Schauerella fraxinea gen. nov., sp. nov., a bacterial species that colonises ash trees tolerant to dieback caused by Hymenoscyphus fraxineus.

The tolerance of ash trees against the pathogen Hymenoscyphus fraxineus seems to be associated with the occurrence of specific microbial taxa on leaves. A group of bacterial isolates, primarily identified on tolerant trees, was investigated with regard to their taxonomic classification and their potential to suppress the ash dieback pathogen. Examination of OGRI values revealed a separate species position.

Genomic evidence for two pathways of formaldehyde oxidation and denitrification capabilities of the species sp. nov.

Three strains (H4-D09, S2-D11 and S9-F39) of a member of the genus attributed to a novel species were isolated from topsoil of temperate grasslands. The genome sequence of the type strain H4-D09 exhibited a complete set of genes required for denitrification as well as methylotrophy. The genome of H4-D09 included genes for two alternative pathways of formaldehyde oxidation.

Genomic Characterization of C2P003-A Specific Member of the Microbiome of Trees Tolerant to Ash Dieback.

Some European ash trees show tolerance towards dieback caused by the invasive pathogen . The microbiome of these trees harbours a range of specific bacterial groups. One of these groups belonging to the species was studied in detail by genome analysis and a plant inoculation trial.

Consumption of NO by sp. nov. Isolated from Decomposing Leaf Litter of (Cav.).

Microorganisms acting as sinks for the greenhouse gas nitrous oxide (NO) are gaining increasing attention in the development of strategies to control NO emissions. Non-denitrifying NO reducers are of particular interest because they can provide a real sink without contributing to NO release. The bacterial strain under investigation (IGB 4-14), isolated in a mesocosm experiment to study the litter decomposition of (Cav.

Physiological and genomic characterisation of Luteimonas fraxinea sp. nov., a bacterial species associated with trees tolerant to ash dieback.

A group of isolates of the genus Luteimonas was characterised, which represented a specific component of the healthy core microbiome of Fraxinus excelsior in forest districts with a high infection rate of H. fraxineus, the causal agent of ash dieback. Based on phylogenomic and phenotypic analyses, a clear differentiation from related Luteimonas species was shown.

sp. nov., a nitrate-reducing bacterium isolated from grassland soil.

A novel strain was isolated from grassland soil that has the potential to assimilate ammonium by the reduction of nitrate in the presence of oxygen. Whole genome sequence analysis revealed the presence of an assimilatory cytoplasmic nitrate reductase gene and the assimilatory nitrite reductase genes which are involved in the sequential reduction of nitrate to nitrite and further to ammonium, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate represents a member of the genus .

Genome-based phylogeny of the genera and and description of subsp. subsp. nov. and subsp. subsp. nov.

The genera and are closely related members of the family . The genus consists of the species originally separated from the genus by gene analysis. Due to the high similarity of the 16S rRNA genes between species of both genera, the taxonomic status is here re-evaluated by a genome-based approach.

Analyzing Ash Leaf-Colonizing Fungal Communities for Their Biological Control of .

The invasive ascomycete has been threatening populations throughout Europe for over two decades. Since the infection and first colonization by the pathogen occurs in leaves, leaf-colonizing microorganisms have been discussed as a barrier and as possible biocontrol agents against the disease. To identify fungal groups with health-supporting potential, we compared the fungal microbiota of compound leaves from susceptible and tolerant ash trees in four ash stands with high exposure.

A Comparative Analysis of Ash Leaf-Colonizing Bacterial Communities Identifies Putative Antagonists of .

In the last few years, the alarming spread of , the causal agent of ash dieback, has resulted in a substantial threat to native ash stands in central and northern Europe. Since leaves and leaf petioles are the primary infection sites, phyllosphere microorganisms are presumed to interact with the pathogen and are discussed as a source of biocontrol agents. We studied compound leaves from susceptible and visible infection-free trees in four ash stands with a high likelihood of infection to assess a possible variation in the bacterial microbiota, depending on the health status of the trees.

Pseudomonas simiae effects on the mycotoxin formation by fusaria and alternaria in vitro and in a wheat field.

Fluorescent pseudomonads colonizing wheat ears have a high antagonistic potential against phytopathogenic fungi. To check this hypothesis, the bacterial antagonist Pseudomonas simiae 9 was spray-inoculated onto the ears of winter wheat in a locally demarcated experimental field plot. Fusarium and Alternaria fungi naturally occurring on the ears and the formation of their mycotoxins in the ripe grains were investigated.

Antagonistic Potential of Fluorescent Pseudomonads Colonizing Wheat Heads Against Mycotoxin Producing Alternaria and Fusaria.

Natural control of phytopathogenic microorganisms is assumed as a priority function of the commensal plant microbiota. In this study, the suitability of fluorescent pseudomonads in the phyllosphere of crop plants as natural control agents was evaluated. Under field conditions, ears of winter wheat were found to be colonized with high consistency and at a high density by pseudomonads at the late milk dough stage.

Antimicrobial Activity of Medicinal Plants Correlates with the Proportion of Antagonistic Endophytes.

Medicinal plants are known to harbor potential endophytic microbes, due to their bioactive compounds. In a first study of ongoing research, endophytic bacteria were isolated from two medicinal plants, and with contrasting antimicrobial activities from the Chatkal Biosphere Reserve of Uzbekistan, and their plant-specific traits involved in biocontrol and plant growth promotion were evaluated. Plant extracts of exhibited a remarkable activity against bacterial and fungal pathogens, whereas extracts of did not exhibit any potential antimicrobial activity.

Characterization of the N2O-producing soil bacterium Rhizobium azooxidifex sp. nov.

In the context of studying the bacterial community involved in nitrogen transformation processes in arable soils exposed to different extents of erosion and sedimentation in a long-term experiment (CarboZALF), a strain was isolated that reduced nitrate to nitrous oxide without formation of molecular nitrogen. The presence of the functional gene nirK, encoding the respiratory copper-containing nitrite reductase, and the absence of the nitrous oxide reductase gene nosZ indicated a truncated denitrification pathway and that this bacterium may contribute significantly to the formation of the important greenhouse gas N2O. Phylogenetic analysis based on the 16S rRNA gene sequence and the housekeeping genes recA and atpD demonstrated that the investigated soil isolate belongs to the genus Rhizobium.

Biochar Treatment Resulted in a Combined Effect on Soybean Growth Promotion and a Shift in Plant Growth Promoting Rhizobacteria.

The application of biochar to soil is considered to have the potential for long-term soil carbon sequestration, as well as for improving plant growth and suppressing soil pathogens. In our study we evaluated the effect of biochar on the plant growth of soybeans, as well as on the community composition of root-associated bacteria with plant growth promoting traits. Two types of biochar, namely, maize biochar (MBC), wood biochar (WBC), and hydrochar (HTC) were used for pot experiments to monitor plant growth.

Fluorescent Pseudomonads in the Phyllosphere of Wheat: Potential Antagonists Against Fungal Phytopathogens.

Fluorescent pseudomonads isolated from wheat leaves were characterized regarding their antagonistic potential and taxonomy in relation to protect crop plants from infestation by Fusarium and Alternaria fungi causing diseases in wheat. Using a dual culture assay, inhibition of fungal growth was found for 40 isolates of 175 fluorescent pseudomonads. Twenty-two of the antagonists were able to suppress strains of Fusarium as well as Alternaria.

Taxonomic characterisation of Proteus terrae sp. nov., a N2O-producing, nitrate-ammonifying soil bacterium.

In the context of studying the influence of N-fertilization on N2 and N2O flux rates in relation to the soil bacterial community composition in fen peat grassland, a group of bacterial strains was isolated that performed dissimilatory nitrate reduction to ammonium and concomitantly produced N2O. The amount of nitrous oxide produced was influenced by the C/N ratio of the medium. The potential to generate nitrous oxide was increased by higher availability of nitrate-N.

Characterization of heterotrophic nitrifying bacteria with respiratory ammonification and denitrification activity--description of Paenibacillus uliginis sp. nov., an inhabitant of fen peat soil and Paenibacillus purispatii sp. nov., isolated from a spacecraft assembly clean room.

In the course of studying the influence of N-fertilization on N(2) and N(2)O flux rates in relation to soil bacterial community composition of a long-term fertilization experiment in fen peat grassland, a strain group was isolated that was related to a strain isolated from a spacecraft assembly clean room during diversity studies of microorganisms, which withstood cleaning and bioburden reduction strategies. Both the fen soil isolates and the clean room strain revealed versatile physiological capacities in N-transformation processes by performing heterotrophic nitrification, respiratory ammonification and denitrification activity. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that the investigated isolates belonged to the genus Paenibacillus.

Reclassification of Leifsonia ginsengi (Qiu et al. 2007) as Herbiconiux ginsengi gen. nov., comb. nov. and description of Herbiconiux solani sp. nov., an actinobacterium associated with the phyllosphere of Solanum tuberosum L.

In the context of studying the effects of transgenic fructan-producing potatoes on the community structure of phyllosphere bacteria, a group of strains closely related to the species Leifsonia ginsengi was isolated. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the new isolates and L. ginsengi DSM 19088(T) formed a lineage at the genus level and this finding was supported by chemotaxonomic characterization.

Pseudomonas cedrina subsp. fulgida subsp. nov., a fluorescent bacterium isolated from the phyllosphere of grasses; emended description of Pseudomonas cedrina and description of Pseudomonas cedrina subsp. cedrina subsp. nov.

The taxonomic position of a group of four strains, isolated from the phyllosphere of grasses, within the species Pseudomonas cedrina was investigated. The isolates formed a separate cluster through ribotyping and MALDI-TOF MS, which could be clearly differentiated from the type strain of P. cedrina.

Agrococcus versicolor sp. nov., an actinobacterium associated with the phyllosphere of potato plants.

The taxonomic position of a group of actinobacterial strains isolated from the phyllosphere of potato plants was investigated by using a polyphasic approach. Although the similarity values for their 16S rRNA gene sequences suggested an intermediate position between Microbacterium and Agrococcus, the phylogenetic tree demonstrated a clear clustering of the representative strain, K 114/01(T), within the genus Agrococcus. The presence of 2,4-diaminobutyric acid as the diagnostic diamino acid in the cell-wall peptidoglycan of strain K 114/01(T) substantiated the affiliation to the genus Agrococcus.

Leucobacter tardus sp. nov., isolated from the phyllosphere of Solanum tuberosum L.

In the course of studying the composition of the microbial community in the phyllosphere of potato plants, a Gram-positive bacterium, strain K 70/01(T), was isolated. On the basis of 16S rRNA gene sequence analysis, it was shown that the investigated isolate represents a novel species in the genus Leucobacter; the closest phylogenetic neighbour was Leucobacter chromiireducens subsp. chromiireducens, with a sequence similarity of 96.

Effects of transgenic fructan-producing potatoes on the community structure of rhizosphere and phyllosphere bacteria.

The rhizosphere and phyllosphere microbial communities of transgenic potatoes producing fructan were studied in comparison with isogenic controls and conventional varieties in a field release experiment over a period of 3 years. Population densities and 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) analysis of the rhizosphere bacterial community only displayed the influence of annual and seasonal effects and the influence of field heterogeneity. In contrast, the T-RFLP analysis of the phyllosphere bacteria revealed in two of the 3 years significant differences in the community structure between the transgenic lines producing inulin and the other variants.

Chryseobacterium gregarium sp. nov., isolated from decaying plant material.

In this study, strain P 461/12T, isolated from decaying plant material after mulching a pasture, was shown to represent a novel species of the genus Chryseobacterium by means of a polyphasic approach. The closest phylogenetic neighbours to the novel strain, as determined by 16S rRNA gene sequence analysis, were Chryseobacterium daeguense K105T and Chryseobacterium soldanellicola PSD1-4T with gene sequence similarities of 97.4 % and 97.

Chryseobacterium luteum sp. nov., associated with the phyllosphere of grasses.

Three isolates obtained from grass samples were investigated by means of a polyphasic taxonomic study and were shown to represent a novel species within the genus Chryseobacterium. Comparison of 16S rRNA gene sequences and phenotypic features indicated that the three isolates belonged to a single species. On the basis of 16S rRNA gene sequence analysis, the closest phylogenetic neighbours were Chryseobacterium shigense and Chryseobacterium vrystaatense, which formed a stable cluster with the isolates; this phylogeny was supported by a high bootstrap value and was obtained using different treeing methods.

Pseudomonas lurida sp. nov., a fluorescent species associated with the phyllosphere of grasses.

The taxonomic position of a group of fluorescent pseudomonad strains isolated from the phyllosphere of grasses was investigated through a polyphasic approach. Riboprinting analysis revealed highly similar patterns for the investigated strains which supported, together with the agreement of many phenotypic characteristics, their affiliation to the same species. A comparison of 16S rRNA gene sequences of strain P 513/18(T), a representative strain from the grass isolates, revealed that it was affiliated to the cluster of the 'Pseudomonas fluorescens group', with Pseudomonas costantinii as the closest phylogenetic neighbour.