Environmental drivers of the composition and diversity of the herb layer in mixed temperate forests in Hungary

Herbaceous understory vegetation is an important part of temperate forested ecosystems, the diversity and composition of which are strongly dependent on the conditions of the forest stand and the landscape. The aim of this study was to find the most important environmental drivers influencing understory herb layer species composition (explored with multivariate analysis), and richness and cover (analysed by linear modelling) in managed mixed forests in West Hungary. Our detailed inventory showed that the most important factors increasing the diversity and cover of the understory are light, tree species richness, and landscape diversity. Composition is also mainly influenced by light conditions and tree species richness, with minor effects of tree species composition, soil texture, and moss cover. As the strongest influencing factors are closely linked to stand structure and tree species composition, they can either directly or indirectly be altered by forest management. In the studied region, heterogeneous light conditions and canopy structure, the maintenance of tree species richness and forest continuity are key elements for the conservation of forest herbs. Forestry that maintains continuous forest cover and the tree selection management system can better provide these conditions than the presently widely used shelterwood management system. © 2016 Springer Science+Business Media Dordrech

Environmental drivers of the bryophyte propagule bank and its comparison with forest-floor assemblage in Central European temperate mixed forests

Species richness, composition and abundance of the bryophyte diaspore bank of Central European temperate mixed forests were compared with the forest-floor bryophyte assemblage. The impact of environmental variables and anthropogenic disturbances, including tree species composition, stand structure, microclimate, light conditions, soil and litter properties, management history, and landscape properties, potentially influencing bryophyte diaspore bank assemblages were explored. Thirty-four, 70–100 years old mixed stands with differing tree species composition were examined in the O˝ rség National Park, Western Hungary. The diaspore bank was studied by soil collection and cultivation, and data were analysed by multivariate methods. Contrary to the forest-floor bryophyte assemblage, where substrate availability, tree species composition and stand structure were the most influential environmental variables, the composition and abundance of the diaspore bank was mainly affected by site conditions (microclimate, litter and soil properties). Species richness of the bryophyte diaspore bank was lower than that of the forest-floor bryophyte assemblage. Short-lived mosses (colonists, short-lived shuttles) were dominant in the diaspore bank, as opposed to the forest-floor bryophyte community, where perennial mosses dominated. In the studied forests, the importance of the bryophyte diaspore bank was relatively low in the regeneration and maintenance of the forest-floor bryophyte vegetation

Microbiological investigations on the water of a thermal bath at Budapest

Thermal baths are unique aquatic environments combining a wide variety of natural and anthropogenic ecological factors, which also appear in their microbiological state. There is limited information on the microbiology of thermal baths in their complexity, tracking community shifts from the thermal wells to the pools. In the present study, the natural microbial community of well and pool waters in Gellért bath was studied in detail by cultivation-based techniques. To isolate bacteria, 10% R2A and minimal synthetic media (with “bath water”) with agar–agar and gellan gum were used after prolonged incubation time; moreover, polyurethane blocks covered with media were also applied. Strains were identified by sequencing their 16S rRNA gene after grouping them by amplified rDNA restriction analysis. From each sample, the dominance of Alphaproteobacteria was characteristic though their diversity differed among samples. Members of Actinobacteria, Firmicutes, Beta- and Gamma-proteobacteria, Deinococcus–Thermus, and Bacteroidetes were also identified. Representatives of Deinococcus–Thermus phylum appeared only in the pool water. The largest groups in the pool water belonged to the Tistrella and Chelatococcus genera. The most dominant member in the well water was a new taxon, its similarity to Hartmannibacter diazotrophicus as closest relative was 93.93%

A közösségi anyagcsere vizsgálata anaerob deklorináció során = Investigations on the community metabolism in anaerobe dechlorination

A rövidszénláncú alifás klórozott szénhidrogének gyakori talajvízszennyezők hazánkban. A perklóretén, triklóretén biológiai bontása hatékony folyamat, mégis nagy sebességkülönbségek jellemzők különböző szennyezett területeken. A reduktív deklorinációban a klórozott vegyületek elektronakceptorok, elektrondonor a hidrogén, vagy kis molekulatömegű szerves vegyületek. A folyamat elindulásához a deklorináló baktériumoknak felül kell kerekedniük a kompetítor mikrobákon, amelyek szintén hidrogént és szerves vegyületeket hasznosítanak. Szennyezett területekről származó mikrobaközösségek szerkezetét, tagjainak szerepét laboratóriumi körülmények között polifázikus módszerekkel vizsgáltuk, új molekuláris technikákat vezettünk be a mikrobák közötti anyagcsere-kapcsolatok megértésére. Megállapítottuk, hogy sikeres deklorináló közösségben jellemző a Dehalococcoides ethenogenes dominanciája; a mikrobiális diverzitás csökkenése. A lebontás folyamatát fermentáló szervezetek jelenléte lassítja, akárcsak a kometabolikus partnerek gátlása. Hatékony bontás során biofilm kialakulása jellmező és elengedhetetlen kellő mennyiségű hozzáférhető szerves anyag jelenléte. Négy új módszert (MDA, SNuPE, SEM és FISH) optimáltunk a deklorináló mikroba közösség vizsgálatára. Megállapítottuk, hogy a valós aktivitással jobban korreláló RNS alapú vizsgálatok szükségesek a deklorinációban résztvevő mikrobiális kapcsolatok feltárásához. | Chlorinated short chain aliphatic hydrocarbons are common groundwater pollutants in Hungary. Biological decomposition of perchloroethene and trichloroethene is effective process, though speed of decomposition extremely differ in different sites. At reductive dechlorination chlorinated hydrocarbons serve as electron acceptors, H2 or small organic compounds act as donors. At startup of degradation dechlorinating microbes have to outcompete compeptitor microbes utilising similarly H2 and organic compounds. Microbial communities originating from different polluted sites and the role of their members in the community dechlorinating metabolism were investigated under controlled laboratory microcosm experiments using polyphasic approach, and by introducing new techniques. It could be determined that effective dechlorinating communities are characterised by the dominance of Dehalococcoides ethenogenes, and a simplification of the original diversity. The presence of fermenting microbes retards the speed of degradation; the inhibition of co-metabolic partners acts similarly. Effective degradation is characterised by Dehalococcoides spp. biofilm formation, and presence of adequte available organic compounds is indispensable. Four novel methods (MDA, SNuPE, SEM and FISH) were optimised for the investigation of dechlorinating communities. RNA based investigations better correlate real activities thus their use is indispensable in the investigation of microbial metabolic interactions

Habitat distribution of the genus Belliella in continental waters and the description of Belliella alkalica sp. nov., Belliella calami sp. nov. and Belliella filtrata sp. nov.

The genus Belliella belongs to the family Cyclobacteriaceae (order Cytophagales , phylum Bacteroidota ) and harbours aerobic chemoheterotrophic bacteria. Members of this genus were isolated from various aquatic habitats, and our analysis based on global amplicon sequencing data revealed that their relative abundance can reach up to 5–10 % of the bacterioplankton in soda lakes and pans. Although a remarkable fraction of the most frequent genotypes that we identified from continental aquatic habitats is still uncultured, five new alkaliphilic Belliella strains were characterized in detail in this study, which were isolated from three different soda lakes and pans of the Carpathian Basin (Hungary). Cells of all strains were Gram-stain-negative, obligate aerobic, rod-shaped, non-motile and non-spore-forming. The isolates were oxidase- and catalase-positive, red-coloured, but did not contain flexirubin-type pigments; they formed bright red colonies that were circular, smooth and convex. Their major isoprenoid quinone was MK-7 and the predominant fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 containing C16 : 1  ω6c and/or C16 : 1  ω7c. The polar lipid profiles contained phosphatidylethanolamine, an unidentified aminophospholipid, an unidentified glycolipid, and several unidentified lipids and aminolipids. Based on whole-genome sequences, the DNA G+C content was 37.0, 37.1 and 37.8 mol % for strains R4-6T, DMA-N-10aT and U6F3T, respectively. The distinction of three new species was confirmed by in silico genomic comparison. Orthologous average nucleotide identity (<85.4 %) and digital DNA–DNA hybridization values (<38.9 %) supported phenotypic, chemotaxonomic and 16S rRNA gene sequence data and, therefore, the following three novel species are proposed: Belliella alkalica sp. nov. (represented by strains R4-6T=DSM 111903T=JCM 34281T=UCCCB122T and S4-10), Belliella calami sp. nov. (DMA-N-10aT=DSM 107340T=JCM 34280T=UCCCB121T) and Belliella filtrata sp. nov. (U6F3T=DSM 111904T=JCM 34282T=UCCCB123T and U6F1). Emended descriptions of species Belliella aquatica , Belliella baltica , Belliella buryatensis , Belliella kenyensis and Belliella pelovolcani are also presented

Radioactive environment adapted bacterial communities constituting the biofilms of hydrothermal spring caves (Budapest, Hungary)

The thermal waters of Gellért Hill discharge area of the Buda Thermal Karst System (Hungary) are characterized by high (up to 1000 Bq/L) 222Rn-activity due to the radium-accumulating biogeochemical layers. Samples were taken from these ferruginous and calcareous layers developed on spring cave walls and water surface. Accumulation of potentially toxic metals (e.g. As, Hg, Pb, Sn, Sr, Zn) in the dense extracellular polymeric substance containing bacterial cells and remains was detected by inductively coupled plasma mass spectrometry. The comparison of bacterial phylogenetic diversity of the biofilm samples was performed by high throughput next generation sequencing (NGS). The analysis showed similar sets of mainly unidentified taxa of phyla Chloroflexi, Nitrospirae, Proteobacteria, Planctomycetes; however, large differences were found in their abundance. Cultivation-based method complemented with irradiation assay was performed using 5, 10 and 15 kGy doses of gamma-rays from a 60Co-source to reveal the extreme radiation-resistant bacteria. The phyla Actinobacteria, Firmicutes, Proteobacteria (classes Alpha- Beta- and Gammaproteobacteria), Bacteriodetes and Deinococcus-Thermus were represented among the 452 bacterial strains. The applied irradiation treatments promoted the isolation of 100 different species, involving candidate novel species, as well. The vast majority of the isolates belonged to bacterial taxa previously unknown as radiation-resistant microorganisms. Members of the genera Paracoccus, Marmoricola, Dermacoccus and Kytococcus were identified from the 15 kGy dose irradiated samples. The close relatives of several known radiation-tolerant bacteria were also detected from the biofilm samples, alongside with bacteria capable of detoxification by metal accumulation, adsorption and precipitation in the form of calcium-carbonate which possibly maintain the viability of the habitat. The results suggest the establishment of a unique, extremophilic microbiota in the studied hydrothermal spring caves