Surface wax in the ancestral grapevine Vitis sylvestris correlate with partial resistance to Powdery Mildew.

BACKGROUND: Powdery Mildew of Grapevine belongs to the major diseases in viticulture and requires intensive use of fungicides. Genetic introgression of resistance factors from wild grapes from North America and, recently, China, has been successful, but wine made from those varieties is still confronted with low consumer acceptance, due to differences in taste. RESULTS: The current work explores the potential of Vitis vinifera sylvestris, the wild ancestor of domesticated Grapevine, with respect to containing Erysiphe necator, the causative agent of Powdery Mildew. Making use of a germplasm collection comprising the entire genetic variability remaining in Germany, we show that there is considerable genetic variation in the formation of leaf surface waxes exceeding wax formation in commercial varieties. CONCLUSIONS: High wax formation correlates with reduced susceptibility to controlled infection with E. necator linked with perturbations of appressoria formation. We propose V. vinifera sylvestris as novel source for resistance breeding since it is genetically much closer to domesticated grapevine than the hitherto used sources from beyond the species barrier.

Rathayibacter rubneri sp. nov. isolated from Allium cepa var. Rijnsburger, an onion landrace.

The novel, aerobic, Gram-stain-positive, rod-shaped bacterial strain, ZW T2_19T, was isolated from an onion sample (Allium cepa var. Rijnsburger). Analyses of the 16S rRNA gene sequence revealed that ZW T2_19T represented a member of the genus Rathayibacter but may represent a novel species of this genus. Analyses of the whole draft genome sequences, i.e. digital DNA-DNA hybridisation (dDDH) and average nucleotide identity (ANI) of ZW T2_19T and all type strains of species of the genus Rathayibacter confirmed that ZW T2_19T represents a novel species of the genus Rathayibacter. The genome size of ZW T2_19T is 4.01 Mbp and the DNA G+C content is 71.8 mol%. Glucose, mannose, rhamnose and ribose were detected as whole-cell sugars of ZW T2_19T. The major respiratory quinone of ZW T2_19T is menaquinone MK-10, at 78.9 %. The detected peptidoglycan type in ZW T2_19T is a variant of type B2γ with {Gly} [l-diaminobutyric acid (l-DAB)/l-homoserine (l-Hse)] d-Glu-l-DAB. Polar lipids in ZW T2_19T consisted of one diphosphatidylglycerol, one phosphatidylglycerol, seven glycolipids, one phospholipid and one lipid. The fatty acid profile of ZW T2_19T predominantly consisted of anteiso-C15 : 0 (53 %), iso-C16 : 0 (21 %) and anteiso-C17 : 0 (18 %). In addition, API 20NE, API 50CH, API Coryne, API ZYM, antibiotic susceptibility, haemolysis and growth at different temperatures and with different supplements was investigated. On the basis of the results obtained using this polyphasic approach, including molecular, phenotypic and biochemical analyses, we propose the novel species Rathayibacter rubneri with the type and only strain ZW T2_19T (= DSM 114294T = LMG 32700T).

Characterisation of iron oxide-containing pearlescent pigments used as food colourants: nano-labelling required in the EU?

Pearlescent pigments are used as colourants to increase the attractiveness of food products, especially in the patisserie and confectionery sector. They can be seen as composite materials and consist of thin potassium aluminium silicate (E 555, mica) platelets as carrier material, coated with a thin metal oxide layer of TiO2 (E 171) and/or iron oxides (E 172). The European Food Safety Authority stated in 2020 that mica-based pearlescent pigments as a whole should be evaluated as new food additives. Obtaining dependable data for particle size and layer thickness of these pigments is crucial both for the demanded food additive evaluation itself and also for the nanomaterial labelling assessment of products containing these food colourants according to the 'Food Information to Consumers' regulation. Since it was found in a previous study on TiO2-containing pearlescent pigments (silver and golden coloured) that the coating consisted of nanoscaled constituent titanium oxide particles, in this follow-up study we investigated whether Fe2O3-containing pearlescent pigments exhibit a similar nanostructured morphology. For this purpose, five commercially-available food products containing these pigments were investigated. Static light scattering and flow particle image analysis were used as screening methods to determine the mica platelet size. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy was used for nanostructure analysis of the metal oxide coating. The carrier mica platelets were 34-96 µm in diameter and 300-800 nm thick. The coating thickness was found to be in the range of 75-105 nm, with the constituent round shaped iron oxide particles contained therein having a minimum Feret diameter of 37-64 nm.

An Attempt to Relate Oleogel Properties to Wax Ester Chemical Structures.

Wax esters are considered to have a dominant contribution in the gelling properties of wax-based oleogels. To understand their gelling behavior, oleogels of seven different wax esters (total carbon number from 30 to 46; c = 10% [m/m]) in medium-chain triglycerides oil were characterized. Scanning electron microscopy revealed that wax esters crystallize in rhombic platelets with a thickness of 80 to 115 monomolecular layers. Bright field microscopy showed that the regularity and face length of the crystals increased with the total carbon number and molecular symmetry of the respective wax ester. Oscillatory rheology was used to characterize the gel rigidity (Gmax*). Here, wax ester oleogels with smaller total carbon numbers yielded higher Gmax* values than those of wax esters with higher total carbon numbers. The gel rigidity (Gmax*) inversely correlated with the crystal face length. Smaller and optically less well-defined platelets promoted higher gel rigidities. In the case of the microstructure of a specific oleogel composition being manipulated by a variation in the cooling rates (0.8; 5; 10 K/min), this relationship persisted. The information compiled in this manuscript further elucidates the crystallization behavior of wax esters in oleogels. This contributes to the understanding of the composition-structure-functionality relationship of wax-based oleogels supporting future food applications.

Pseudomonas rustica sp. nov., isolated from bulk tank raw milk at a German dairy farm.

Here we present the description of a novel Pseudomonas species, designated Pseudomonas rustica sp. nov., which was isolated from raw milk samples obtained from Germany. Results of initial 16S rRNA gene sequence analysis assigned the strain into the genus Pseudomonas and showed Pseudomonas helmanticensis, Pseudomonas neuropathica and Pseudomonas atagonensis to be its closest relatives. Further studies including sequence analysis of the rpoB gene, multi-gene phylogenetic tree reconstruction, whole-genome sequence comparisons, cellular fatty acid analysis and chemotaxonomic characterization showed a clear separation from the known Pseudomonas species. Isolate MBT-4T was closely related to Pseudomonas helmanticensis, 'Pseudomonas crudilactis' and Pseudomonas neuropathica with average nucleotide identities based on blast values of 88.8, 88.8 and 88.6%, respectively. Therefore, the strain can be classified into the Pseudomonas koreensis subgroup of the Pseudomonas fluorescens group. The G+C content of strain MBT-4T was 58.9 mol%. The strain was catalase- and oxidase-positive, while the ß-galactosidase reaction was negative. Growth occurred between 4 and 30 °C and at pH values from pH 6.0 to 8.0. In conclusion, strain MBT-4T belongs to a novel species, for which the name Pseudomonas rustica sp. nov. is proposed. The type strain is MBT-4T (=DSM 112348T=LMG 32241T) and strain MBT-17 is also a representative of this species.

Determination of the Transport Efficiency in spICP-MS Analysis Using Conventional Sample Introduction Systems: An Interlaboratory Comparison Study.

In single particle inductively coupled plasma mass spectrometry (spICP-MS), the transport efficiency is fundamental for the correct determination of both particle number concentration and size. In the present study, transport efficiency was systematically determined on three different days with six carefully characterised gold nanoparticle (AuNP) suspensions and in seven European and US expert laboratories using different ICP-MS instruments and spICP-MS software. Both particle size-(TES)-and particle frequency-(TEF)-methods were applied. The resulting transport efficiencies did not deviate much under ideal conditions. The TEF method however systematically resulted in lower transport efficiencies. The extent of this difference (0-300% rel. difference) depended largely on the choice and storage conditions of the nanoparticle suspensions used for the determination. The TES method is recommended when the principal measurement objective is particle size. If the main aim of the measurement is the determination of the particle number concentration, the TEF approach could be preferred as it might better account for particle losses in the sample introduction system.

Adlercreutzia rubneri sp. nov., a resveratrol-metabolizing bacterium isolated from human faeces and emended description of the genus Adlercreutzia.

The novel, anaerobic, Gram-positive, rod-shaped bacterial strain, ResAG-91T, was isolated from a faecal sample of a male human volunteer. Analysis of the 16S rRNA gene sequence revealed that strain ResAG-91T showed high similarity to the type strains of Adlercreutzia equolifaciens subsp. equolifaciens and Adlercreutzia equolifaciens subsp. celatus. Analysis of the whole draft genome sequences, i.e. digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI), of strain ResAG-91T and the type strains of Adlercreutzia species revealed that strain ResAG-91T represents a novel species of the genus Adlercreutzia. The genome size of strain ResAG-91T is 2.8 Mbp and the G+C content is 63.3 mol%. The major respiratory quinone of strain ResAG-91T was MMK-5 (methylmenaquinone). Major cellular fatty acids were C15 : 0 anteiso, C14 : 0 iso and C14 : 0 2-OH. Galactose and ribose were detected as major whole cell sugars. Furthermore, the peptidoglycan type of strain ResAG-91T was A1γ with meso-diaminopimelic acid. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, one unidentified lipid, three unidentified phospholipids and five unidentified glycolipids. Strain ResAG-91T was able to metabolize the stilbene resveratrol into dihydroresveratrol. On the basis of this polyphasic approach, including phenotypical, molecular (16S rRNA gene and whole genome sequencing) and biochemical (fatty acids, quinones, polar lipids, peptidoglycan, whole cell sugars, Rapid ID32A and API20A) analyses, we propose the novel species Adlercreutzia rubneri sp. nov. with the type and only strain ResAG-91T (=DSM 111416T=JCM 34176T=LMG 31897T).

Characterisation of TiO2-containing pearlescent pigments with regard to the European Union labelling obligation of engineered nanomaterials in food.

A wide range of trendy food colourants and ready-to-eat foods containing pearlescent pigments providing glitter effects is currently on the market. These pearlescent pigments consist of mica (potassium aluminium silicate) platelets generally coated with titanium dioxide and/or iron oxides. All single components are approved food additives in the European Union (EU) (E 555, E 171 and E 172). However, the European Food Safety Authority (EFSA) has stated recently, that pearlescent pigments should be evaluated as new food additives. Food grade titanium dioxide was already shown to contain a considerable fraction of nanoparticles. Thus, the question about 'nano'-labelling of TiO2-containing pearlescent pigments according to the 'Novel Food' and 'Food Information to Consumers' regulations arose. In order to provide data for dealing with these issues, in this study four commercially available products of different food categories containing pearlescent pigments were characterised with focus on the structure, size and chemical composition of these pigments. The measurement methods used were flow particle image analysis (FPIA), static light scattering (SLS) and scanning electron microscopy (SEM) combined with energy-dispersive x-ray spectroscopy (EDX). After isolation from various food matrices, the glitter pigments could be easily identified and differentiated by fast FPIA screening from any remaining organic food matrix particles due to their typical platelet-like shape and transparency. The particle size distribution of the platelets was determined by means of SLS and found to be in the range of 8-167 µm. SEM was identified as the most suitable technique for the analysis of the nano-structured coating. For all constituent metal oxide particles (TiO2 and/or Fe2O3) a median minimum Feret diameter (Fmin) of 29.9-46.8 nm was obtained by quantitative SEM image analysis.

Intercellular communication is required for trap formation in the nematode-trapping fungus Duddingtonia flagrans.

Nematode-trapping fungi (NTF) are a large and diverse group of fungi, which may switch from a saprotrophic to a predatory lifestyle if nematodes are present. Different fungi have developed different trapping devices, ranging from adhesive cells to constricting rings. After trapping, fungal hyphae penetrate the worm, secrete lytic enzymes and form a hyphal network inside the body. We sequenced the genome of Duddingtonia flagrans, a biotechnologically important NTF used to control nematode populations in fields. The 36.64 Mb genome encodes 9,927 putative proteins, among which are more than 638 predicted secreted proteins. Most secreted proteins are lytic enzymes, but more than 200 were classified as small secreted proteins (< 300 amino acids). 117 putative effector proteins were predicted, suggesting interkingdom communication during the colonization. As a first step to analyze the function of such proteins or other phenomena at the molecular level, we developed a transformation system, established the fluorescent proteins GFP and mCherry, adapted an assay to monitor protein secretion, and established gene-deletion protocols using homologous recombination or CRISPR/Cas9. One putative virulence effector protein, PefB, was transcriptionally induced during the interaction. We show that the mature protein is able to be imported into nuclei in Caenorhabditis elegans cells. In addition, we studied trap formation and show that cell-to-cell communication is required for ring closure. The availability of the genome sequence and the establishment of many molecular tools will open new avenues to studying this biotechnologically relevant nematode-trapping fungus.

Rubneribacter badeniensis gen. nov., sp. nov. and Enteroscipio rubneri gen. nov., sp. nov., new members of the Eggerthellaceae isolated from human faeces.

Two novel, anaerobic, Gram-positive, rod-shaped bacterial strains, ResAG-85T and ResAG-96T, were isolated from a faecal sample of a male human. 16S rRNA gene sequences analyses indicated that these strains represent a distinct lineage within the family Eggerthellaceae. Strain ResAG-85T showed 92.3 % similarity to the type strains of the genera Eggerthella and Gordonibacter. Strain ResAG-96T clustered together with Paraeggerthella hongkongensis and the newly (but not validly) published genus 'Arabia massiliensis' (94.8 % similarity). Analysis of quinones revealed that MK-5 (21 % in ResAG-85T and 95 % in ResAG-96T) and MK-7 (53 % in strain ResAG-85T) were present, which were described for the first time for members of the Eggerthellaceae. Furthermore, MK-6 was present in both strains (25 % ResAG-85T and 5 % in ResAG-96T). The polar lipids detected in ResAG-85T and ResAG-96T consisted of eight and six glycolipids, respectively. Both strains possessed three phospholipids, one phosphatidylglycerol and one diphosphatidylglycerol. Analysis of fatty acids revealed that the percentage of total branched fatty acids was relatively high in comparison to related strains with 42 and 50 % of strains ResAG-85T and ResAG-96T but comparable to the value obtained for Gordonibacter pamelaeae DSM 19378T. On the basis of this polyphasic approach including molecular (16S rRNA gene sequencing) and biochemical methods (analysis of fatty acids, quinones, polar lipids, Rapid ID 32A and API 20A), the new genera and species Rubneribacter badeniensis with ResAG-85T (=DSM 105129T=JCM 32272T) and Enteroscipio rubneri with ResAG-96T (=DSM 105130T=JCM 32273T) as the type and only strains are described.