. MiDAS 4 is an amplicon sequence variant resolved, full-length 16S rRNA gene reference database with a comprehensive taxonomy from domain to species level for all sequences. We use an independent dataset (269 WWTPs) to show that MiDAS 4, compared to commonly used universal reference databases, provides a better coverage for WWTP bacteria and an improved rate of genus and species level classification. Taking advantage of MiDAS 4, we carry out an amplicon-based, global-scale microbial community profiling of activated sludge plants using two common sets of primers targeting regions of the 16S rRNA gene, revealing how environmental conditions and biogeography shape the activated sludge microbiota. We also identify core and conditionally rare or abundant taxa, encompassing 966 genera and 1530 species that represent approximately 80% and 50% of the accumulated read abundance, respectively. Finally, we show that for well-studied functional guilds, such as nitrifiers or polyphosphate-accumulating organisms, the same genera are prevalent worldwide, with only a few abundant species in each genus., Nature Communications, 13, ISSN:2041-1723

Microorganisms, including bacteria, archaea, algae and fungi, colonize natural building stones. Bacteria are among the most relevant colonizers, as they impact substrates in multiple forms, primarily attributed to their high diversity. They alter rock properties, induce discoloration, dissolution or precipitation, which can lead to degradation over time or in some cases, protection. Numerous studies suggested a link between rock alteration and bacteria, although there are still inconclusive conclusions. Moreover, the role of archaea remains unresolved. Classical cultivation techniques capture a fraction of bacterial and archaeal diversity. Recently, culture-independent and omics-technologies provide tools to further understand their full diversity and true role. Based on field and experimental work, this comprehensive review provides an overview of biocolonization and potential changes during the 21st Century. To better understand the role of bacteria and archaea, the focus will be on their capabilities to alter natural building stones. It also includes a short overview of methods to understand the processes and dynamics of biocolonization. The conclusions of this work will not only improve our understanding of deterioration in general, but it can also make sustainable biorestoration with bacteria the preferred choice instead of chemical and physical agents.

N,N-Dimethylformamide (DMF) is an organic solvent produced in large quantities worldwide. It is considered as a hazardous air pollutant and its emission should be controlled. However, only a very limited number of studies have been performed on the removal of gaseous DMF by biological technologies. In this paper, we evaluate the removal of DMF under mesophilic and thermophilic conditions in a lab-scale biofilter packed with wood chips and compost. The performance of the biofilter was studied under varying inlet conditions using Selected Ion Flow Tube Mass Spectrometry (SIFT-MS). Furthermore, microbial analysis data is presented to identify the microorganisms responsible for DMF removal and observe their evolution over time. The results show that, at ambient temperature, the biofilter achieved removal efficiencies (RE) above 98% at Inlet Loads (ILs) up to 297±52 g DFM m-3 h-1 (EBRTs > 10.7 s). However, a decrease in Empty Bed Residence Time (EBRT) (6.4 s) associated with an increase in IL (380±129 g DFM m-3 h-1) led to an unstable outlet stream and, thus, to a drop in the biofilter performance. Moreover, an increase in temperature - from 21 to 65 °C - led to a decrease in RE. Overall, our experimental results indicate that biofiltration is a promising technique to remove DMF from waste gas streams, but a mechanistic understanding is needed to exploit its potential and rapid implementation in full-scale installations.

Supplementary Materials and Methods, Tables and Figures for Predicting the presence and abundance of bacterial taxa in environmental communities through flow cytometric fingerprinting.

Commonwealth war cemeteries commemorate the fallen of both world wars. Every casualty is remembered with a memorial or on a headstone. However, the headstones need to be maintained extensively, as microorganisms easily colonise them, affecting legibility and the stone substrate in the longer term. In the past, pesticides and other chemicals were popular to clean headstones, but due to raised environmental concerns, new treatment strategies are necessary. Within conservation science, enzymes have emerged as a popular tool for restoration. However, studies related to the use of enzymes for stone conservation are limited. Within this preliminary study, we applied commercially available enzyme-based treatments on biofouled natural building stones in the laboratory and in situ. Photography and spectrophotometry were used to monitor the effect of the treatment. The application of enzymes resulted in rapid disintegration of biological pigments, whereas visual improvement occurred more gradually. The successful application of enzymes suggests their potential to replace pesticides as the principal cleaning agent for headstones and natural building stones in a more general fashion.

Air pollution is one of the main actors of stone deterioration. It influences not only the material itself but also prokaryotes colonizing rocks. Prokaryotes can affect rock substrates and biological colonization will most likely become relatively more important during the course of the 21st century. Therefore, it is necessary to understand the effects of air pollution on biological colonization and on the impact of this colonization on rock weathering. For this reason, we studied the prokaryotic community of Lede stone from two deteriorated monuments in Belgium: one in the urban and one in the rural environment. This research conducts 16S rRNA gene Next Generation Sequencing combined with an isolation campaign. It revealed diverse and complex prokaryotic communities with more specialized bacteria present in the urban environment, while archaea were barely detected. Some genera could cause biodeterioration but the isolates did not produce a significant amount of acid. Soluble salts analysis revealed an important effect of salts on the prokaryotic community. Colour measurements at least indicate that a main effect of prokaryotes might be on the aesthetics: In the countryside prokaryotic communities seemed to discolour Lede stone, while pollution most likely blackened building stones in the urban environment.

Krabok and coconut oil were assessed for their ability to affect rumen protozoa via a 3×3 Latin square design experiment with three rumen cannulated beef cows. The diets consisted of a concentrate supplemented with either 25.5 g/kg of tallow (control) or the same quantity of coconut oil or krabok oil. The animals were fed at 1.5% of their body weight per d for 28 d per period. The samples of rumen fluid were collected on day 23 and 27 of each period, 3, 6, 9 and 12h after morning feeding. Rumen protozoa numbers, as well as amylolytic, cellulolytic and proteolytic bacteria were counted microscopically. Fragments of the 18S rRNA gene were amplified in a nested PCR using general eukaryotic and ciliate protozoa-specific primers (Euk1a and 539r followed by 316f- Euk516r-GC). Diversity of the ciliate community was analyzed by Denaturing Gradient Gel Electrophoresis (DGGE) (7% acrylamide, 35-50% gradient; 38 V for 16h at 60 ºC) and gels were processed with BioNumeric software. Protozoa numbers decreased by 0.33 log units in the coconut (P0.10) different between treatments. The propionate proportion was only reduced by supplementation of coconut oil to the TMR. Neither oils affected amylolytic, cellulolytic or proteolytic bacteria counts. Cluster analysis of the DGGE profile showed two clusters of ciliate communities, one including all the T diet-fed animals. All except one DGGE profile of a cow fed the KO diet group into the second cluster. Coconut oil, and to a lesser extent krabok oil, has a marked effect on the numbers of rumen protozoa.

Additional file 1.

Variations in the gut microbiome have been associated with changes in health state such as Crohn’s disease. Most surveys characterize the microbiome through analysis of the 16S rRNA gene. An alternative technology that can be used is flow cytometry. In this report we analyzed a disease cohort that has been characterized by both technologies. Changes in microbial community structure are reflected in both types of data. We demonstrate that cytometric fingerprints can be used as a diagnostic tool in order to classify samples according to Crohn’s disease state. These results highlight the potential of flow cytometry to perform rapid diagnostics of microbiome-associated diseases.

BACKGROUND: Microbial community dynamics during the anaerobic digestion of vinasse has been little studied. However, having knowledge about it is essential for early detection of reactor operational difficulties to apply preventive actions. This research studies the microbial community dynamics in the anaerobic digestion of vinasse, linking to experimental observations about product yields and organic matter degradation. RESULTS: Methane and sulfide yields decreased with increasing SO4 2-/COD ratio, while the fraction of organic matter degraded by sulfate reducing bacteria increased from 4.5 ± 0.3% to 27.1 ± 0.6%. The archaeal community showed that acetoclastic Methanosaetaceae were little affected by the increase of the SO4 2-/COD ratio, in contrast to the Methanomicrobiales and Methanobacteriales population, which decreased during the experiment. The total bacterial diversity was influenced mainly by substrate composition, showing that the increase of the SO4 2-/COD ratio above 0.10 shifted the bacterial community to a lower richness. CONCLUSION: These results provide knowledge on the dynamics of the microbial communities, which can be useful to control the anaerobic digestion of sulfate-rich vinasses, showing that reactor stability equates to the higher ratios between total methanogens and total bacteria gene copy numbers, whereas operational difficulties can be associated to lower bacterial richness and higher community organization.

Table S1. DNA yield obtained from the bead-beating cetyl trimethylammonium bromide (CTAB) phenol extraction [41] and the FastPrep [42] method from 1Â g of sample. (DOCX 19 kb)

Table S2. Diversity indexes for each of the sampled sites calculated for the complete and subsampled data. (DOCX 20 kb)

Table S1. DNA yield obtained from the bead-beating cetyl trimethylammonium bromide (CTAB) phenol extraction [41] and the FastPrep [42] method from 1Â g of sample. (DOCX 19 kb)

International audience; For most marine aquaculture species, one of the main bottlenecks is the stable production of high quality juveniles. The high and unpredictable mortality in the first weeks after hatching of marine fish larvae remains a challenging problem that needs to be solved. The severity of the problem differs between species, but cannot be considered adequately solved for any species. Both scientific evidence and experience in hatcheries for a variety of fish, shrimp and shellfish species are accumulating as support for the hypothesis that detrimental fish–microbe interactions are the cause of these problems. Host–microbe interactions in reared fish are still poorly understood, except for a few pathogens, and empirical data of the quality required to test this hypothesis, are lacking. This article provides an overview on the current knowledge of the microbial environment of fish larvae, including methodological aspects to characterize the microbial community (both using culture-dependent and culture-independent methods). Further, the current knowledge of the immunology of fish larvae is reviewed, including recent advances in the understanding of toll-like receptors, inflammatory cytokines, mast cells and piscidins, and the ontogeny of the adaptive immune system. Finally, we provide an overview of the state of the art with respect to steering of microbial communities associated with fish larvae – both steering of community composition and of its activity (e.g. by quorum sensing interference)

Obtaining a reliable estimation of the methane potential of organic waste streams in anaerobic digestion, for which a biochemical methane potential (BMP) test is often used, is of high importance. Standardization of this BMP test is required to ensure inter-laboratory repeatability and accuracy of the BMP results. Therefore, guidelines were set out; yet, these do not provide sufficient information concerning origin of and the microbial community in the test inoculum. Here, the specific contribution of the methanogenic community on the BMP test results was evaluated. The biomethane potential of four different substrates (molasses, bio-refinery waste, liquid manure and high-rate activated sludge) was determined by means of four different inocula from full-scale anaerobic digestion plants. A significant effect of the selected inoculum on the BMP result was observed for two out of four substrates. This inoculum effect could be attributed to the abundance of methanogens and a potential inhibiting effect in the inoculum itself, demonstrating the importance of inoculum selection for BMP testing. We recommend the application of granular sludge as an inoculum, because of its higher methanogenic abundance and activity, and protection from bulk solutions, compared with other inocula.

EUROBIOFILMS 2017 - 5th European Congress on Microbial Biofilms, An imbalance in the periodontal microbiota and dysbiosis deregulate the host immune response, leading to chronic inflammation. Since little is k nown about the initiation of dysbiosis, it can be hypothesized that some commensal bacteria can suppress the outgrowth of pathobionts by H 2 O 2 production. However, serum and blood components released during inflammation can neutralize this suppressive effec t, leading to the initiation of dysbiosis. The aim of this study is to determine if the neutralizing effect of serum, hemoglobin and hemin on the inhibitory effect of the commensal bacteria on pathobiont growth is translated in a more pronounced immune res ponse. Bacterial quantitative PCR, expression analysis of bacterial virulence and cellular inflammatory genes and cytokine quantification by ELISA were performed to quantify the pathobiont outgrowth and to detect possible differences in inflammatory respon se after exposure of cell cultures to homeostatic or dysbiotic biofilms. Peroxidases, serum and blood components neutralized the inhibitory effect of H 2 O 2 by exogenous peroxidase activity, increasing the pathobiont outgrowth. Moreover, the addition of seru m, peroxidase and blood compounds upregulated the main virulence genes of P. gingivalis and P. intermedia in multi - species biofilms. Exposure of epithelial and fibroblast cultures to these dysbiotic biofilms increased the expression of IL6, IL1β, TNFα and MMP8, but especially of IL8. Moreover, higher amounts of IL8 were produced after the challenge with dysbiotic biofilms. Conversely, homeostatic and commensal biofilms had a minor inflammatory response at expression and protein level. Overall, serum, peroxi dases or blood compounds allowed the outgrowth of pathobionts and increased their virulence. Dysbiotic biofilms enriched in pathobionts and virulence factors significantly increased the inflammatory response compared to homeostatic and commensal biofilms, info:eu-repo/semantics/publishedVersion

Rapid contamination of drinking water in distribution and storage systems can occur due to pressure drop, backflow, cross-connections, accidents, and bio-terrorism. Small volumes of a concentrated contaminant (e.g., wastewater) can contaminate large volumes of water in a very short time with potentially severe negative health impacts. The technical limitations of conventional, cultivation-based microbial detection methods neither allow for timely detection of such contaminations, nor for the real-time monitoring of subsequent emergency remediation measures (e.g., shock-chlorination). Here we applied a newly developed continuous, ultra high-frequency flow cytometry approach to track a rapid pollution event and subsequent disinfection of drinking water in an 80-min laboratory scale simulation. We quantified total (TCC) and intact (ICC) cell concentrations as well as flow cytometric fingerprints in parallel in real-time with two different staining methods. The ingress of wastewater was detectable almost immediately (i.e., after 0.6% volume change), significantly changing TCC, ICC, and the flow cytometric fingerprint. Shock chlorination was rapid and detected in real time, causing membrane damage in the vast majority of bacteria (i.e., drop of ICC from more than 380 cells μl-1 to less than 30 cells μl-1 within 4 min). Both of these effects as well as the final wash-in of fresh tap water followed calculated predictions well. Detailed and highly quantitative tracking of microbial dynamics at very short time scales and for different characteristics (e.g., concentration, membrane integrity) is feasible. This opens up multiple possibilities for targeted investigation of a myriad of bacterial short-term dynamics (e.g., disinfection, growth, detachment, operational changes) both in laboratory-scale research and full-scale system investigations in practice., Frontiers in Microbiology, 8, ISSN:1664-302X

Demand for construction materials has been rising in recent decades in many countries around the world, placing a heavy burden on the environment in terms of both the natural resources consumed and the enormous flow of waste generated. In order to obtain a more sustainable construction, it is often suggested to reintroduce the industry’s own waste as input for the manufacture of new materials. In this study, the use of construction and demolition waste of concrete or mixed concrete/ceramic nature is investigated as a replacement of natural aggregates in concrete. The greater affinity of recycled aggregates for water directly affects the workability and/or the concrete strength and durability. One possible solution to reduce the aggregates water absorption is to apply a biogenic treatment with calcium carbonate-precipitating bacteria that consolidate the aggregate surface or the adhering mortar. Experimental results show that the biodeposition treatment reduced the recycled aggregate water absorption by generating precipitation in the pores and an impermeable outer layer, most effectively on the roughest particle surfaces. The largest decrease happened in the aggregates with the highest porosity. The biogenic layer had a good cohesion with the aggregates. The results of sonication indicated that the most effective treatment was on recycled concrete aggregates (RCA) instead of mixed aggregates (MA). Therefore, the treated RCA was used to make concrete for further investigation. The concrete made with bio-treated RCA had a denser structure, a decreased water absorption (around 1%) and an improved compressive strength (25%).

Surface treatment is a frequently used method for conservation and restoration of building materials. . In this study, a novel and environment friendly strategy, bacterially induced calcium carbonate precipitation was applied to strengthen the surface of limestone. The treatment procedure for bio-deposition was first optimized regarding the aspects of treatment frequency and treatment time. Ultrasonic velocity was used to characterize the surface properties. It turned out that two subsequent applications of a one-step bio-deposition treatment had the best effect, where the transmitting velocity of the ultrasonic wave was increased with around 10~20%. The improvement mainly occurred from the surface till the depth of 4 cm and the largest increase was at the depth around 2 cm. Meanwhile, a commercial chemical ethyl silicate based consolidant, was applied under the same condition. Yet the efficiency measured by the increase in ultrasonic velocity was not significant.

Additional file 1. Supplementary information in form of supplementary figures, tables containing enriched species per conditions and extended information on molecular analysis methodology.

Single cells can be characterized in terms of their phenotypic properties using flow cytometry. However, up to our knowledge there has not yet been a thorough survey concerning the classification of bacterial species based on flow cytometric data. This paper aims to perform a thorough investigation concerning the identification of bacterial communities of various complexities in species richness. We do this by creating so-called in silico communities, communities created by aggregating the data coming from individual cultures; moreover we show that it is possible to use in silico communities to identify in vitro created communities as well, proving the biological relevance and usability of bacterial in silico communities.

Flow cytometry is able measure up to 50.000 cells in various dimensions in seconds of time. This large amount of data gives rise to the possibility of making predictions at the single-cell level, however, applied to bacterial populations a systemic investigation lacks. In order to combat this deficiency, we cultivated twenty individual bacterial populations and measured them through flow cytometry. By creating in silico communities we are able to use supervised machine learning techniques in order to examine to what extent single-cell predictions can be made; this can be used to identify the community composition. We show that for more than half of the communities consisting out of two bacterial populations we can identify single cells with an accuracy >90%. Furthermore we prove that in silico communities can be used to identify their in vitro counterpart communities. This result leads to the conclusion that in silico communities form a viable representation for synthetic bacterial communities, opening up new opportunities for the analysis of bacterial flow cytometric data and for the experimental study of low-complexity communities.

Microbial single cells can be characterized by their phenotypic properties using flow cytometry. Therefore flow cytometry can be used to analyze various aspects of environmental microbial communities. In recent years, researchers have focused on fully exploiting the multivariate data that such analyses generate. As they are interested in the diversity of an environmental sample, we need a proper estimation of the number of species and their abundances. We modified a recently published algorithm to estimate the microbial diversity based on flow cytometry data. After giving a brief sketch of the problem setup, we will review this algorithm alongside its various implementations. Moreover we will present our current implementation combined with future challenges we foresee.

The development cost-effective life support technologies is a highly relevant topic for space biology. Currently, food and water supply during space flights is currently restricted by technical and economic constraints: daily water consumption of an average crew of 6 members is about 72 L, with an estimated cost of 2,160,000 d-1. To reduce these costs and sustain long term space missions, the European Space Agency designed MELiSSA, an artificial ecosystem based on 5 compartments for the recycling gas, liquid and solid waste (Lasseur et al., 2011). In the CI stage, crew and inedible solid waste is fermented by thermophilic anaerobic bacteria, producing volatile fatty acids (VFAs), CO2 and ammonium (NH4+). In the CII compartment the VFAs are converted into edible biomass, using the photoheterotroph Rodospirillum rubrum. Afterwards, the nitrifying CIII unit converts toxic levels of ammonia/ammonium into nitrate, which enables the effluent to be fed to the photoautotrohopic CIV stage, that provides food and oxygen for the crew (Godia et al., 2002). The highest nitrogen flux in a Life Support System is human urine. As nitrate is the preferred form of nitrogen fertilizer for hydroponic plant cultivation, urine nitrification is an essential process in the MELiSSA loop. The development of the Additional Unit for Water Treatment or Urine NItrification ConsortiUM (UNICUM) requires the selection and characterization of the microorganisms that will be used. The key microorganisms in the biological treatment of urine are heterotrophs, for the hydrolysis of urea into ammonia and carbon dioxide, Ammonia Oxidizing Bacteria (AOB), for the ammonia oxidation into nitrite and Nitrite Oxidizing Bacteria (NOB), for the conversion of nitrite into nitrate. The strains were selected according to predefined safety (non sporogenic and BSL 1) and metabolic (Ks, μmax) criteria. To evaluate functional consortia for space applications, ureolysis, nitritation and nitratation of the selected microorganisms and synthetic communities were elucidated. Additionally, urine is a matrix with a high salt content. Unhydrolised urine's EC ranges from 1.1 to 33.9 mS/cm, the mean value being 21.5 mS/cm (Marickar, 2010), while hydrolysed urine can reach higher levels, up to 75 mS/cm. This conditions could inhibit microbial metabolism, therefore the effect of salinity on urine nitrification was also elucidated.

Marine methylotrophs play a key role in the global carbon cycle by metabolizing reduced one-carbon compounds that are found in high concentrations in marine environments. Genome, physiology and diversity studies have been greatly facilitated by the numerous model organisms brought into culture. However, the availability of marine representatives remains poor. Here, we report the isolation of four novel species from North Sea sediment enrichments closely related to the Alphaproteobacterium Methyloceanibacter caenitepidi. Each of the newly isolated Methyloceanibacter species exhibited a clear genome sequence divergence which was reflected in physiological differences. Notably one strain R-67174 was capable of oxidizing methane as sole source of carbon and energy using solely a soluble methane monooxygenase and represents the first marine Alphaproteobacterial methanotroph brought into culture. Differences in maximum cell density of >1.5 orders of magnitude were observed. Furthermore, three strains were capable of producing nitrous oxide from nitrate. Together, these findings highlight the metabolic and physiologic variability within closely related Methyloceanibacter species and provide a new understanding of the physiological basis of marine methylotrophy.