Mineral substrate quality determines the initial soil microbial development in front of the Nordenskiöldbreen, Svalbard.

Substrate geochemistry is an important factor influencing early microbial development after glacial retreat on nutrient-poor geological substrates in the High Arctic. It is often difficult to separate substrate influence from climate because study locations are distant. Our study in the retreating Nordenskiöldbreen (Svalbard) is one of the few to investigate biogeochemical and microbial succession in two adjacent forefields, which share the same climatic conditions but differ in their underlying geology. The northern silicate forefield evolved in a classical chronosequence, where most geochemical and microbial parameters increased gradually with time. In contrast, the southern carbonate forefield exhibited high levels of nutrients and microbial biomass at the youngest sites, followed by a significant decline and then a gradual increase, which caused a rearrangement in the species and functional composition of the bacterial and fungal communities. This shuffling in the early stages of succession suggests that high nutrient availability in the bedrock could have accelerated early soil succession after deglaciation and thereby promoted more rapid stabilization of the soil and production of higher quality organic matter. Most chemical parameters and bacterial taxa converged with time, while fungi showed no clear pattern.

Ammonia oxidation and nitrate reduction marker genes are key indicators of nitrogen losses in temperate forest catchments.

Chronic nitrogen inputs can alleviate N limitation and potentially impose N losses in forests, indicated by soil enrichment in 15 N over 14 N. However, the complexity of the nitrogen cycle hinders accurate quantification of N fluxes. Simultaneously, soil ecologists are striving to find meaningful indicators to characterise the "openness" of the nitrogen cycle. We integrate soil δ15 N with constrained ecosystem N losses and the functional gene potential of the soil microbiome in 14 temperate forest catchments. We show that N losses are associated with soil δ15 N and that δ15 N scales with the abundance of soil bacteria. The abundance of the archaeal amoA gene, representing the first step in nitrification (ammonia oxidation to nitrite), followed by the abundance of narG and napA genes, associated with the first step in denitrification (nitrate reduction to nitrite), explains most of the variability in soil δ15 N. These genes are more informative than the denitrification genes nirS and nirK, which are directly linked to N2 O production. Nitrite formation thus appears to be the critical step associated with N losses. Furthermore, we show that the genetic potential for ammonia oxidation and nitrate reduction is representative of forest soil 15 N enrichment and thus indicative of ecosystem N losses.

Multiple environmental factors, but not nutrient addition, directly affect wet grassland soil microbial community structure: a mesocosm study.

Nutrient addition may change soil microbial community structure, but soil microbes must simultaneously contend with other, interacting factors. We studied the effect of soil type (peat, mineral), water level (low, high), and nutrient addition (unfertilized, fertilized) on wet grassland soil microbial community structure in both vegetated and un-vegetated soils after five years of treatment application in a mesocosm, using Illumina sequencing of the bacterial V4 region of the small ribosomal sub-units. Soil type, water level, and plant presence significantly affected the soil microbial structure, both singly and interactively. Nutrient addition did not directly impact microbiome structure, but acted indirectly by increasing plant biomass. The abundance of possible plant growth promoting bacteria and heterotrophic bacteria indicates the importance of bacteria that promote plant growth. Based on our results, a drier and warmer future would result in nutrient-richer conditions and changes to microbial community structure and total microbial biomass and/or abundances, with wet grasslands likely switching from areas acting as C sinks to C sources.

Microbiome assembly in thawing permafrost and its feedbacks to climate.

The physical and chemical changes that accompany permafrost thaw directly influence the microbial communities that mediate the decomposition of formerly frozen organic matter, leading to uncertainty in permafrost-climate feedbacks. Although changes to microbial metabolism and community structure are documented following thaw, the generality of post-thaw assembly patterns across permafrost soils of the world remains uncertain, limiting our ability to predict biogeochemistry and microbial community responses to climate change. Based on our review of the Arctic microbiome, permafrost microbiology, and community ecology, we propose that Assembly Theory provides a framework to better understand thaw-mediated microbiome changes and the implications for community function and climate feedbacks. This framework posits that the prevalence of deterministic or stochastic processes indicates whether the community is well-suited to thrive in changing environmental conditions. We predict that on a short timescale and following high-disturbance thaw (e.g., thermokarst), stochasticity dominates post-thaw microbiome assembly, suggesting that functional predictions will be aided by detailed information about the microbiome. At a longer timescale and lower-intensity disturbance (e.g., active layer deepening), deterministic processes likely dominate, making environmental parameters sufficient for predicting function. We propose that the contribution of stochastic and deterministic processes to post-thaw microbiome assembly depends on the characteristics of the thaw disturbance, as well as characteristics of the microbial community, such as the ecological and phylogenetic breadth of functional guilds, their functional redundancy, and biotic interactions. These propagate across space and time, potentially providing a means for predicting the microbial forcing of greenhouse gas feedbacks to global climate change.

Fungi in Permafrost-Affected Soils of the Canadian Arctic: Horizon- and Site-Specific Keystone Taxa Revealed by Co-Occurrence Network.

Permafrost-affected soil stores a significant amount of organic carbon. Identifying the biological constraints of soil organic matter transformation, e.g., the interaction of major soil microbial soil organic matter decomposers, is crucial for predicting carbon vulnerability in permafrost-affected soil. Fungi are important players in the decomposition of soil organic matter and often interact in various mutualistic relationships during this process. We investigated four different soil horizon types (including specific horizons of cryoturbated soil organic matter (cryoOM)) across different types of permafrost-affected soil in the Western Canadian Arctic, determined the composition of fungal communities by sequencing (Illumina MPS) the fungal internal transcribed spacer region, assigned fungal lifestyles, and by determining the co-occurrence of fungal network properties, identified the topological role of keystone fungal taxa. Compositional analysis revealed a significantly higher relative proportion of the litter saprotroph Lachnum and root-associated saprotroph Phialocephala in the topsoil and the ectomycorrhizal close-contact exploring Russula in cryoOM, whereas Sites 1 and 2 had a significantly higher mean proportion of plant pathogens and lichenized trophic modes. Co-occurrence network analysis revealed the lowest modularity and average path length, and highest clustering coefficient in cryoOM, which suggested a lower network resistance to environmental perturbation. Zi-Pi plot analysis suggested that some keystone taxa changed their role from generalist to specialist, depending on the specific horizon concerned, Cladophialophora in topsoil, saprotrophic Mortierella in cryoOM, and Penicillium in subsoil were classified as generalists for the respective horizons but specialists elsewhere. The litter saprotrophic taxon Cadophora finlandica played a role as a generalist in Site 1 and specialist in the rest of the sites. Overall, these results suggested that fungal communities within cryoOM were more susceptible to environmental change and some taxa may shift their role, which may lead to changes in carbon storage in permafrost-affected soil.

Decomposition of peatland DOC affected by root exudates is driven by specific r and K strategic bacterial taxa.

In peatlands, decomposition of organic matter is limited by harsh environmental conditions and low decomposability of the plant material. Shifting vegetation composition from Sphagnum towards vascular plants is expected in response to climate change, which will lead to increased root exudate flux to the soil and stimulation of microbial growth and activity. We aimed to evaluate the effect of root exudates on the decomposition of recalcitrant dissolved organic carbon (DOC) and to identify microorganisms involved in this process. The exudation was mimicked by an addition of a mixture of 13C labelled compounds into the recalcitrant DOC in two realistic levels; 2% and 5% of total DOC and peatland porewater with added root exudates was incubated under controlled conditions in the lab. The early stage of incubation was characterized by a relative increase of r-strategic bacteria mainly from Gammaproteobacteria and Bacteriodetes phyla within the microbial community and their preferential use of the added compounds. At the later stage, Alphaproteobacteria and Acidobacteria members were the dominating phyla, which metabolized both the transformed 13C compounds and the recalcitrant DOC. Only higher exudate input (5% of total DOC) stimulated decomposition of recalcitrant DOC compared to non-amended control. The most important taxa with a potential to decompose complex DOC compounds were identified as: Mucilaginibacter (Bacteriodetes), Burkholderia and Pseudomonas (Gammaproteobacteria) among r-strategists and Bryocella and Candidatus Solibacter (Acidobacteria) among K-strategists. We conclude that increased root exudate inputs and their increasing C/N ratio stimulate growth and degradation potential of both r-strategic and K-strategic bacteria, which make the system more dynamic and may accelerate decomposition of peatland recalcitrant DOC.

Microbiome structure and functional potential in permafrost soils of the Western Canadian Arctic.

Substantial amounts of topsoil organic matter (OM) in Arctic Cryosols have been translocated by the process of cryoturbation into deeper soil horizons (cryoOM), reducing its decomposition. Recent Arctic warming deepens the Cryosols´ active layer, making more topsoil and cryoOM carbon accessible for microbial transformation. To quantify bacteria, archaea and selected microbial groups (methanogens - mcrA gene and diazotrophs - nifH gene) and to investigate bacterial and archaeal diversity, we collected 83 soil samples from four different soil horizons of three distinct tundra types located in Qikiqtaruk (Hershel Island, Western Canada). In general, the abundance of bacteria and diazotrophs decreased from topsoil to permafrost, but not for cryoOM. No such difference was observed for archaea and methanogens. CryoOM was enriched with oligotrophic (slow-growing microorganism) taxa capable of recalcitrant OM degradation. We found distinct microbial patterns in each tundra type: topsoil from wet-polygonal tundra had the lowest abundance of bacteria and diazotrophs, but the highest abundance of methanogens. Wet-polygonal tundra, therefore, represented a hotspot for methanogenesis. Oligotrophic and copiotrophic (fast-growing microorganism) genera of methanogens and diazotrophs were distinctly distributed in topsoil and cryoOM, resulting in different rates of nitrogen flux into these horizons affecting OM vulnerability and potential CO2 and CH4 release.

Bacteria but not fungi respond to soil acidification rapidly and consistently in both a spruce and beech forest.

Anthropogenically enhanced atmospheric sulphur (S) and nitrogen (N) deposition has acidified and eutrophied forest ecosystems worldwide. However, both S and N mechanisms have an impact on microbial communities and the consequences for microbially driven soil functioning differ. We conducted a two-forest stand (Norway spruce and European beech) field experiment involving acidification (sulphuric acid addition) and N (ammonium nitrate) loading and their combination. For 4 years, we monitored separate responses of soil microbial communities to the treatments and investigated the relationship to changes in the activity of extracellular enzymes. We observed that acidification selected for acidotolerant and oligotrophic taxa of Acidobacteria and Actinobacteria decreased bacterial community richness and diversity in both stands in parallel, disregarding their original dissimilarities in soil chemistry and composition of microbial communities. The shifts in bacterial community influenced the stoichiometry and magnitude of enzymatic activity. The bacterial response to experimental N addition was much weaker, likely due to historically enhanced N availability. Fungi were not influenced by any treatment during 4-year manipulation. We suggest that in the onset of acidification when fungi remain irresponsive, bacterial reaction might govern the changes in soil enzymatic activity.

Coordination Behavior of 1,4-Disubstituted Cyclen Endowed with Phosphonate, Phosphonate Monoethylester, and H-Phosphinate Pendant Arms.

Three 1,4,7,10-tetraazacyclododecane-based ligands disubstituted in 1,4-positions with phosphonic acid, phosphonate monoethyl-ester, and H-phosphinic acid pendant arms, 1,4-H4do2p, 1,4-H2do2pOEt, and 1,4-H2Bn2do2pH, were synthesized and their coordination to selected metal ions, Mg(II), Ca(II), Mn(II), Zn(II), Cu(II), Eu(III), Gd(III), and Tb(III), was investigated. The solid-state structure of the phosphonate ligand, 1,4-H4do2p, was determined by single-crystal X-ray diffraction. Protonation constants of the ligands and stability constants of their complexes were obtained by potentiometry, and their values are comparable to those of previously studied analogous 1,7-disubstitued cyclen derivatives. The Gd(III) complex of 1,4-H4do2p is ~1 order of magnitude more stable than the Gd(III) complex of the 1,7-analogue, probably due to the disubstituted ethylenediamine-like structural motif in 1,4-H4do2p enabling more efficient wrapping of the metal ion. Stability of Gd(III)-1,4-H2do2pOEt and Gd(III)-H2Bn2do2pH complexes is low and the constants cannot be determined due to precipitation of the metal hydroxide. Protonations of the Cu(II), Zn(II), and Gd(III) complexes probably takes place on the coordinated phosphonate groups. Complexes of Mn(II) and alkali-earth metal ions are significantly less stable and are not formed in acidic solutions. Potential presence of water molecule(s) in the coordination spheres of the Mn(II) and Ln(III) complexes was studied by variable-temperature NMR experiments. The Mn(II) complexes of the ligands are not hydrated. The Gd(III)-1,4-H4do2p complex undergoes hydration equilibrium between mono- and bis-hydrated species. Presence of two-species equilibrium was confirmed by UV-Vis spectroscopy of the Eu(III)-1,4-H4do2p complex and hydration states were also determined by luminescence measurements of the Eu(III)/Tb(III)-1,4-H4do2p complexes.

Spatial heterogeneity of belowground microbial communities linked to peatland microhabitats with different plant dominants.

Peatland vegetation is composed mostly of mosses, graminoids and ericoid shrubs, and these have a distinct impact on peat biogeochemistry. We studied variation in soil microbial communities related to natural peatland microhabitats dominated by Sphagnum, cotton-grass and blueberry. We hypothesized that such microhabitats will be occupied by structurally and functionally different microbial communities, which will vary further during the vegetation season due to changes in temperature and photosynthetic activity of plant dominants. This was addressed using amplicon-based sequencing of prokaryotic and fungal rDNA and qPCR with respect to methane-cycling communities. Fungal communities were highly microhabitat-specific, while prokaryotic communities were additionally directed by soil pH and total N content. Seasonal alternations in microbial community composition were less important; however, they influenced the abundance of methane-cycling communities. Cotton-grass and blueberry bacterial communities contained relatively more α-Proteobacteria but less Chloroflexi, Fibrobacteres, Firmicutes, NC10, OD1 and Spirochaetes than in Sphagnum. Methanogens, syntrophic and anaerobic bacteria (i.e. Clostridiales, Bacteroidales, Opitutae, Chloroflexi and Syntrophorhabdaceae) were suppressed in blueberry indicating greater aeration that enhanced abundance of fungi (mainly Archaeorhizomycetes) and resulted in the highest fungi-to-bacteria ratio. Thus, microhabitats dominated by different vascular plants are inhabited by unique microbial communities, contributing greatly to spatial functional diversity within peatlands.

Effects of food-borne ZnO nanoparticles on intestinal microbiota of common carp (Cyprinus carpio L.).

Ingestion of nanoparticles (NPs) with antimicrobial properties may disrupt the balance of intestinal microbiota. To investigate the effects of zinc oxide (ZnO) NPs on intestinal flora, common carp Cyprinus carpio were fed a commercial feed containing 500 mg kg-1 ZnO NPs for 6 weeks and compared to a control group receiving a similar feed-only regime. Sequencing data were analyzed both in individual fish and in pooled samples. Sequencing of 16S rRNA encoding gene of individual specimens revealed high variation in intestinal microbial composition. Assessment of pooled results can obscure high individual variation in data. ZnO NPs consumption was not associated with a significant difference in the intestinal microbial community compared to untreated controls. Our results indicated a high individual variation in the intestinal microbiome, which may further point out the importance of functional study over microbial composition to address nanomaterials-microbiome relationship.

Correction to: Hunters or farmers? Microbiome characteristics help elucidate the diet composition in an aquatic carnivorous plant.

AbstractFollowing publication of the original article [1], the author reported an error in Fig. 3.

Retraction Statement: Comparison of nitrogen inputs and accumulation in 210 Pb-dated peat cores: Evidence for biological N2 -fixation in Central European peatlands despite decades of atmospheric N pollution.

"Comparison of nitrogen inputs and accumulation in 210 Pb-dated peat cores: Evidence for biological N2 -fixation in Central European peatlands despite decades of atmospheric N pollution" https://doi.org/10.1111/gcb.14505, by Martin Novak, Melanie A. Vile, Jan Curik, Bohuslava Cejkova, Jiri Barta, Marketa Stepanova, Ivana Jackova, Frantisek Buzek, Leona Bohdalkova, Eva Prechova, Frantisek Veselovsky, Marie Adamova, Ivana Valkova and Arnost Komarek. The above article, first published online in Wiley Online Library (wileyonlinelibrary.com) in Global Change Biology, has been retracted by agreement between the authors, the journal Editor-in-Chief, Stephen P. Long, and John Wiley & Sons Ltd. Since publication of the above article, it was brought to the attention of the authors that the peat accretion rates violate reasonable ranges of peatland C/N/P stoichiometry, placing the quantitative conclusions of the article in serious error. The authors apologize for any inconvenience the publication of this work may have caused our readers. REFERENCE Novak, M., Vile, M. A., Cejkova, B., Barta, J., Stepanova, M., Jackova, I., Buzek, F., Bohdalkova, L., Prechova, E., Veselovsky, F., Adamova, M., Valkova, I., & Komarek, A. (2018). Comparison of nitrogen inputs and accumulation in 210 Pb-dated peat cores: Evidence for biological N2 -fixation in Central European peatlands despite decades of atmospheric N pollution. Global Change Biology.. https://doi.org/10.1111/gcb.14505.

Hunters or farmers? Microbiome characteristics help elucidate the diet composition in an aquatic carnivorous plant.

BACKGROUND: Utricularia are rootless aquatic carnivorous plants which have recently attracted the attention of researchers due to the peculiarities of their miniaturized genomes. Here, we focus on a novel aspect of Utricularia ecophysiology-the interactions with and within the complex communities of microorganisms colonizing their traps and external surfaces. RESULTS: Bacteria, fungi, algae, and protozoa inhabit the miniature ecosystem of the Utricularia trap lumen and are involved in the regeneration of nutrients from complex organic matter. By combining molecular methods, microscopy, and other approaches to assess the trap-associated microbial community structure, diversity, function, as well as the nutrient turn-over potential of bacterivory, we gained insight into the nutrient acquisition strategies of the Utricularia hosts. CONCLUSIONS: We conclude that Utricularia traps can, in terms of their ecophysiological function, be compared to microbial cultivators or farms, which center around complex microbial consortia acting synergistically to convert complex organic matter, often of algal origin, into a source of utilizable nutrients for the plants.

A plant-microbe interaction framework explaining nutrient effects on primary production.

In most terrestrial ecosystems, plant growth is limited by nitrogen and phosphorus. Adding either nutrient to soil usually affects primary production, but their effects can be positive or negative. Here we provide a general stoichiometric framework for interpreting these contrasting effects. First, we identify nitrogen and phosphorus limitations on plants and soil microorganisms using their respective nitrogen to phosphorus critical ratios. Second, we use these ratios to show how soil microorganisms mediate the response of primary production to limiting and non-limiting nutrient addition along a wide gradient of soil nutrient availability. Using a meta-analysis of 51 factorial nitrogen-phosphorus fertilization experiments conducted across multiple ecosystems, we demonstrate that the response of primary production to nitrogen and phosphorus additions is accurately predicted by our stoichiometric framework. The only pattern that could not be predicted by our original framework suggests that nitrogen has not only a structural function in growing organisms, but also a key role in promoting plant and microbial nutrient acquisition. We conclude that this stoichiometric framework offers the most parsimonious way to interpret contrasting and, until now, unresolved responses of primary production to nutrient addition in terrestrial ecosystems.

Temperature response of permafrost soil carbon is attenuated by mineral protection.

Climate change in Arctic ecosystems fosters permafrost thaw and makes massive amounts of ancient soil organic carbon (OC) available to microbial breakdown. However, fractions of the organic matter (OM) may be protected from rapid decomposition by their association with minerals. Little is known about the effects of mineral-organic associations (MOA) on the microbial accessibility of OM in permafrost soils and it is not clear which factors control its temperature sensitivity. In order to investigate if and how permafrost soil OC turnover is affected by mineral controls, the heavy fraction (HF) representing mostly MOA was obtained by density fractionation from 27 permafrost soil profiles of the Siberian Arctic. In parallel laboratory incubations, the unfractionated soils (bulk) and their HF were comparatively incubated for 175 days at 5 and 15°C. The HF was equivalent to 70 ± 9% of the bulk CO2 respiration as compared to a share of 63 ± 1% of bulk OC that was stored in the HF. Significant reduction of OC mineralization was found in all treatments with increasing OC content of the HF (HF-OC), clay-size minerals and Fe or Al oxyhydroxides. Temperature sensitivity (Q10) decreased with increasing soil depth from 2.4 to 1.4 in the bulk soil and from 2.9 to 1.5 in the HF. A concurrent increase in the metal-to-HF-OC ratios with soil depth suggests a stronger bonding of OM to minerals in the subsoil. There, the younger 14 C signature in CO2 than that of the OC indicates a preferential decomposition of the more recent OM and the existence of a MOA fraction with limited access of OM to decomposers. These results indicate strong mineral controls on the decomposability of OM after permafrost thaw and on its temperature sensitivity. Thus, we here provide evidence that OM temperature sensitivity can be attenuated by MOA in permafrost soils.

Heterotrophic N2-fixation contributes to nitrogen economy of a common wetland sedge, Schoenoplectus californicus.

A survey of the ecological variability within 52 populations of Schoenoplectus californicus (C.A. Mey.) Soják across its distributional range revealed that it is commonly found in nitrogen (N) limited areas, but rarely in phosphorus limited soils. We explored the hypothesis that S. californicus supplements its nitrogen demand by bacterial N2-fixation processes associated with its roots and rhizomes. We estimated N2-fixation of diazotrophs associated with plant rhizomes and roots from several locations throughout the species' range and conducted an experiment growing plants in zero, low, and high N additions. Nitrogenase activity in rhizomes and roots was measured using the acetylene reduction assay. The presence of diazotrophs was verified by the detection of the nifH gene. Nitrogenase activity was restricted to rhizomes and roots and it was two orders of magnitude higher in the latter plant organs (81 and 2032 nmol C2H4 g DW-1 d-1, respectively). Correspondingly, 40x more nifH gene copies were found on roots compared to rhizomes. The proportion of the nifH gene copies in total bacterial DNA was positively correlated with the nitrogenase activity. In the experiment, the contribution of fixed N to the plant N content ranged from 13.8% to 32.5% among clones from different locations. These are relatively high values for a non-cultivated plant and justify future research on the link between N-fixing bacteria and S. californicus production.

Comparison of the impacts of acid and nitrogen additions on carbon fluxes in European conifer and broadleaf forests.

Increased reactive nitrogen (N) loadings to terrestrial ecosystems are believed to have positive effects on ecosystem carbon (C) sequestration. Global "hot spots" of N deposition are often associated with currently or formerly high deposition of sulphur (S); C fluxes in these regions might therefore not be responding solely to N loading, and could be undergoing transient change as S inputs change. In a four-year, two-forest stand (mature Norway spruce and European beech) replicated field experiment involving acidity manipulation (sulphuric acid addition), N addition (NH4NO3) and combined treatments, we tested the extent to which altered soil solution acidity or/and soil N availability affected the concentration of soil dissolved organic carbon (DOC), soil respiration (Rs), microbial community characteristics (respiration, biomass, fungi and bacteria abundances) and enzyme activity. We demonstrated a large and consistent suppression of soil water DOC concentration driven by chemical changes associated with increased hydrogen ion concentrations under acid treatments, independent of forest type. Soil respiration was suppressed by sulphuric acid addition in the spruce forest, accompanied by reduced microbial biomass, increased fungal:bacterial ratios and increased C to N enzyme ratios. We did not observe equivalent effects of sulphuric acid treatments on Rs in the beech forest, where microbial activity appeared to be more tightly linked to N acquisition. The only changes in C cycling following N addition were increased C to N enzyme ratios, with no impact on C fluxes (either Rs or DOC). We conclude that C accumulation previously attributed solely to N deposition could be partly attributable to their simultaneous acidification.

Author Correction: Microbial communities with distinct denitrification potential in spruce and beech soils differing in nitrate leaching.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Assessment of the effect of left atrial cryoablation enhanced by ganglionated plexi ablation in the treatment of atrial fibrillation in patients undergoing open heart surgery.

BACKGROUND: The aim of our study was to investigate, whether enhancement of left atrial cryoablation by ablation of the autonomic nervous system of left atrium leads to influencing the outcomes of surgical treatment of atrial fibrillation in patients with structural heart disease undergoing open-heart surgery. METHODS: The observed patient file consisted of 100 patients, who have undergone a combined open-heart surgery at our department between July 2012 and December 2014. The patients were indicated for the surgical procedure due to structural heart disease, and suffered from paroxysmal, persistent, or long-standing persistent atrial fibrillation. In all cases, left atrial cryoablation was performed in the extent of isolation of pulmonary veins, box lesion, connecting lesion with mitral annulus, amputation of the left atrial appendage and connecting lesion of the appendage base with left pulmonary veins. Furthermore, 35 of the patients underwent mapping and radiofrequency ablation of ganglionated plexi, together with discision and ablation of the ligament of Marshall (Group GP). A control group was consisted of 65 patients without ganglionated plexi intervention (Group LA). The main primary outcome was establishment and duration of sinus rhythm in the course of one-year follow-up. RESULTS: Evaluation of the number of patients with a normal sinus rhythm in per cent has shown comparable values in both groups (Group GP - 93.75%, Group LA - 86.67%, p = 0.485); comparable results were also observed in patients with normal sinus rhythm without anti-arrhythmic treatment in the 12th month (Group GP - 50%, Group LA - 47%, p = 0.306). We have not observed any relation between the recurrence of atrial fibrillation and the presence of a mitral valve surgery, or between the presence of a mitral and tricuspid valves surgery and between the left atrial diameter > 50 mm. CONCLUSIONS: Enhancement of left atrial cryoablation by gangionated plexi ablation did not influence the outcomes of surgical ablation due to atrial fibrillation in our population in the course of 12-month follow-up. TRIAL REGISTRATION: The study was approved retrospectively by the Ethics Committee of the University Hospital Ostrava ( reference number 867/2016).