A type III polyketide synthase cluster in the phylum Planctomycetota is involved in alkylresorcinol biosynthesis.

Members of the bacterial phylum Planctomycetota have recently emerged as promising and for the most part untapped sources of novel bioactive compounds. The characterization of more than 100 novel species in the last decade stimulated recent bioprospection studies that start to unveil the chemical repertoire of the phylum. In this study, we performed systematic bioinformatic analyses based on the genomes of all 131 described members of the current phylum focusing on the identification of type III polyketide synthase (PKS) genes. Type III PKSs are versatile enzymes involved in the biosynthesis of a wide array of structurally diverse natural products with potent biological activities. We identified 96 putative type III PKS genes of which 58 are encoded in an operon with genes encoding a putative oxidoreductase and a methyltransferase. Sequence similarities on protein level and the genetic organization of the operon point towards a functional link to the structurally related hierridins recently discovered in picocyanobacteria. The heterologous expression of planctomycetal type III PKS genes from strains belonging to different families in an engineered Corynebacterium glutamicum strain led to the biosynthesis of pentadecyl- and heptadecylresorcinols. Phenotypic assays performed with the heterologous producer strains and a constructed type III PKS gene deletion mutant suggest that the natural function of the identified compounds differs from that confirmed in other bacterial alkylresorcinol producers. KEY POINTS: • Planctomycetal type III polyketide synthases synthesize long-chain alkylresorcinols. • Phylogenetic analyses suggest an ecological link to picocyanobacterial hierridins. • Engineered C. glutamicum is suitable for an expression of planctomycete-derived genes.

Streptomyces marispadix sp. nov., isolated from marine beach sediment.

A novel actinomycetal strain, designated M600PL45_2T, was isolated from marine sediments obtained from Ingleses beach, Porto, on the Northern Coast of Portugal and was subjected to a polyphasic taxonomic characterisation study. The here described Gram-reaction-positive strain is characterised by the production of a brown pigment in both solid and liquid medium and forms typical helical hyphae that differentiate into smooth spores. The results of a phylogenetic analysis based on the 16S rRNA gene sequence indicated that M600PL45_2T has a high similarity to two members of the genus Streptomyces, Streptomyces bathyalis ASO4wetT (98.51 %) and Streptomyces daqingensis NEAU ZJC8T (98.44 %). The genome of M600PL45_2T has a size of 6 695 159 bp, a DNA G+C content of 70.71 mol% and 5538 coding sequences. M600PL45_2T grows at 15-37 °C and with a maximal growth rate between 25 °C and 30 °C. Growth at pH 6.0 to 9.0 with the optimal range between 6.0 and 7.5 was observed. M600PL45_2T showed a high salinity tolerance, growing with 0-10 % (w/v) NaCl, with best growth with 1-3% (w/v) NaCl. Major cellular fatty acids are iso-C15:0 (25.03 %), anteiso-C15:0 (17.70) and iso-C16:0 (26.90 %). The novel isolate was able to grow in media containing a variety of nitrogen and carbon sources. An antimicrobial activity screening indicated that an extract of M600PL45_2T has inhibitory activity against Staphylococcus aureus. On the basis of the polyphasic data, M600PL45_2T (= CECT 30365T = DSM 114036T) is introduced as the type strain of a novel species, that we named Streptomyces marispadix sp. nov.

Stratiformator vulcanicus gen. nov., sp. nov., a marine member of the family Planctomycetaceae isolated from a red biofilm in the Tyrrhenian Sea close to the volcanic island Panarea.

A novel planctomycetal strain, designated Pan189T, was isolated from biofilm material sampled close to Panarea Island in the Tyrrhenian Sea. Cells of strain Pan189T are round grain rice-shaped, form pink colonies and display typical planctomycetal characteristics including asymmetric cell division through polar budding and presence of crateriform structures. Cells bear a stalk opposite to the division pole and fimbriae cover the cell surface. Strain Pan189T has a mesophilic (optimum at 24 °C) and neutrophilic (optimum at pH 7.5) growth profile, is aerobic and heterotrophic. Under laboratory-scale cultivation conditions, it reached a generation time of 102 h (µmax = 0.0068 h-1), which places the strain among the slowest growing members of the phylum Planctomycetota characterized so far. The genome size of the strain is with 5.23 Mb at the lower limit among the family Planctomycetaceae (5.1-8.9 Mb). Phylogenetically, the strain represents a novel genus and species in the family Planctomycetaceae, order Planctomycetales, class Planctomycetia. We propose the name Stratiformator vulcanicus gen. nov., sp. nov. for the novel taxon, that is represented by the type strain Pan189T (= DSM 101711 T = CECT 30699 T).

Gemmata algarum, a Novel Planctomycete Isolated from an Algal Mat, Displays Antimicrobial Activity.

Axenic cultures of two strains, JC673T and JC717, both belonging to the phylum Planctomycetota, were isolated from distinct geographical locations in India. Strain JC673T was obtained from algal mats of a wetland situated in the state of Kerala, India, while strain JC717 originated from the Central Marine Fisheries Research Institute (CMFRI), state of Tamil Nadu, India. The two strains share 99.9% 16S rRNA gene sequence similarity and are most closely related to Gemmata obscuriglobus UQM 2246T (99.3% 16S rRNA gene sequence identity). The newly isolated strains are Gram-negative, grow aerobically and tolerate up to 4% (w/v) NaCl and a pH of up to 9.0. Cells are spherical and form pink-pigmented colonies. The respiratory quinone is MK-6. Major fatty acids are C18:0, C16:1ω5c and C16:0. Polar lipids include phosphatidylcholine, phosphatidylethanolamine, several unidentified amino lipids, unidentified phospholipids, additional unidentified lipids, and an unidentified choline lipid. The polyamine spermidine is produced by the two strains. The strains have a genome size of about 8.2 Mb with a DNA G+C content of 67.6%. Solvent-based culture extracts of the isolates showed antimicrobial activity against three bacterial test strains. Their phylogenetic position along with differences in morphological, physiological, and genomic features support the classification as a new species of the genus Gemmata, for which we propose the name Gemmata algarum sp. nov. Strain JC673T (=KCTC 72851T = NBRC 114340T) and JC717 are the type and non-type strain of the new species, respectively.

Mucisphaera calidilacus gen. nov., sp. nov., a novel planctomycete of the class Phycisphaerae isolated in the shallow sea hydrothermal system of the Lipari Islands.

For extending the current collection of axenic cultures of planctomycetes, we describe in this study the isolation and characterisation of strain Pan265T obtained from a red biofilm in the hydrothermal vent system close to the Lipari Islands in the Tyrrhenian Sea, north of Sicily, Italy. The strain forms light pink colonies on solid medium and grows as a viscous colloid in liquid culture, likely as the result of formation of a dense extracellular matrix observed during electron microscopy. Cells of the novel isolate are spherical, motile and divide by binary fission. Strain Pan265T is mesophilic (temperature optimum 30-33 °C), neutrophilic (pH optimum 7.0-8.0), aerobic and heterotrophic. The strain has a genome size of 3.49 Mb and a DNA G + C content of 63.9%. Phylogenetically, the strain belongs to the family Phycisphaeraceae, order Phycisphaerales, class Phycisphaerae. Our polyphasic analysis supports the delineation of strain Pan265T from the known genera in this family. Therefore, we conclude to assign strain Pan265T to a novel species within a novel genus, for which we propose the name Mucisphaera calidilacus gen. nov., sp. nov. The novel species is the type species of the novel genus and is represented by strain Pan265T (= DSM 100697T = CECT 30425T) as type strain.

Analysis of bacterial communities in a municipal duck pond during a phytoplankton bloom and isolation of Anatilimnocola aggregata gen. nov., sp. nov., Lacipirellula limnantheis sp. nov. and Urbifossiella limnaea gen. nov., sp. nov. belonging to the phylum Planctomycetes.

Waterbodies such as lakes and ponds are fragile environments affected by human influences. Suitable conditions can result in massive growth of phototrophs, commonly referred to as phytoplankton blooms. Such events benefit heterotrophic bacteria able to use compounds secreted by phototrophs or their biomass as major nutrient source. One example of such bacteria are Planctomycetes, which are abundant on the surfaces of marine macroscopic phototrophs; however, less data are available on their ecological roles in limnic environments. In this study, we followed a cultivation-independent deep sequencing approach to study the bacterial community composition during a cyanobacterial bloom event in a municipal duck pond. In addition to cyanobacteria, which caused the bloom event, members of the phylum Planctomycetes were significantly enriched in the cyanobacteria-attached fraction compared to the free-living fraction. Separate datasets based on isolated DNA and RNA point towards considerable differences in the abundance and activity of planctomycetal families, indicating different activity peaks of these families during the cyanobacterial bloom. Motivated by the finding that the sampling location harbours untapped bacterial diversity, we included a complementary cultivation-dependent approach and isolated and characterized three novel limnic strains belonging to the phylum Planctomycetes.

Metabolic and process engineering for microbial production of protocatechuate with Corynebacterium glutamicum.

3,4-Dihydroxybenzoate (protocatechuate, PCA) is a phenolic compound naturally found in edible vegetables and medicinal herbs. PCA is of high interest in the chemical industry and has wide potential for pharmaceutical applications. We designed and constructed a novel Corynebacterium glutamicum strain to enable the efficient utilization of d-xylose for microbial production of PCA. Shake flask cultivation of the engineered strain showed a maximum PCA titer of 62.1 ± 12.1 mM (9.6 ± 1.9 g L-1 ) from d-xylose as the primary carbon and energy source. The corresponding yield was 0.33 C-mol PCA per C-mol d-xylose, which corresponds to 38% of the maximum theoretical yield. Under growth-decoupled bioreactor conditions, a comparable PCA titer and a total amount of 16.5 ± 1.1 g PCA could be achieved when d-glucose and d-xylose were combined as orthogonal carbon substrates for biocatalyst provision and product synthesis, respectively. Downstream processing of PCA was realized via electrochemically induced crystallization by taking advantage of the pH-dependent properties of PCA. This resulted in a maximum final purity of 95.4%. The established PCA production process represents a highly sustainable approach, which will serve as a blueprint for the bio-based production of other hydroxybenzoic acids from alternative sugar feedstocks.

Identification and Microbial Production of the Raspberry Phenol Salidroside that Is Active against Huntington's Disease.

Edible berries are considered to be among nature's treasure chests as they contain a large number of (poly)phenols with potentially health-promoting properties. However, as berries contain complex (poly)phenol mixtures, it is challenging to associate any interesting pharmacological activity with a single compound. Thus, identification of pharmacologically interesting phenols requires systematic analyses of berry extracts. Here, raspberry (Rubus idaeus, var Prestige) extracts were systematically analyzed to identify bioactive compounds against pathological processes of neurodegenerative diseases. Berry extracts were tested on different Saccharomyces cerevisiae strains expressing disease proteins associated with Alzheimer's, Parkinson's, or Huntington's disease, or amyotrophic lateral sclerosis. After identifying bioactivity against Huntington's disease, the extract was fractionated and the obtained fractions were tested in the yeast model, which revealed that salidroside, a glycosylated phenol, displayed significant bioactivity. Subsequently, a metabolic route to salidroside was reconstructed in S cerevisiae and Corynebacterium glutamicum The best-performing S cerevisiae strain was capable of producing 2.1 mm (640 mg L-1) salidroside from Glc in shake flasks, whereas an engineered C glutamicum strain could efficiently convert the precursor tyrosol to salidroside, accumulating up to 32 mm (9,700 mg L-1) salidroside in bioreactor cultivations (yield: 0.81 mol mol-1). Targeted yeast assays verified that salidroside produced by both organisms has the same positive effects as salidroside of natural origin.

Tautonia plasticadhaerens sp. nov., a novel species in the family Isosphaeraceae isolated from an alga in a hydrothermal area of the Eolian Archipelago.

A novel planctomycetal strain, designated ElPT, was isolated from an alga in the shallow hydrothermal vent system close to Panarea Island in the Tyrrhenian Sea. Cells of strain ElPT are spherical, form pink colonies and display typical planctomycetal characteristics including division by budding and presence of crateriform structures. Strain ElPT has a mesophilic (optimum at 30 °C) and neutrophilic (optimum at pH 7.5) growth profile, is aerobic and heterotrophic. It reaches a generation time of 29 h (µmax = 0.024 h-1). The strain has a genome size of 9.40 Mb with a G + C content of 71.1% and harbours five plasmids, the highest number observed in the phylum Planctomycetes thus far. Phylogenetically, the strain represents a novel species of the recently described genus Tautonia in the family Isosphaeraceae. A characteristic feature of the strain is its tendency to attach strongly to a range of plastic surfaces. We thus propose the name Tautonia plasticadhaerens sp. nov. for the novel species, represented by the type strain ElPT (DSM 101012T = LMG 29141T).

Lignipirellula cremea gen. nov., sp. nov., a planctomycete isolated from wood particles in a brackish river estuary.

A novel planctomycetal strain, designated Pla85_3_4T, was isolated from the surface of wood incubated at the discharge of a wastewater treatment plant in the Warnow river near Rostock, Germany. Cells of the novel strain have a cell envelope architecture resembling that of Gram-negative bacteria, are round to pear-shaped (length: 2.2 ± 0.4 µm, width: 1.2 ± 0.3 µm), form aggregates and divide by polar budding. Colonies have a cream colour. Strain Pla85_3_4T grows at ranges of 10-30 °C (optimum 26 °C) and at pH 6.5-10.0 (optimum 7.5), and has a doubling time of 26 h. Phylogenetically, strain Pla85_3_4T (DSM 103796T = LMG 29741T) is concluded to represent a novel species of a novel genus within the family Pirellulaceae, for which we propose the name Lignipirellula cremea gen. nov., sp. nov.

Description of Polystyrenella longa gen. nov., sp. nov., isolated from polystyrene particles incubated in the Baltic Sea.

Planctomycetes occur in almost all aquatic ecosystems on earth. They have a remarkable cell biology, and members of the orders Planctomycetales and Pirellulales feature cell division by polar budding, perform a lifestyle switch from sessile to motile cells and have an enlarged periplasmic space. Here, we characterise a novel planctomycetal strain, Pla110T, isolated from the surface of polystyrene particles incubated in the Baltic Sea. After phylogenetic analysis, the strain could be placed in the family Planctomycetaceae. Strain Pla110T performs cell division by budding, has crateriform structures and grows in aggregates or rosettes. The strain is a chemoheterotroph, grows under mesophilic and neutrophilic conditions, and exhibited a doubling time of 21 h. Based on our phylogenetic and morphological characterisation, strain Pla110T (DSM 103387T = LMG 29693T) is concluded to represent a novel species belonging to a novel genus, for which we propose the name Polystyrenella longa gen. nov., sp. nov.

Caulifigura coniformis gen. nov., sp. nov., a novel member of the family Planctomycetaceae isolated from a red biofilm sampled in a hydrothermal area.

Pan44T, a novel strain belonging to the phylum Planctomycetes, was isolated from a red biofilm in a hydrothermal area close to the island Panarea in the Tyrrhenian Sea north of Sicily, Italy. The strain forms white colonies on solid medium and displays the following characteristics: cell division by budding, formation of rosettes, presence of matrix or fimbriae and long stalks. The cell surface has an interesting and characteristic texture made up of triangles and rectangles, which leads to a pine cone-like morphology of the strain. Strain Pan44T is mesophilic (temperature optimum 26 °C), slightly alkaliphilic (pH optimum 8.0), aerobic and heterotrophic. The strain has a genome size of 6.76 Mb with a G + C content of 63.2%. Phylogenetically, the strain is a member of the family Planctomycetaceae, order Planctomycetales, class Planctomycetia. Our analysis supports delineation of strain Pan44T from all known genera in this family, hence, we propose to assign it to a novel species within a novel genus, for which we propose the name Caulifigura coniformis gen. nov., sp. nov., represented by Pan44T (DSM 29405T = LMG 29788T) as the type strain.

Three novel Rubripirellula species isolated from plastic particles submerged in the Baltic Sea and the estuary of the river Warnow in northern Germany.

Planctomycetes are a unique and important phylum containing mostly aquatic bacteria, which are often associated with phototrophic surfaces. A complex lifestyle, their potential for the production of bioactive small molecules, their unusual cell biology and a large number of giant and hypothetical genes in their genomes make these microorganisms a fascinating topic for further research. Here, we characterise three novel planctomycetal strains isolated from polystyrene and polyethylene particles that were submerged in the German part of the Baltic Sea and the estuary of the river Warnow. All three strains showed typical planctomycetal traits such as division by polar budding and formation of rosettes. The isolated strains were mesophilic and neutrophilic chemoheterotrophs and reached generation times of 10-25 h during laboratory-scale cultivation. Taxonomically, the three strains belong to the genus Rubripirellula. Based on our analyses all three strains represent novel species, for which we propose the names Rubripirellula amarantea sp. nov., Rubripirellula tenax sp. nov. and Rubripirellula reticaptiva sp. nov. The here characterised strains Pla22T (DSM 102267T = LMG 29691T), Poly51T (DSM 103356T = VKM B-3438T) and Poly59T (DSM 103767T = LMG 29696T) are the respective type strains of these novel species. We also emend the description of the genus Rubripirellula.

Rubinisphaera italica sp. nov. isolated from a hydrothermal area in the Tyrrhenian Sea close to the volcanic island Panarea.

Planctomycetes is a fascinating phylum of mostly aquatic bacteria, not only due to the environmental importance in global carbon and nitrogen cycles, but also because of a unique cell biology. Their lifestyle and metabolic capabilities are not well explored, which motivated us to study the role of Planctomycetes in biofilms on marine biotic surfaces. Here, we describe the novel strain Pan54T which was isolated from algae in a hydrothermal area close to the volcanic island Panarea in the Tyrrhenian Sea, north of Sicily in Italy. The strain grew best at pH 9.0 and 26 °C and showed typical characteristics of planctomycetal bacteria, e.g. division by polar budding, formation of aggregates and presence of stalks and crateriform structures. Phylogenetically, the strain belongs to the genus Rubinisphaera. Our analysis suggests that Pan54T represents a novel species of this genus, for which we propose the name Rubinisphaera italica sp. nov. We suggest Pan54T (= DSM 29369 = LMG 29789) as the type strain of the novel species.

Stieleria varia sp. nov., isolated from wood particles in the Baltic Sea, constitutes a novel species in the family Pirellulaceae within the phylum Planctomycetes.

Species belonging to the bacterial phylum Planctomycetes are ubiquitous members of the microbial communities in aquatic environments and are frequently isolated from various biotic and abiotic surfaces in marine and limnic water bodies. Planctomycetes have large genomes of up to 12.4 Mb, follow complex lifestyles and display an uncommon cell biology; features which motivate the investigation of members of this phylum in greater detail. As a contribution to the current collection of axenic cultures of Planctomycetes, we here describe strain Pla52T isolated from wood particles in the Baltic Sea. Phylogenetic analysis places the strain in the family Pirellulaceae and suggests two species of the recently described genus Stieleria as current closest neighbours. Strain Pla52nT shows typical features of members of the class Planctomycetia, including division by polar budding and the presence of crateriform structures. Colonies of strain Pla52nT have a light orange colour, which is an unusual pigmentation compared to the majority of members in the phylum, which show either a pink to red pigmentation or entirely lack pigmentation. Optimal growth of strain Pla52nT at 33 °C and pH 7.5 indicates a mesophilic (i.e. with optimal growth between 20 and 45 °C) and neutrophilic growth profile. The strain is an aerobic heterotroph with motile daughter cells. Its genome has a size of 9.6 Mb and a G + C content of 56.0%. Polyphasic analyses justify delineation of the strain from described species within the genus Stieleria. Therefore, we conclude that strain Pla52nT = LMG 29463T = VKM B-3447T should be classified as the type strain of a novel species, for which we propose the name Stieleria varia sp. nov.

Additions to the genus Gimesia: description of Gimesia alba sp. nov., Gimesia algae sp. nov., Gimesia aquarii sp. nov., Gimesia aquatilis sp. nov., Gimesia fumaroli sp. nov. and Gimesia panareensis sp. nov., isolated from aquatic habitats of the Northern Hemisphere.

Thirteen novel planctomycetal strains were isolated from five different aquatic sampling locations. These comprise the hydrothermal vent system close to Panarea Island (Italy), a biofilm on the surface of kelp at Monterey Bay (CA, USA), sediment and algae on Mallorca Island (Spain) and Helgoland Island (Germany), as well as a seawater aquarium in Braunschweig, Germany. All strains were shown to belong to the genus Gimesia. Their genomes cover a size range from 7.22 to 8.29 Mb and have a G+C content between 45.1 and 53.7%. All strains are mesophilic (Topt 26-33 °C) with generation times between 12 and 32 h. Analysis of fatty acids yielded palmitic acid (16:0) and a fatty acid with the equivalent chain length of 15.817 as major compounds. While five of the novel strains belong to the already described species Gimesia maris and Gimesia chilikensis, the other strains belong to novel species, for which we propose the names Gimesia alba (type strain Pan241wT = DSM 100744T = LMG 31345T = CECT 9841T = VKM B-3430T), Gimesia algae (type strain Pan161T = CECT 30192T = STH00943T = LMG 29130T), Gimesia aquarii (type strain V144T = DSM 101710T = VKM B-3433T), Gimesia fumaroli (type strain Enr17T = DSM 100710T = VKM B-3429T) and Gimesia panareensis (type strain Enr10T = DSM 100416T = LMG 29082T). STH numbers refer to the Jena Microbial Resource Collection (JMRC).

Updates to the recently introduced family Lacipirellulaceae in the phylum Planctomycetes: isolation of strains belonging to the novel genera Aeoliella, Botrimarina, Pirellulimonas and Pseudobythopirellula and the novel species Bythopirellula polymerisocia and Posidoniimonas corsicana.

Eight novel strains of the phylum Planctomycetes were isolated from different aquatic habitats. Among these habitats were the hydrothermal vent system close to Panarea Island, a public beach at Mallorca Island, the shore of Costa Brava (Spain), and three sites with brackish water in the Baltic Sea. The genome sizes of the novel strains range from 4.33 to 6.29 Mb with DNA G+C contents between 52.8 and 66.7%. All strains are mesophilic (Topt 24-30 °C) and display generation times between 17 and 94 h. All eight isolates constitute novel species of either already described or novel genera within the family Lacipirellulaceae. Two of the novel species, Posidoniimonas polymericola (type strain Pla123aT = DSM 103020T = LMG 29466T) and Bythopirellula polymerisocia (type strain Pla144T = DSM 104841T = VKM B-3442T), belong to established genera, while the other strains represent the novel genera Aeoliella gen. nov., Botrimarina gen. nov., Pirellulimonas gen. nov. and Pseudobythopirellula gen. nov. Based on our polyphasic analysis, we propose the species Aeoliella mucimassa sp. nov. (type strain Pan181T = DSM 29370T = LMG 31346T = CECT 9840T = VKM B-3426T), Botrimarina colliarenosi sp. nov. (type strain Pla108T = DSM 103355T = LMG 29803T), Botrimarina hoheduenensis sp. nov. (type strain Pla111T = DSM 103485T = STH00945T, Jena Microbial Resource Collection JMRC), Botrimarina mediterranea sp. nov. (type strain Spa11T = DSM 100745T = LMG 31350T = CECT 9852T = VKM B-3431T), Pirellulimonas nuda sp. nov. (type strain Pla175T = DSM 109594T = CECT 9871T = VKM B-3448T) and Pseudobythopirellula maris sp. nov. (type strain Mal64T = DSM 100832T = LMG 29020T).

Calycomorphotria hydatis gen. nov., sp. nov., a novel species in the family Planctomycetaceae with conspicuous subcellular structures.

A novel strain belonging to the family Planctomycetaceae, designated V22T, was isolated from sediment of a seawater fish tank in Braunschweig, Germany. The isolate forms pink colonies on solid medium and displays common characteristics of planctomycetal strains, such as division by budding, formation of rosettes, a condensed nucleoid and presence of crateriform structures and fimbriae. Unusual invaginations of the cytoplasmic membrane and filamentous putative cytoskeletal elements were observed in thin sections analysed by transmission electron microscopy. Strain V22T is an aerobic heterotroph showing optimal growth at 30 °C and pH 8.5. During laboratory cultivations, strain V22T reached generation times of 10 h (maximal growth rate of 0.069 h-1). Its genome has a size of 5.2 Mb and a G + C content of 54.9%. Phylogenetically, the strain represents a novel genus and species in the family Planctomycetaceae, order Planctomycetales, class Planctomycetia. We propose the name Calycomorphotria hydatis gen. nov., sp. nov. for the novel taxon, represented by the type strain V22T (DSM 29767T = LMG 29080T).

Aureliella helgolandensis gen. nov., sp. nov., a novel Planctomycete isolated from a jellyfish at the shore of the island Helgoland.

A novel planctomycetal strain, designated Q31aT, was isolated from a jellyfish at the shore of the island Helgoland in the North Sea. The strain forms lucid white colonies on solid medium and displays typical characteristics of planctomycetal strains, such as division by budding, formation of rosettes, presence of crateriform structures, extracellular matrix or fibre and a holdfast structure. Q31aT is mesophilic (temperature optimum 27 °C), neutrophilic (pH optimum 7.5), aerobic and heterotrophic. A maximal growth rate of 0.017 h- 1 (generation time of 41 h) was observed. Q31aT has a genome size of 8.44 Mb and a G + C content of 55.3%. Phylogenetically, the strain represents a novel genus and species in the recently introduced family Pirellulaceae, order Pirellulales, class Planctomycetia. We propose the name Aureliella helgolandensis gen. nov., sp. nov. for the novel species, represented by Q31aT (= DSM 103537T = LMG 29700T) as the type strain.

Rosistilla oblonga gen. nov., sp. nov. and Rosistilla carotiformis sp. nov., isolated from biotic or abiotic surfaces in Northern Germany, Mallorca, Spain and California, USA.

Planctomycetes are ubiquitous bacteria with fascinating cell biological features. Strains available as axenic cultures in most cases have been isolated from aquatic environments and serve as a basis to study planctomycetal cell biology and interactions in further detail. As a contribution to the current collection of axenic cultures, here we characterise three closely related strains, Poly24T, CA51T and Mal33, which were isolated from the Baltic Sea, the Pacific Ocean and the Mediterranean Sea, respectively. The strains display cell biological features typical for related Planctomycetes, such as division by polar budding, presence of crateriform structures and formation of rosettes. Optimal growth was observed at temperatures of 30-33 °C and at pH 7.5, which led to maximal growth rates of 0.065-0.079 h-1, corresponding to generation times of 9-11 h. The genomes of the novel isolates have a size of 7.3-7.5 Mb and a G + C content of 57.7-58.2%. Phylogenetic analyses place the strains in the family Pirellulaceae and suggest that Roseimaritima ulvae and Roseimaritima sediminicola are the current closest relatives. Analysis of five different phylogenetic markers, however, supports the delineation of the strains from members of the genus Roseimaritima and other characterised genera in the family. Supported by morphological and physiological differences, we conclude that the strains belong to the novel genus Rosistilla gen. nov. and constitute two novel species, for which we propose the names Rosistilla carotiformis sp. nov. and Rosistilla oblonga sp. nov. (the type species). The two novel species are represented by the type strains Poly24T (= DSM 102938T = VKM B-3434T = LMG 31347T = CECT 9848T) and CA51T (= DSM 104080T = LMG 29702T), respectively.