The strain was isolated from a crustacean shell (crab) which was collected on the 22nd May 2012 at low tide (8:30 a.m.) at 16°C ambient temperature in some residue water on the tidal mud flat of the German Wadden Sea, Neuharlingersiel (53°42′15.5″ N, 7°42′15.9″ E).

In a first step the surface of a crustacean shell was scraped-off and the shell material was transferred to sterile artificial sea water (ASW) supplemented with 10-fold diluted HD medium, to serve as biofilm suspension. ASW was prepared modified after Levring (1946) consisting of (per liter distilled water): 23.6 g NaCl; 0.64 g KCl; 4.53 g MgCl₂ · 6 H₂O; 5.94 g MgSO₄ · 7 H₂O; 1.3 g CaCl₂ · 2 H₂O; 10 mg Na₂PO4 · 2 H₂O; 2.1 mg NH₄NO₃. To avoid precipitation, the CaCl₂ solution was sterilized separately (Bruns et al., 2003). HD medium was composed of 0.25 g/l yeast extract, 0.1 g/l glucose, 0.5 g/l peptone and 2.38 g/l HEPES; the pH was adjusted to 7.3. The suspension of the bacterial biofilm was used to inoculate fifty 96 well plates employing a multidrop device as previously described (Jogler et al., 2013). Cultures were subsequently transferred to fresh 96 well plates with the same medium but supplemented with 2 mg/ml carbenicillin. Cultures that survived this treatment were screened employing a 16S rRNA gene targeting PCR, using the primer set 8f (5′–AGA GTT TGA TCM TGG CTC AG–3′) and 1492r (5′–GGY TAC CTT GTT ACG ACT T–3′) modified from Lane (1991). PCR amplifications were performed employing a Veriti 96-Well Thermal Cycler (Applied Biosystems) applying the following conditions: initial denaturation at 94°C for 5 min, followed by 10 cycles of denaturation at 94°C for 30 s, annealing at 59°C for 30 s and elongation at 72°C for 60 s. This first 10 cycles were followed by 20 cycles of denaturation at 94°C for 30 s, annealing at 54°C for 30 s, elongation at 72°C for 60 s and a final elongation at 72°C for 5 min. Amplification products were subject to 16S rRNA gene sequencing and NCBI database comparison to identify novel strains. Based on this analysis, strain NH11^T was selected for subsequent experiments. Further cultivation was performed employing a modified M2 culture broth (M2mod) previously used for Rhodopirellula baltica (Jeske et al., 2013) containing 0.5 g/l peptone, 0.25 g/l glucose, 250 ml/l artificial sea water (ASW), 5 ml/l vitamin solution (double concentrated) and 20 ml/l mineral salt solution. The medium was buffered with 2.38 g/l HEPES at pH 7.0. Artificial sea water was composed of 46.94 g/l NaCl, 7.84 g/l Na₂SO₄, 21.28 g/l MgCl₂ · 6 H₂O, 2.86 g/l CaCl₂ · 2 H₂O, 0.384 g/l NaHCO₃, 1.384 g/l KCl, 0.192 g/l KBr, 0.052 g/l H₃BO₃, 0.08 g/l SrCl₂ · 6 H₂O, and 0.006 g/l NaF. The vitamin solution was composed of 4 mg/l biotin, 4 mg/l folic acid, 20 mg/l pyridoxine-HCl, 10 mg/l riboflavin, 10 mg/l thiamine-HCl · 2 H₂O, 10 mg/l nicotinamide, 10 mg/l D-Ca-pentothenate, 0.2 mg/l vitamin B₁₂, and 10 mg/l p-aminobenzoic acid. Mineral salt solution was composed of 10 g/l nitrilotriacetic acid (NTA), 29.70 g/l MgSO₄ · 7 H₂O, 3.34 g/l CaCl₂ · 2 H₂O, 12.67 mg/l Na₂MoO₄ · 2 H₂O, 99 mg/l FeSO₄ · 7 H₂O, and 50 ml/l metal salt sol. “44”. Metal salt sol. “44” was composed of 250 mg/l Na-EDTA, 1.095 g/l ZnSO₄ · 7 H₂O, 0.5 g/l FeSO₄ · 7 H₂O, 154 mg/l MnSO₄ · H₂O, 39.20 mg/l CuSO₄ · 5 H₂O, 24.80 mg/l Co(NO₃)₂ · 6 H₂O, and 17.70 mg/l Na₂B₄O₇ · 10 H₂O. Solid medium was prepared by adding 15 g/l of three times prewashed agar (Becton, Dickinson and Company) to the medium.

Phase contrast (Phaco) and differential interference contrast (DIC) analysis were performed employing a Nikon Eclipse Ti inverted microscope with a Nikon N Plan Apochromat λ 100x/1.45 Oil objective and a Nikon DS-Ri2 camera. Specimens were immobilized in MatTek glass bottom dishes (35 mm, No. 1.5) employing a 1% agarose cushion. Images were analyzed using the Nikon NIS-Elements software (Version V4.3).

For field emission scanning electron microscopy (FESEM) bacteria were fixed in 1% formaldehyde in HEPES buffer (3 mM HEPES, 0.3 mM CaCl₂, 0.3 mM MgCl₂, 2.7 mM sucrose, pH 6.9) for 1 h on ice and washed one time employing the same buffer. Cover slips with a diameter of 12 mm were coated with a poly–L–lysine solution (Sigma–Aldrich) for 10 min, washed in distilled water and air–dried. Fifty microliter of the fixed bacteria solution was placed on a cover slip and allowed to settle for 10 min. Cover slips were then fixed in 1% glutaraldehyde in TE buffer (20 mM TRIS, 1 mM EDTA, pH 6.9) for 5 min at room temperature and subsequently washed twice with TE–buffer before dehydrating in a graded series of acetone (10, 30, 50, 70, 90, and 100%) on ice for 10 min at each concentration. Samples from the 100% acetone step were brought to room temperature before placing them in fresh 100% acetone. Samples were then subjected to critical–point drying with liquid CO₂ (CPD 300, Leica). Dried samples were covered with a gold/palladium (80/20) film by sputter coating (SCD 500, Bal–Tec) before examination in a field emission scanning electron microscope (Zeiss Merlin) using the Everhart Thornley HESE2–detector and the inlens SE–detector in a 25:75 ratio at an acceleration voltage of 5 kV. TEM micrographs of NH11^T cells were taken after negative staining with aqueous 0.1–2% uranyl acetate, employing a Zeiss transmission electron microscope EM 910 at an acceleration voltage of 80 kV at calibrated magnification as previously described (Wittmann et al., 2014). Prior TEM analysis cells were fixated for 2 h with 3% glutaraldehyde in 3 mM EM-HEPES buffer.

Thin sections of strain NH11^T were prepared by high pressure freezing and freeze substitution as previously described (Jogler et al., 2011). Sections were subsequently analyzed employing a JEOL 1200EX–80kV TEM microscope.

Physiological tests such as salinity, pH, and temperature tolerance were performed in liquid medium M2mod. To test the NaCl tolerance, medium M2mod was prepared employing ASW devoid of NaCl. The required NaCl concentrations were adjusted prior inoculation, using a 30% NaCl (w/v) solution. The ASW tolerance was tested using M2mod without ASW. Again, the required concentration of ASW was adjusted prior inoculation. Growth was detected by monitoring the optical density at 600 nm using a Photometer Ultrospec II (LKB Biochrom). Carbon source utilization was tested using the GN2 MicroPlate™ system (Biolog), while enzymatic activities were tested using the API® ZYM method (bioMérieux). The physical features of the cell wall were analyzed by Gram staining, KOH test and Bactident® Aminopeptidase test strips. Growth under anoxic conditions was investigated using the api® 20 NE system (bioMérieux) according to the manufacturer's instructions.

For phylogenetic analysis version 6.0.2 of the ARB software package (Ludwig et al., 2004) was used together with the SILVA database SSURef_NR99 (Version 119, released on 14.07.2014; Pruesse et al., 2007). The full length 16S rRNA gene sequence was imported into ARB and then aligned using the fast aligner tool of the ARB software package. The resulting alignment was further edited manually to improve alignment quality. During the phylogenetic tree reconstruction, different type strains of the phylum Planctomycetes were used as reference sequences, while type strains of the phylum Verrucomicrobia served as out-group. All sequences that were included are listed in Table S1. Tree reconstruction was performed with the ARB software package (Ludwig et al., 2004). The Maximum Likelihood RAxML module was used with the rate distribution model GTR GAMMA running the rapid bootstrap analysis algorithm. The Neighbor Joining tool was employed with Felsenstein correction, while the Maximum Parsimony analysis was achieved with the Phylip DNAPARS module. Bootstrap values for all three methods were calculated with 1000 resamplings including the E. coli 16S rRNA gene positions 101–1371.

To facilitate the taxonomic classification of strain NH11^T, a cluster analysis was performed employing version 6.0.6 of the ARB software package (Ludwig et al., 2004) together with the database SSURef_NR99 (Version 123.1, released on 03.03.16) using a 87.65% sequence identity cutoff (threshold for the minimal sequence identity within a taxonomic family after Yarza et al., 2014) and E. coli 16S rRNA gene positions 112–1393. This analysis included all sequences of the family Planctomycetaceae that were available in the database as well as sequences of uncultivated planctomycetes, while the three clusters obtained for Rubinisphaera brasiliensis DSM 5305^T, Gimesia maris 534-30^T and strain NH11^T were selected for further phylogenetic tree reconstruction. For the NH11^T containing cluster, the highest, lowest, average and median sequence identities were determined by calculating a distance matrix based on the E. coli 16S rRNA position 112–1393.

Genomic DNA of strain NH11^T was extracted using the Genomic-tip 20/G kit (Qiagen, Germany) and a >10 kb SMRTbell™ template library was prepared according to the manufacturer instructions (PacificBiosciences, USA). In brief, ~10 μg of genomic DNA was end-repaired and ligated to hairpin adapters overnight (DNA/Polymerase Binding Kit 2.0, Pacific Biosciences, USA). The SMRTbell™ template was exonuclease treated for removal of incompletely formed reaction products. Conditions for annealing of sequencing primers and binding of polymerase to purified SMRTbell™ template were assessed with the calculator in RS Remote (PacificBiosciences, USA). Five SMRT cells were sequenced on the PacBio RS/RSII (PacificBiosciences, USA), each covered with a 90-min movie. Eight additional SMRT cells were used applying the DNA/Polymerase Binding Kit P4 (PacificBiosciences, USA) in order to collect larger read lengths. For those cells, 180-min movies were taken and a sub read lengths up to 20 kb was observed.

In addition, 2 × 9,143,110 paired-end Illumina reads were obtained employing an Illumina HiSeq 2500 for 101 cycles in both directions using the TruSeq DNA Sample Prep Kit v2 according to the manufacturer's instructions (Illumina Inc., San Diego, CA, USA). The genome assembly was performed using the RS_HGAP_Assembly.2 protocol included in SMRT Portal version 2.2.0 utilizing 520,016 reads from all 13 SMRT cells applying standard parameters with exception of the genome size, which was set to 9,100,000. Thus, one final contig could be obtained, which afterwards was error-corrected using a subset of 2 × 4,000,000 Illumina reads using BWA (Li and Durbin, 2009) with subsequent variant and consensus calling employing the CLC Genomics Workbench 7.03 (http://www.clcbio.com). Visual inspection of 41 called variants has been performed using IGV (Thorvaldsdóttir et al., 2013) in addition to prediction of rRNAs using RNAmmer (Lagesen et al., 2007). Hereby, the error-corrected consensus was trimmed, circularized and adjusted to dnaA as the first gene. For the circular genome of Fuerstia marisgermanicae NH11^T the finishing quality is estimated to be at 99.9999% (QV 60) confirmed by final PacBio resequencing. Genome annotation has been performed using PROKKA 1.8 (Seemann, 2014).

Genomic islands and CRISPR regions were identified using IslandViewer3 (Dhillon et al., 2015) and CRT (Bland et al., 2007), respectively. The planctomycetal genomes for the gene content analysis were derived from NCBI and IMG (Markowitz et al., 2012) in April 2016 and had to match the following criteria upon CheckM analysis (Parks et al., 2015): completeness >90, contamination <5 and strain heterogeneity <20. Orthologs were detected with Proteinortho5 (Lechner et al., 2011), a tool that identifies the reciprocal best hits from the given protein sequences. The genome plot was then generated with BRIG (Alikhan et al., 2011). The G+C content of the DNA was estimated by analyzing the genome data using the software Artemis (Rutherford et al., 2000).

The gene size was calculated from annotations and analyzed with R (R Core Team, 2015) using the packages ggplot2 (Wickham, 2009), reshape (Wickham, 2007), xlsx (Dragulescu, 2014). Threshold for large genes were set to 5 kb according to Reva and Tümmler (2008). The biggest giant genes of NH11^T with a size over 20 kb were further analyzed using the InterProScan web service (Jones et al., 2014; Mitchell et al., 2015). The genome of strain NH11^T was screened for putative secondary metabolite clusters using the tool antiSMASH 3.0 (Weber et al., 2015).

Orthologs were identified using Proteinortho5 (Lechner et al., 2011) with the “-selfblast” option (which enables paralog-detection) enabled. Only genes present exclusively in single copy in all compared genomes were selected for MLSA. Alignments of the respective gene product amino acid sequences were generated individually for each ortholog group using MUSCLE v3.8.31 (Edgar, 2004a,b) and subsequently concatenated. Unalignable regions, caused by e.g., unique N-terminal or C-terminal sequence overhangs, were filtered from the concatenated alignment using Gblocks v.0.91b (Castresana, 2000). Phylogenetic relationships were inferred from the remaining unambiguous alignment positions by Neighbor Joining clustering with 1000 bootstrap iterations, using ARB 6.0.5 (Ludwig et al., 2004) and by Maximum Likelihood calculation using RAxML v. 8.0.26 (Stamatakis, 2014).

For fatty acid analysis, biomass of the three compared strains (NH11^T, R. brasiliensis DSM 5305^T and G. maris 534-30^T) was obtained from liquid cultures, grown in M2mod culture broth, at 20°C and slight agitation in baffled flasks. The obtained biomasses were processed according to the standards of the Identification Service of the German Collection of Microorganisms and Cell Cultures (DSMZ) (Miller, 1982; Kuykendall et al., 1988; Kämpfer and Kroppenstedt, 1996).

The accession numbers of the nucleotide sequences used for giant gene analysis or phylogenetic reconstruction are shown in Table S1. The NCBI genome accession number is CP017641.

Based on 16S rRNA gene phylogeny (Figure 1), strain NH11^T clusters together with G. maris within the family Planctomycetaceae (bootstrap support values: 69% for Maximum Likelihood, 43% for Maximum Parsimony, 46% for Neighbor Joining). However, it shares only 87.1% 16S rRNA gene sequence identity with G. maris based on BLAST analysis. Its next closest relative besides G. maris is R. brasiliensis (84.5% 16S rRNA gene sequence identity). An overview of the identities, generated with the manually curated SILVA alignment of all species of the phylum Planctomycetes, based on the 1270 base pairs used for phylogenetic reconstruction, is given in Table S2. In this analysis the Felsenstein correction was used, to take evolutionary events that occurred during speciation into account. According to this analysis strain NH11^T shares 85.4% identity with G. maris and 84.1% with R. brasiliensis, differing from BLAST search results described above. The performed cluster analysis revealed, that NH11^T, G. maris and R. brasiliensis form three distinct clusters within the family Planctomycetaceae with an identity of at least 87.65% within each cluster, which is identical with the minimum sequence identity threshold for taxonomic families (Yarza et al., 2014; Figures S1–S3). In particular, within the cluster of strain NH11^T the minimal sequence identity is 88.3% and the maximal identity is 99.9%. The average identity in this cluster is 94.48% with a median of 94.4%, matching the threshold of 92.25% for median sequence identity for taxonomic families.

Cells of strain NH11^T are pear to ovoid shaped (Figure 2) and form cream colored colonies on solid medium and motile swimmer cells in liquid culture. Cells are 1.2–2.5 × 0.9–1.7 μm in size. Its major phenotypic characteristics compared to those of G. maris and R. brasiliensis are listed in Table 1. No rosettes or stalks are formed in culture in contrast to the closest cultivated relatives G. maris and R. brasiliensis (Figures 2, 3). The surface of strain NH11^T is smooth and seems to lack crateriform structures except of polar regions were fiber-like structures seem to emerge from crateriform pits (Figure 3). Furthermore, the cell architecture of strain NH11^T and its mode of division seem to differ from all other planctomycetes described thus far (Figure 2). High pressure frozen and freeze substitution sections of strain NH11^T display a condensed nucleoid that was previously described in other planctomycetes, too (Figures 4A–C, white arrow). However, some cells display exceptional patterns of cytoplasmic invaginations (Figures 4A,B), while others, except for the condensed nucleoid, comprise a cell envelope comparable to E. coli (Figure 4C). Despite of the degree of invaginations with characteristics different from other planctomycetes, ribosomes seem to localize frequently in close proximity to the cytoplasmic membrane in a rope-of-pearls-like pattern (Figures 4A–C, white arrowheads). Cells of strain NH11^T divide through budding and unlike all other planctomycetes described thus far, the mother- and daughter-cells seem to be connected via a tubular structure during cell division (Figures 4D–F). In particular, a dark structure at the division plane seems to parallel the cell division ring previously described for anammox Planctomycetes (van Niftrik et al., 2009; Figure 4D, black arrow).

Strain NH11^T is able to grow between pH 6 and 10, with an optimal growth at pH 7 (Figure S4A). NH11^T tolerates up to 5% NaCl supplementation (Figure S4B) and requires at least 27.5% ASW for detectable growth (Figure S4C). In contrast, up to 230% ASW can be tolerated, while optimal growth conditions are in the range of 50–117.5% ASW. Temperature-wise, strain NH11^T can grow between 20 and 30°C, with optimal growth at 28°C (Figure S4D). Thus, strain NH11^T is a mesophilic organism. It is capable of utilizing a variety of carbon sources, listed in Table 2. In particular N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, L-arabinose, D-cellobiose, D-galactose, gentiobiose, α-D-glucose, α-D-lactose, lactulose, maltose, D-mannose, D-melibiose, β-methyl-D-glucoside, sucrose, D-trehalose, turanose, succinic acid mono-methyl-ester, acetic acid, γ-hydroxybutyric acid, itaconic acid, propionic acid and glycerol were utilized. In contrast to the closest related G. maris and R. brasiliensis, strain NH11^T was not able to use L-rhamnose as carbon source. The enzymatic repertoire of strain NH11^T comprises alkaline phosphatase, esterase, esterase lipase, leucinearylamidase, valinearylamidase, cysteine arylamidase, trypsin, α-chymotrypsin, acid phosphatase, naphthol-AS-BI-phosphohydrolase, α-galactosidase, and α-glucosidase. All enzymatic features are listed in Table 3. No growth under anoxic conditions was observed.

The fatty acids of strain NH11^T and its closest relatives G. maris and R. brasiliensis were analyzed and compared. The major fatty acids of strain NH11^T consist of 59.16% C_16:1 ω6c_/16:1 ω7c (summed feature 3), 19.83% C_18:1 ω6c/_18:1 ω7c (summed feature 8) and 15.12% C_16:0. In comparison, G. maris comprised 26.63% of C_16:1ω6c/_16:1 ω7c (summed feature 3), 23.50% of C_16:0, and 12.98% of C_16:0 10-methyl/Iso-C_17:1 ω6c (summed feature 9). The fatty acid profile of R. brasiliensis is composed of 47.10% C_16:0 and 45.77% C_16:1ω6c/_16:1 ω7c (summed feature 3). The complete fatty acid profiles of strain NH11^T, G. maris and R. brasiliensis are listed in Table 4.

Taken together, the general fatty acid profile of strain NH11^T is similar, yet distinct compared to its closest relatives G. maris and R. brasiliensis and differs mainly in the components proportions.

The complete chromosome of strain NH11^T comprises 8,920,478 bp, with a GC content of 55.9%. Within the genome, 6732 genes were annotated, of which 6645 were identified as protein-coding genes. As known for other planctomycetes (Fuerst and Sagulenko, 2011), only for 54.3% of these genes a function could be predicted, while the remaining genes were annotated as hypothetical proteins or proteins with unknown function. Notable islands of unique gene content were found to especially comprise regions of predicted genomic islands and regions containing so-called “giant genes” (Reva and Tümmler, 2008). The genomic features of strain NH11^T are summarized in Figure 5. In total, the genome of strain NH11^T comprises 45 giant genes, with a size greater than 5 kb (Figure S5). By the time of the first description of giant genes in the genome of R. baltica (Reva and Tümmler, 2008) no other planctomycetal genome sequence was available. Thus, we analyzed the general distribution of giant genes amongst Planctomycetes and found all 29 available planctomycetal genomes to encode such genes (Figure 6). Fifteen strains encoded genes with a size >20 kb, two of which Rhodopirellula sp. K833 and NH11^T, even encode five >20 kb genes (Figure S6). Thus, genes >20 kb could be found in less than 50% of the available planctomycetal genomes. Furthermore, genes >30 kb were exclusively found in strain NH11^T and G. maris. Thus strain NH11^T is somewhat unique if gene-length is compared to other planctomycetes. Consequently, we analyzed the potential function of five NH11^T protein-coding genes >20 kb. The results, obtained from the InterProScan web service, points toward potential functions in cell adhesion, carbohydrate binding and partial location on the outer membrane of NH11^T.

Because TEM analysis pointed toward an anammox Planctomycetes-like cell division ring (van Niftrik et al., 2009; Figure 4D, black arrow), the genome was analyzed toward the presence of the putative cell division ring protein of Candidatus “K. stuttgartiensis” (locus tag kustd1438, NCBI Accession Number CAJ72183). The best match was a hypothetical protein with 36% sequence identity but only 19% query coverage (Fuma_00096), suggesting that this is presumably not a homolog of the putative protein found in Candidatus “K. stuttgartiensis.” However, with a size of 8699 bp, the gene that encodes for this hypothetical protein of strain NH11^T belongs to the identified giant genes. Analysis of this hypothetical protein, using the InterProScan web service, revealed the presence of Lamin Tail- (IPR001322), Ig-like- (IPR032812), and PapD-like domains (IPR008962), indicating putative involvement of this protein in cell shape maintenance or sub cellular organization.

Besides the giant genes, further analysis of the genome revealed the presence of a complete CRISPR type II system (cas9: Fuma_04885, cas1: Fuma_4887, cas2: Fuma_4888; Taylor et al., 2015). Only 2 other of the 35 analyzed planctomycetal genomes, corresponding to organisms Blastopirellula marina SH 106 and Candidatus “Brocadia sinica JPN1,” comprise such a system while the closest relative of strain NH11^T, G. maris lacks equivalent genes. This indicates that bacteriophages can infect strain NH11^T as the CRISPR type II system is primarily used for phage defense. Furthermore, absence in G. maris indicates differences in terms of phage susceptibility and/ or defense strategy in comparison to strain NH11^T.

As Planctomycetes are a known source of potential bioactive compounds (Jeske et al., 2013), the genome of strain NH11^T was analyzed using antiSMASH 3.0 (Weber et al., 2015). In total, four secondary metabolite-associated gene clusters were found. In contrast, G. maris, as closest relative to NH11^T, encodes 9 putative secondary metabolite related genes and gene clusters. Thus, again, strain NH11^T differes from its peers.

However, the four identified genes and clusters might be related to bacteriocins (2), terpenes (1), and ectoines (1) based on the antiSMASH prediction. Ectoins are compatible solutes, playing a role in the salt stress response, e.g., in halophilic eubacteria (Peters et al., 1990; Bernard et al., 1993; Pastor et al., 2010). However, physiological tests gave no evidence for an increased salt tolerance [>5% NaCl (w/v)] of strain NH11^T (see Table 1).

The genome sequence of strain NH11^T was further used to verify the 16S rRNA gene sequence based phylogeny via Multi Locus Sequence Analysis (MLSA). This method enables to increase the phylogenetic resolution and to avoid the bias caused by single marker gene-based phylogenies. This was achieved by considering sequences of multiple independent single copy genes shared by the comparison organisms (Glaeser and Kämpfer, 2015). The MLSA-based phylogeny is shown in Figure 7 and further supports our 16S rRNA gene based placement.

Fuerstia (named in honor of John Fuerst, an Australian microbiologist from University of Queensland, who played a key role in planctomycetal research). The pear to ovoid shaped cells form aggregates in liquid culture, but no rosettes. Daughter cells are motile, while mother cells are non-motile and no stalk formation was observed. The surface is smooth, crateriform stuctures are limited to one pole and cells reproduce by polar budding while mother- and daughter cells are connected by a thin tubular-like structure. The lifestyle is heterotrophic, obligatory aerobic and mesophilic. The major fatty acids are C_16:1 ω6c/_16:1 ω7c (Summed feature), C_18:1ω6c/_18:1 ω7c (Summed feature), and C_16:0. Member of the phylum Planctomycetes, class Planctomycae, order Planctomycetales, family Planctomycetaceae. The type species is Fuerstia marisgermanicae.

Fuerstia marisgermanicae (ma′ris L. n. maris of the sea and ger.ma'ni.cae L. adj. German, pertaining to the German North Sea from which the type strain was isolated). In addition to the features described for the genus, the species exhibits the following properties. Colonies on solid medium are cream colored. Cells are 1.2–2.5 × 0.9–1.7 μm in size. Non motile mother cells spawn motile, swimming, daughter cells. Gram staining delivers no clear result. KOH test and aminopeptidase test are negative, while oxidase and catalase tests positive. The organism is able to degrade a wide range of carbon sources, in particular N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, L-arabinose, D-cellobiose, D-galactose, gentiobiose, α-D-glucose, α-D-lactose, lactulose, maltose, D-mannose, D-melibiose, β-methyl-D-glucoside, sucrose, D-trehalose, turanose, succinic acid mono-methyl-ester, acetic acid, γ-hydroxybutyric acid, itaconic acid, propionic acid, and glycerol were utilized. The enzymatic repertoire of the species, tested with API ZYM, is listed in Table 3. Growth occurs between pH 6 and 10 with an optimum at pH 7. At least 27.5% ASW is needed for growth, The optimal temperature for growth is 28°C (range between 20 and 30°C). The type strain is NH11^T (= DSM 27554 = LMG 27831) isolated from a crustacean shell.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.