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Strain JC669T was isolated from a floating island of Loktak lake, Manipur, India and shares the highest 16S rRNA gene sequence identity with Aquisphaera giovannonii OJF2T. The novel strain is aerobic, Gram negative, light pink-coloured, non-motile, NaCl intolerant and spherical to oval-shaped. It grows in the form of single cells or aggregates and possibly forms structures which appear like fruiting bodies. Strain JC669T grows well up to pH 9.0.The isolate produces MK-6 as respiratory quinone, C18:1ω9c, C16:0 and C18:0 as major fatty acids and phosphatidylcholine, an unidentified amino lipid, an unidentified choline lipid (UCL) and six additional unidentified lipids (UL1, 2, 3, 4, 5, 6) as polar lipids. Strain JC669T has a large genome size of 10.04 Mb and the genomic G + C content was 68.5 mol%. The genome contained all genes essential for lycopene related carotenoid biosynthesis. The polyphasic analysis of its phylogenetic position, morphological, physiological and genomic features supports the classification of strain JC669T as a novel species of the genus Aquisphaera, for which we propose the name Aquisphaera insulae sp. nov. Strain JC669T (= KCTC 72672T = NBRC 114306T) is the type strain of the novel species.

Planctomycetes of the family Pirellulaceae are commonly addressed as budding aquatic bacteria with a complex lifestyle. Although this family is well represented by cultured and taxonomically characterized isolates, nearly all of them were obtained from brackish or marine habitats. The examples of described freshwater Pirellulaceae planctomycetes are limited to two species only, Pirellula staley and 'Anatilimnocola aggregata'. In this study, we characterized a novel freshwater planctomycete of the genus 'Anatilimnocola', strain PX40

Agricultural productivity of pomegranate can be enhanced by identifying the crop-associated microbial diversity in the rhizosphere region with respect to plant growth promoters and other beneficial organisms. Traditional culture methods have limitations in microbial screening as only 1-2% of these organisms can be cultured. In the present study, 16S rRNA amplicon-based metagenomics approach using MinION Oxford Nanopore platform was employed to explore the microbial diversity in the rhizosphere of pomegranate Bhagwa variety, across variable soil depths from 0 to 5 cms (R2), 5-10 cms (R4) and 10-15 cms (R6), using bulk soil as the control. Across all the three layers, significant variations in pH, nitrogen content and total fungal count were observed. 16S rRNA analysis showed the abundance of planctomycetes, Pirellula staleyi, followed by bacteroidetes, Flavisolibacter LC59 and Niastella koreensis across the various soil depths in the rhizospheric soil samples. Pathway prediction analysis indicated arginine and proline metabolism (gamma-glutamyl putrescine oxidase) and hydrogen sulfide biosynthesis as the most abundant pathway hits. Comparative abundance analysis across layers showed the R6 layer with the maximum microbial diversity in terms of highest dimension of variation (79.2%) followed by R4 and R2 layers (p 0.01). Our analysis shows the significant influence of root zone in shaping microbial diversity. This study has reported the presence of Planctomycetes, Pirellula staleyi for the first time in the pomegranate field.

Heterologous endo-xanthanase (EX) from the thermophilic planktomycete Thermogutta terrifontis strain was obtained using Penicillium verruculosum 537 (ΔniaD) expression system with the cellobiohydrolase 1 gene promoter. Homogeneous EX with a molecular weight of 23.7 kDa (pI 6.5) was isolated using liquid chromatography methods. This xanthan degrading enzyme also possesses the enzymatic activity towards CM-cellulose, β-glucan, curdlan, lichenan, laminarin, galactomannan, xyloglucan but not towards p-nitrophenyl derivatives of β-D-glucose, mannose and cellobiose. The temperature and pH optima of EX were 55°C and 4.0, respectively; the enzyme exhibited 90% of its maximum activity in the temperature range 50-60°C and pH 3-5.

The discovery of new bioactive compounds is an invaluable aid to the development of new drugs. Strategies for finding novel molecules can focus on the exploitation of less studied organisms and ecosystems such as planctomycetes and brackish habitats. The unique cell biology of the underexplored Planctomycetota mean it is of particular interest. In this study, we aimed to isolate planctomycetes from the estuary of the Tejo river (Portugal). To reach this goal, macroalgae, water and sediments were sampled and diverse media and isolation techniques applied. Sixty-nine planctomycetal strains were brought into pure culture. An analysis of the 16S rRNA genes found that the majority of the isolates were affiliated to the genus Rhodopirellula. Putative novel taxa belonging to genera Stieleria and Rhodopirellula were also isolated and characterized morphologically. Enterobacterial repetitive intergenic consensus fingerprinting analyses showed higher diversity and different genotypes within close strains. Relevant biosynthetic gene clusters were found in most isolates and acetone extracts from representative strains exhibited mild antimicrobial activities against Escherichia coli and Staphylococcus aureus. Our work has not only enlarged the number and diversity of cultured planctomycetes but has also shown the potential for the discovery of bioactive compounds from the novel taxa.

Two pink-coloured, oxidase–catalase-positive, salt and alkali-tolerant planctomycetal strains (JC635T and JC645T) with pear to spherical-shaped, Gram-stain-negative, motile cells were isolated from Chilika lagoon, India. Both strains share highest 16S rRNA gene sequence identity with members of the genus Rhodopirellula (

A novel strain of Planctomycetes, designated JC670T, was isolated from a high altitude (~ 2900 m above sea level) soil sample collected from Garhwal region in the Western Himalaya. Colonies of this strain were observed to be light pink coloured with spherical to oval shaped cells having crateriform structures distributed all over the cell surface. The cells divide by budding. Strain JC670T was found to grow well at pH 7.0 and pH 8.0 and to tolerate up to 2% NaCl (w/v). MK6 was the only respiratory quinone identified. The major fatty acids of strain JC670T were identified as C18:1ω9c, C18:0 and C16:0, and phosphatidylcholine, two unidentified phospholipids and six unidentified lipids are present as the polar lipids. The polyamines putrescine and sym-homospermidine were detected. Strain JC670T shows high 16S rRNA gene sequence identity (95.4%) with Paludisphaera borealis PX4T. The draft genome size of strain JC670T is 7.97 Mb, with G + C content of 70.4 mol%. Based on phylogenetic analyses with the sequences of ninety-two core genes, low dDDH value (20.6%), low gANI (76.8%) and low AAI (69.1%) results, differential chemotaxonomic and physiological properties, strain JC670T (= KCTC 72850T = NBRC 114339T) is recognised as the type strain of a new species of the genus Paludisphaera, for which we propose the name Paludisphaera soli sp. nov.

Marine sponges harbor diverse microbiomes that contribute to their energetic and metabolic needs. Although numerous studies on sponge microbial diversity exist, relatively few focused on sponge microbial community changes under different sources of environmental stress. In this study, we assess the impact of elevated seawater temperature on the microbiome of cultured Lendenfeldia chondrodes, a coral reef sponge commonly found in marine aquaria. Lendenfeldia chondrodes exhibits high thermal tolerance showing no evidence of tissue damage or bleaching at 5 °C above control water temperature (26 °C). High-throughput sequencing of the bacterial 16S rRNA V4 region revealed a response of the microbiome of L. chondrodes to short-term exposure to elevated seawater temperature. Shifts in abundance and richness of the dominant bacterial phyla found in the microbiome of this species, namely Proteobacteria, Cyanobacteria, Planctomycetes, and Bacteroidetes, characterized this response. The observed resilience of L. chondrodes and the responsiveness of its microbiome to short-term increases in seawater temperature suggest that this holobiont may be capable of acclimating to anthropogenic-driven sublethal environmental stress via a re-accommodation of its associated bacterial community. This sheds a new light on the potential for resilience of some sponges to increasing surface seawater temperatures and associated projected regime shifts in coral reefs. Electronic supplementary material The online version of this article (10.1007/s00248-020-01556-z) contains supplementary material, which is available to authorized users.

Anaerobic ammonium oxidation (anammox) and denitrification are two different microbial reactions that form nitrogen gas. The initial step in the anammox reaction—reduction of nitrite to nitric oxide—is thought to be catalyzed by homologs of dissimilatory nitrite reductase, which is known to be involved in denitrification. Here, we reveal the crystal structure of the copper-containing nitrite reductase (CuNIR) of strain KSU-1, an anammox bacterium. CuNIR had a unique homohexameric structure with three disulfide bridges between homotrimers, although the trimer was similar to that of known CuNIRs. Kinetic and mutagenesis analyses suggested that the hexameric structure is important for the electron transfer reaction.

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).

In the wild various organisms contribute to daphnids diet. This study, intendeds to evaluate the potential of the concentration ofFeeding assays were performed according to standard guidelines for chronic assays (21 days), and life-history parameters and several biomarkers (protein content, oxidative stress, energetic reserves and pigments) were measured. Five food regimens were conducted with 20 individual replicates (A -The five diets showed a different C, N, and carotenoids composition, with an increase in the mixed diets. The results confirmed that the mixed diets improvedResults demonstrated that different diets provided a nutritional diversified food to the daphnids that induced differences in

A pink-coloured, salt- and alkali-tolerant planctomycetal strain (JC658

Climate change is altering the frequency and severity of drought events. Recent evidence indicates that drought may produce legacy effects on soil microbial communities. However, it is unclear whether precedent drought events lead to ecological memory formation, i.e., the capacity of past events to influence current ecosystem response trajectories. Here, we utilize a long-term field experiment in a mountain grassland in central Austria with an experimental layout comparing 10 years of recurrent drought events to a single drought event and ambient conditions. We show that recurrent droughts increase the dissimilarity of microbial communities compared to control and single drought events, and enhance soil multifunctionality during drought (calculated via measurements of potential enzymatic activities, soil nutrients, microbial biomass stoichiometry and belowground net primary productivity). Our results indicate that soil microbial community composition changes in concert with its functioning, with consequences for soil processes. The formation of ecological memory in soil under recurrent drought may enhance the resilience of ecosystem functioning against future drought events., Legacies of past ecological disturbances are expected but challenging to demonstrate. Here the authors report a 10-year field experiment in a mountain grassland that shows ecological memory of soil microbial community and functioning in response to recurrent drought.

Access to axenic cultures of Planctomycetes is crucial for further investigating their complex lifestyle, uncommon cell biology and primary and secondary metabolism. As a contribution to achieve this goal in the future, we here describe three strains belonging to the novel genus Novipirellula gen. nov. The strains were isolated from biotic and abiotic surfaces in the Baltic Sea and from the island Heligoland in the North Sea. Colony colours range from white to light pink. Cells are acorn-shaped and grew optimally at neutral pH and temperatures between 27 and 30 °C. Phylogenetic analyses revealed that the isolated strains represent three novel species belonging to a new genus, Novipirellula gen. nov. Beyond that, our analysis suggests that Rhodopirellula rosea LHWP3T, Rhodopirellula caenicola YM26-125T and Rhodopirellula maiorica SM1 are also members of this novel genus. Splitting the current genus Rhodopirellula into a more strictly defined genus Rhodopirellula and Novipirellula also allowed readjusting the genus threshold value for the gene rpoB, encoding the RNA polymerase β-subunit, which is used as phylogenetic marker for Planctomycetales. A threshold range of 75.5-78% identity of the analysed partial rpoB sequence turned out to be reliable for differentiation of genera within the family Planctomycetaceae.

Bacteria of the phylum Planctomycetes have a unique cell plan with an elaborate intracellular membrane system, thereby resembling eukaryotic cells. The origin and evolution of these remarkable features is debated. To study the evolutionary genomics of bacteria with complex cell architectures, we have resequenced the 9.2-Mb genome of the model organism Gemmata obscuriglobus and sequenced the 10-Mb genome of G. massiliana Soil9, the 7.9-Mb genome of CJuql4, and the 6.7-Mb genome of Tuwongella immobilis, all of which belong to the family Gemmataceae. A gene flux analysis of the Planctomycetes revealed a massive emergence of novel protein families at multiple nodes within the Gemmataceae. The expanded protein families have unique multidomain architectures composed of domains that are characteristic of prokaryotes, such as the sigma factor domain of extracytoplasmic sigma factors, and domains that have proliferated in eukaryotes, such as the WD40, leucine-rich repeat, tetratricopeptide repeat and Ser/Thr kinase domains. Proteins with identifiable domains in the Gemmataceae have longer lengths and linkers than proteins in most other bacteria, and the analyses suggest that these traits were ancestrally present in the Planctomycetales. A broad comparison of protein length distribution profiles revealed an overlap between the longest proteins in prokaryotes and the shortest proteins in eukaryotes. We conclude that the many similarities between proteins in the Planctomycetales and the eukaryotes are due to convergent evolution and that there is no strict boundary between prokaryotes and eukaryotes with regard to features such as gene paralogy, protein length, and protein domain composition patterns.

Ammonia-rich lagoon supernatant was treated using anammox process in an integrated fixed-film activated sludge (IFAS) laboratory reactor. Effective anammox activities were demonstrated over 259 days of operation. The ammonium removal efficiency reached 94% in Phase I with influent concentrations of NH4+, NO2− and chemical oxygen demand (COD) at 250 mg-N/L, 325 mg-N/L, and 145 mg-COD/L, and reached 88% in Phase II at 420 mg-N/L, 525 mg-N/L, and 305 mg-COD/L. When supplemented with nitritation effluent for nitrite sources in Phase III, the influent COD concentration increased to 583 mg-COD/L without loss of ammonia removal efficiency (87%). The specific anammox activity was higher in biofilm than in the suspended flocs (P

A novel aerobic bacterium, designated as strain GM2012T, was isolated from a microbial mat proliferating under the flow of thermal water dissipating from the wall of a 4000 m deep mine in South Africa. The cells were non-motile cocci, capable of budding, occurred in single or gathered in aggregates. The organism is a strictly aerobic chemoorganoheterotroph, preferring simple sugars and polysaccharides as growth substrates. The optimal growth occurred at 42 °C and pH 7.5–7.7. The predominant fatty acids were palmitate, stearate and oleate. The G+C content of the DNA was 70.1 mol%. The 16S rRNA gene sequence analysis placed strain GM2012T within the family Isosphaeraceae of the order Planctomycetales with 88–89 % sequence identity to Isosphaera pallida , Aquisphaera giovannonii, Singulisphaera acidiphila , Paludisphaera borealis and Tundrisphaera lichenicola type strains. Based on the genotypic and phenotypic distinctive features of the new strain, we propose a novel genus and species Tautonia sociabilis gen. nov., sp. nov. with the type strain GM2012T (=VKM B-2860,=KCTC 72013).

© The Author(s) 2019., Sterols and hopanoids are chemically and structurally related lipids mostly found in eukaryotic and bacterial cell membranes. Few bacterial species have been reported to produce sterols and this anomaly had originally been ascribed to lateral gene transfer (LGT) from eukaryotes. In addition, the functions of sterols in these bacteria are unknown and the functional overlap between sterols and hopanoids is still unclear. Gemmata obscuriglobus is a bacterium from the Planctomycetes phylum that synthesizes sterols, in contrast to its hopanoid-producing relatives. Here we show that sterols are essential for growth of G. obscuriglobus, and that sterol depletion leads to aberrant membrane structures and defects in budding cell division. This report of sterol essentiality in a prokaryotic species advances our understanding of sterol distribution and function, and provides a foundation to pursue fundamental questions in evolutionary cell biology., E.R.-M., C.S.-M., and D. P.D. were supported by BFU2013-40866-P and BFU-2016-7826-P. S.S., E.Y.G., M.H., F. B., and N.L.W. were supported by the US National Science Foundation awards MCB0920667 and IOS-1656637. S.S. and E.Y.G. were additionally supported by the US National Institutes of Health awards NCRR-P20RR016474 and NIGMS-P20GM103432. The acquisition of the GC-MS was made possible by the US National Science Foundation award CHE-0844694 to F.B.

Partial nitritation-anaerobic ammonium oxidation (PN-Anammox) was successfully applied for high-strength ammonium iron oxide red wastewater (IORW) treatment based on stable PN performance of zeolite-biological aerated filter (ZBAF). By separating Na2CO3 dosage avoid the high free ammonia (FA) inhibited nitritation, two-stage ZBAF was applied for achieving efficient PN with Na2CO3 as the alkalinity donor and saving about 40.0% of the alkalinity cost compared to NaHCO3. Moreover, Anammox was used for further nitrogen removal from IORW and stable total nitrogen (TN) removal was obtained at the influent NH 4 + -N concentration of 567 mg/L and TN removal efficiency kept above 70.0% after 100 days operation. High throughput sequencing-based approaches showed that Nitrosomoadaceae (AOB) and Kuenenia was dominance in two-stage ZBAF and Anammox samples respectively, while Nitrospire and Nitrobacter (NOB) undetected. The combined process should have advantages for similar high-strength ammonium wastewater treatment.

The daily use of the planctomycete Rhodopirellula rubra as an alternative or supplementary food source for Daphnia magna and its feasibility in the nutrition of transgenerational populations were studied. The life history parameters, fatty acids (saturated, mono- and polyunsaturated; SFAs, MUFAs and PUFAs), glycogen and protein contents of organisms during feeding assays and of the first generation were analysed. An increase in the yields of D. magna with the increase of the cell concentration of R. rubra was evident, but overall, bacteria supplied as the only food source was nutritionally insufficient as observed for all the parameters analysed. However, when R. rubra was added as supplement to the microalgae Raphidocelis subcapitata a significant improvement in the life history parameters was observed namely in the reproductive output and the somatic growth rate. The identified SFAs, MUFAs and PUFAs were the fatty acids more abundant in daphniids, and the feed regimens influenced daphniids fatty acid profiles. Additionally, the mixed diet resulted in a larger number and size of offspring in the different F1 broods as also observed with the results of F0 generation. The pink colouration present in D. magna body and eggs confirmed that bacteria were absorbed, the pigment(s) retained and passed on to the next generation. Our results showed that R. rubra can play an essential role in D. magna diet as a nutritional supplement showing potential biotechnological applications.

Nitric oxide (NO) has important functions in biology and atmospheric chemistry as a toxin, signaling molecule, ozone depleting agent and the precursor of the greenhouse gas nitrous oxide (N2O). Although NO is a potent oxidant, and was available on Earth earlier than oxygen, it is unclear whether NO can be used by microorganisms for growth. Anaerobic ammonium-oxidizing (anammox) bacteria couple nitrite reduction to ammonium oxidation with NO and hydrazine as intermediates, and produce N2 and nitrate. Here, we show that the anammox bacterium Kuenenia stuttgartiensis is able to grow in the absence of nitrite by coupling ammonium oxidation to NO reduction, and produce only N2. Under these growth conditions, the transcription of proteins necessary for NO generation is downregulated. Our work has potential implications in the control of N2O and NO emissions from natural and manmade ecosystems, where anammox bacteria contribute significantly to N2 release to the atmosphere. We hypothesize that microbial NO-dependent ammonium oxidation may have existed on early Earth., Anammox bacteria couple nitrite reduction to ammonium oxidation, with nitric oxide (NO) and hydrazine as intermediates, and produce N2 and nitrate. Here, Hu et al. show that an anammox bacterium can grow in the absence of nitrite by coupling ammonium oxidation to NO reduction, producing only N2.

Biofilm-based systems for shrimp aquaculture have emerged as a novel alternative to improve the water quality and obtain a better performance into ponds using zero or limited water exchange. The aims of this work were (1) to evaluate the production response and water quality of a super-intensive shrimp culture using a phototrophic biofilm as complementary food and (2) to study the bacterial diversity of these biofilms. A trial was performed, consisting of a shrimp culture system using biofilms as food source and a control without biofilms. Results showed that the biofilm-based system had better water quality and shrimp registered a higher growth performance compared to the control. Regarding the taxonomic profile of bacterial populations detected in the biofilm, results revealed that Proteobacteria, Bacteroidetes, and Planctomycetes were the three most abundant phyla; of these, eight bacterial orders belonging Rhizobiales, Clostridiales, Cytophagales, Actinomycetales, Vibrionales, Flavobacterales, Planctomycetales, Chlamydiales, and Rhodobacterales constituted a microbial core maintained over time. Some of these are related to anaerobic and aerobic removal processes of nitrogen. The results of this study are a first approach to understand how the bacterial communities forming biofilms are related to water quality of ponds and production performance of aquaculture farms, and how the microbial succession may cause changes on the taxonomic profile biofilms.

The feasibility of implementing anaerobic ammonium oxidation (anammox) granules to start up high-loading anaerobic sulfide oxidation (ASO) in an upflow anaerobic sludge bed (UASB) reactor was investigated. An innovation method of the reverse start-up of anammox was also validated. Firstly, the reactor was operated to treat sulfide-rich wastewaters into which nitrite was introduced as an electron acceptor. An high-rate performance with sulfide and nitrate removal rates of 105.5 ± 0.11 kg S m−3 d−1 and 28.45 ± 3.40 kg N m−3 d−1, respectively, was accomplished. Sulfurovum were enriched with the increase of the substrate load and then conquered Candidatus Kuenenia to be the predominant bacteria. Excitation-emission matrix (EEM) spectroscopy showed that the intensities of fluorescence decreased and protein-like substrates were the main components associated with the process of start-up. FT-IR analysis found that the main functional groups indicator were O-H groups. Secondly, the reverse start-up of anammox (achieving 90% TN removal) was achieved immediately when the substrate changed. 16S rRNA analysis indicated the successfully enrichment of anammox bacteria (Candidatus Kuenenia). These results suggest that anammox granules can act as inoculum of high-loading ASO process and the reverse start-up provides a new perspective for the fast initiation of anammox process.

Planctomycetes of the family Gemmataceae are strictly aerobic chemo-organotrophs that display a number of hydrolytic capabilities. A member of this family, Telmatocola sphagniphila SP2

Cysteine Synthase (CS), the enzyme that synthesizes cysteine, performs non-canonical regulatory roles by binding and modulating functions of disparate proteins. Beyond its role in catalysis and regulation in the cysteine biosynthesis pathway, it exerts its moonlighting effect by binding to few other proteins which possess a C-terminal “CS-binding motif”, ending with a terminal ILE. Therefore, we hypothesized that CS might regulate many other disparate proteins with the “CS-binding motif”. In this study, we developed an iterative sequence matching method for mapping moonlighting biochemistry of CS and validated our prediction by analytical and structural approaches. Using a minimal protein-peptide interaction system, we show that five previously unknown CS-binder proteins that participate in diverse metabolic processes interact with CS in a species-specific manner. Furthermore, results show that signatures of protein–protein interactions, including thermodynamic, competitive-inhibition, and structural features, highly match the known CS-Binder, serine acetyltransferase (SAT). Together, the results presented in this study allow us to map the extreme multifunctional space (EMS) of CS and reveal the biochemistry of moonlighting space, a subset of EMS. We believe that the integrated computational and experimental workflow developed here could be further modified and extended to study protein-specific moonlighting properties of multifunctional proteins.

The hydroxylamine oxidoreductase (HAO) family consists of octaheme proteins that harbor seven bis-His ligated electron-transferring hemes and one 5-coordinate catalytic heme with His axial ligation. Oxidative HAOs have a homotrimeric configuration with the monomers covalently attached to each other via a unique double cross-link between a Tyr residue and the catalytic heme moiety of an adjacent subunit. This cross-linked active site heme, termed the P460 cofactor, has been hypothesized to modulate enzyme reactivity toward oxidative catalysis. Conversely, the absence of this cross-link is predicted to favor reductive catalysis. However, this prediction has not been directly tested. In this study, an HAO homolog that lacks the heme-Tyr cross-link (HAOr) was purified to homogeneity from the nitrite-dependent anaerobic ammonium-oxidizing (anammox) bacterium Kuenenia stuttgartiensis, and its catalytic and spectroscopic properties were assessed. We show that HAOr reduced nitrite to nitric oxide and also reduced nitric oxide and hydroxylamine as nonphysiological substrates. In contrast, HAOr was not able to oxidize hydroxylamine or hydrazine supporting the notion that cross-link-deficient HAO enzymes are reductases. Compared with oxidative HAOs, we found that HAOr harbors an active site heme with a higher (at least 80 mV) midpoint potential and a much lower degree of porphyrin ruffling. Based on the physiology of anammox bacteria and our results, we propose that HAOr reduces nitrite to nitric oxide in vivo, providing anammox bacteria with NO, which they use to activate ammonium in the absence of oxygen.

Organophosphorous nerve agents (OPNA) pose an actual and major threat for both military and civilians alike, as an upsurge in their use has been observed in the recent years. Currently available treatments mitigate the effect of the nerve agents, and could be vastly improved by means of scavengers of the nerve agents. Consequently, efforts have been made over the years into investigating enzymes, also known as bioscavengers, which have the potential either to trap or hydrolyze these toxic compounds. We investigated the previously described esterase 2 from Thermogutta terrifontis (TtEst2) as a potential bioscavenger of nerve agents. As such, we assessed its potential against G-agents (tabun, sarin, and cyclosarin), VX, as well as the pesticide paraoxon. We report that TtEst2 is a good bioscavenger of paraoxon and G-agents, but is rather slow at scavenging VX. X-ray crystallography studies showed that TtEst2 forms an irreversible complex with the aforementioned agents, and allowed the identification of amino-acids, whose mutagenesis could lead to better scavenging properties for VX. In conjunction with its cheap production and purification processes, as well as a robust structural backbone, further engineering of TtEst2 could lead to a stopgap bioscavenger useful for in corpo scavenging or skin decontamination.

The profiles of total fatty acids (TFAs) and the neutral lipid fatty acids (NLFAs) were compared for the bacterium Rhodopirellula rubra and the alga Raphidocelis subcapitata (conventional food source for Daphnia magna). D. magna NLFAs were assessed when this crustacean was fed with bacterium and alga, individually or in combination. After NLFA extraction, the profiles of the various organisms were characterized by gas chromatography. Results evidenced the relevance of the different composition of the fatty acid (FAs) fractions in the different organisms, R. rubra and R. subcapitata. In these species, the NFLA analyses revealed high amounts of long chain FAs (C

Planctomycetes are very intriguing bacteria that impassion, inspire and stimulate the scholars that study them. Discovered in the beginning of the last century, they were initially confused with 'floating fungus', hence the genus name Planctomyces (planktos, wandering, floating; Gr. masc. n. mukês, fungus; https://lpsn.dsmz.de/genus/planctomyces). However, it was only in the second half of the twentieth century that their diversity started to be unveiled (Devos and Ward 2014; Lage et al. 2019; Dedysh et al. 2020a). Together with Chlamydiae, Verrucomicrobia and other poorly described phyla, such as Lentisphaerae, Kiritimatiellaeota and other candidate phyla, they form the Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) superphylum (Wagner and Horn 2006). Planctomycetes are distinctive bacteria and their divergent characteristics have confused both those scientists analysing them and also those considering them as interesting curiosities (Wiegand et al. 2018; Rivas-Marín and Devos 2018). For example, they have been mistakenly proposed to form a third cell type organisation, neither Gram-negative nor Gram-positive (Santarella-Mellwig et al. 2013; Devos 2014a, b; Boedeker et al. 2017). Indeed, they have even been called the 'nucleated' bacteria (Fuerst 2005). For a long time, they were thought to lack peptidoglycan, an anomaly considered as shared with the Chlamydiae but recently reappraised (Jeske et al. 2015; van Teeseling et al. 2015). These and other misconceptions have pervaded the PVC field for a long time. With the advances in genomics, molecular and microscopy techniques, combined with more sampling, Planctomycetes researchers have begun to fix some of the most obvious misconceptions in the field (reviewed in Devos 2014a, b; Wiegand et al. 2018; Rivas-Marín and Devos 2018; Lage et al. 2019). However, two of the real divergent features of Planctomycetes, also shared with Chlamydiae, are their asymmetrical division and their lack of the division protein FtsZ, unique in the free-living bacterial world (Rivas-Marín et al. 2016, 2020).

Planctomycetes are bacteria found in several environments, such as mangroves. In the coastline of the State of Sao Paulo (Brazilian Southeast), mangroves occur in different stages of environmental contamination, promoted by the proximity to the city and industrial activities. One of these mangroves (located in the city of Bertioga) is characterized by the high impact due to past petroleum and ongoing urban contamination. We isolated five bacteria affiliated to Planctomycetes from this mangrove and further subjected them to phenotypical and genetic analysis. The tolerance for salinity was demonstrated by the cultivation under distinct concentrations of NaCl. The ability of this bacterium to use diverse carbon sources was revealed by the use of 30 C-sources from a total of 31 tests. We found the isolate Rhodopirellula sp. MGV very closely affiliated to species of the genus Rhodopirellula, harboring a genome with 7.16 Mbp and 55.3% of GC. The annotation of the 77 contigs resulted in 6.284 CDS, with a remarkable occurrence of sequences associated with aromatic carbon metabolism. In conclusion, we present the isolation and characterization of a Planctomycetes from mangroves, suggesting its participation in the degradation of hydrocarbons present in the contaminated mangroves studied.

Bacteria of the Planctomycetes phylum have many unique cellular features, such as extensive membrane invaginations and the ability to import macromolecules. These features raise intriguing questions about the composition of their cell envelopes. In this study, we have used microscopy, phylogenomics, and proteomics to examine the composition and evolution of cell envelope proteins in Tuwongella immobilis and other members of the Planctomycetes. Cryo-electron tomography data indicated a distance of 45 nm between the inner and outer membranes in T. immobilis. Consistent with the wide periplasmic space, our bioinformatics studies showed that the periplasmic segments of outer-membrane proteins in type II secretion systems are extended in bacteria of the order Planctomycetales. Homologs of two highly abundant cysteine-rich cell wall proteins in T. immobilis were identified in all members of the Planctomycetales, whereas genes for peptidoglycan biosynthesis and cell elongation have been lost in many members of this bacterial group. The cell wall proteins contain multiple copies of the YTV motif, which is the only domain that is conserved and unique to the Planctomycetales. Earlier diverging taxa in the Planctomycetes phylum contain genes for peptidoglycan biosynthesis but no homologs to the YTV cell wall proteins. The major remodeling of the cell envelope in the ancestor of the Planctomycetales coincided with the emergence of budding and other unique cellular phenotypes. The results have implications for hypotheses about the process whereby complex cellular features evolve in bacteria.

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.

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.

The fjords of west Spitsbergen Svalbard, Arctic Norway, are undergoing a transformation as the impact of nutrient rich warmer Atlantic water is significantly altering the primary production and subsequently the carbon pool. Members of the phylum Planctomycetes are ubiquitous in marine systems and are important in the mineralization of organic matter. Hence, the phylogenetic diversity and distribution pattern of Planctomycetes in the surface sediments of a high Arctic fjord, the Kongsfjorden were studied. Further, considering the release of ammonium as a part of mineralization, the diversity of bacterial community involved in anaerobic ammonium oxidation (anammox) was also evaluated. The highly diverse Planctomycetes community, which consisted mainly of uncultivated and uncharacterized Planctomycetes, was observed in the study area with a total of 162 OTUs. The major genera observed were Blastopirellula (13.3%), Gimesia (13%), Rhodopirellula (10%), Planctomicrobium (2%) and Thermogutta (1.6%). Functional prediction revealed the dominance of carbohydrate metabolism genes and the presence of gene clusters for production of secondary metabolites and xenobiotic degradation. Anammox bacterial sequences were detected from all the samples with a total of 52 OTUs. Most of the OTUs belonged to the genus Candidatus Scalindua and three distinct clusters were observed in the phylogenetic tree, (a) Ca. Scalindua brodae (49%), (b) Ca. Scalindua wagneri (31%) and (c) Ca. Scalindua marina (12%) based on their phylogenic distance. Our findings suggest the existence of highly diverse Planctomycetes and anammox bacterial community with regional variants in the sediments of Kongsfjorden.

Planctomycetes is a ubiquitous phylum of mostly aquatic bacteria that have a complex lifestyle and an unusual cell biology. Here, we describe three strains of the same novel genus and species isolated from three different environments; from a red biofilm at a hydrothermal vent in the Mediterranean Sea, from sediment in a salt-water fish tank, and from the surface of algae at the coast of the Balearic island Mallorca. The three strains Mal65T (DSM 100706T = LMG 29792T, Pan14r (DSM 29351 = LMG 29012), and V7 (DSM 29812 = CECT 9853 = VKM B-3427) show typical characteristics of the Planctomycetaceae family, such as cell division by budding, crateriform structures and growth in aggregates or rosettes. The strains are mesophilic, neutrophilic to alkaliphilic as well as chemoheterotrophic and exhibit doubling times between 12 and 35 h. Based on our phylogenetic analysis, the three strains represent a single novel species of a new genus, for which we propose the name Crateriforma conspicua gen. nov. sp. nov.

Most bacteria divide by binary fission using an FtsZ-based mechanism that relies on a multi-protein complex, the divisome. In the majority of non-spherical bacteria another multi-protein complex, the elongasome, is also required for the maintenance of cell shape. Components of these multi-protein assemblies are conserved and essential in most bacteria. Here, we provide evidence that at least three proteins of these two complexes are not essential in the FtsZ-less ovoid planctomycete bacterium Planctopirus limnophila which divides by budding. We attempted to construct P. limnophila knock-out mutants of the genes coding for the divisome proteins FtsI, FtsK, FtsW and the elongasome protein MreB. Surprisingly, ftsI, ftsW and mreB could be deleted without affecting the growth rate. On the other hand, the conserved ftsK appeared to be essential in this bacterium. In conclusion, the canonical bacterial cell division machinery is not essential in P. limnophila and this bacterium divides via budding using an unknown mechanism., This work was supported by BFU2016-78326-P and MDM-2016-0687, Spanish Ministerio de Economía y Competitividad. Also, part of this work was supported by a visiting scientist grant awarded to ERM by the Soehngen Institute of Anaerobic Microbiology (SIAM, project 024002002) of the Netherlands Organisation for Scientific Research (NWO). SHP is supported by the NWO grant ALWOP.308 and LC by the Spinoza prize awarded to Prof. dr. M.S.M. Jetten.

Pirellula-like planctomycetes are ubiquitous aquatic bacteria, which are often detected in anoxic or micro-oxic habitats. By contrast, the taxonomically described representatives of these bacteria, with very few exceptions, are strict aerobes. Here, we report the isolation and characterization of the facultatively anaerobic planctomycete, strain PX69T, which was isolated from a boreal lake. Its 16S rRNA gene sequence is affiliated with the Pirellula-related Pir4 clade, which is dominated by environmental sequences retrieved from a variety of low-oxygen habitats. Strain PX69T was represented by ellipsoidal cells that multiplied by budding and grew on sugars, some polysaccharides and glycerol. Anaerobic growth occurred by means of fermentation. Strain PX69T grew at pH 5.5–7.5 and at temperatures between 10 and 30 °C. The major fatty acids were C18:1ω9c, C16:0 and C16:1ω7c; the major intact polar lipid was dimethylphosphatidylethanolamine. The complete genome of strain PX69T was 6.92 Mb in size; DNA G + C content was 61.7 mol%. Among characterized planctomycetes, the highest 16S rRNA gene similarity (90.4%) was observed with ‘Bythopirellula goksoyri’ Pr1d, a planctomycete from deep-sea sediments. We propose to classify PX69T as a novel genus and species, Lacipirellula parvula gen. nov., sp. nov.; the type strain is strain PX69T (=KCTC 72398T = CECT 9826T = VKM B-3335T). This genus is placed in a novel family, Lacipirellulaceae fam. nov., which belongs to the order Pirellulales ord. nov. Based on the results of comparative genome analysis, we also suggest establishment of the orders Gemmatales ord. nov. and Isosphaerales ord. nov. as well as an emendation of the order Planctomycetales.

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.

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).

Planctomycetes are part of the PVC superphylum together with Verrucomicrobia, Chlamydiae and others. They are budding bacteria with very distinctive characteristics, such as a remarkable morphology and cell biology. Planctomycetes can be found in almost all habitats, and seem to have a preference for marine biotic and abiotic surfaces, on which they frequently occur in biofilm-forming communities. To extend the number of axenic cultures of planctomycetal strains, we isolated Pan97T from a biofilm in a volcanic site close to the Italian island Panarea in the Thyrrhenian Sea. The physiology, genome and morphology of the novel strain were characterised revealing typical planctomycetal characteristics, such as, division by polar budding and presence of crateriform structures. The strain shows pear-shaped cells of 1.5 ± 0.3 µm × 0.8 ± 0.2 µm and forms white- to cream-coloured colonies on solid medium. Strain Pan97T is mesophilic and neutrophilic, since growth was observed at a pH range of 5.5–9.5 with optimal growth at pH 7.0 and at a temperature range of 15–40 °C with a maximal growth rate at 36 °C. Pan97T has a genome size of 6,496,182 bp with a G + C content of 56.2%. 5264 protein-coding genes were identified, of which 2141 genes (41%) encode hypothetical proteins. Based on the phylogenetic analysis, we suggest that Pan97T (DSM 101992T = LMG 29460T) represents a novel species of a novel genus within the family Planctomycetaceae, for which we propose the name Bremerella gen. nov., with strain Pan97T classified as Bremerella volcania sp. nov. Based on our analysis, we also propose the reclassification of Blastopirellula cremea Lee et al. 2013 as Bremerella cremea comb. nov., as this species is considered to be the type species of the novel genus Bremerella.

Planctomycetes of the family Gemmataceae are characterized by large genome sizes and cosmopolitan distribution in freshwater and terrestrial environments but their ecological functions remain poorly understood. In this study, we characterized a novel representative of this family, strain PL17T, which was isolated from a littoral tundra wetland and was capable of growth on xylan and cellulose. Cells of this isolate were represented by pink-pigmented spheres that multiplied bybudding and occurred singly or in short chains and aggregates. Strain PL17 T was obligately aerobic, mildly acidophilic chemoorganotrophic bacterium, which displayed good tolerance of low temperatures. The majorfatty acids were C18:0, C16:1ω5, and βOH-C 16:1; the major polar lipid was trimethylornithine. The genome of strain PL17T consisted of a 9.83 Mb chromosome and a 24.69 kb plasmid. The G + C contents of the chromosomal and plasmid DNA were 67.4 and 62.3 mol%, respectively. Over 8900 potential protein-coding genes were identified in the genome including a putative cellulase that contains a domain from the GH5 family of glycoside hydrolases. The genome of strain PL17T contained one linked and one unlinked rRNA operons with16S rRNA gene sequences displaying 94.5% similarity to that in Gemmata obscuriglobus UQM2246T. Based on the results of comparative phenotypic, chemotaxonomic and phylogenomic analyses, we propose to classify strain PL17T (= CECT 9407T = VKMB-3467T) as representing a novel genus and species of the family Gemmataceae, Frigoriglobus tundricola gen. nov., sp. nov.

The phylum Planctomycetes comprises bacteria with peculiar and very unique characteristics among prokaryotes. In marine environments, macroalgae biofilms are well known for harboring planctomycetal diversity. Here, we describe a novel isolate obtained from the biofilm of the red alga Chondrus crispus collected at a rocky beach in Porto, Portugal. The novel strain LzC2T is motile, rosette-forming with spherical- to ovoid-shaped cells. LzC2T forms magenta- to pinkish-colored colonies in M13 and M14 media. Transmission and scanning electron microscopy observations showed a division by polar and lateral budding. Mother cells are connected to the daughter cells by a tubular neck-like structure. The strain requires salt for growth. Vitamins are not required for growth. Optimal growth occurs from 15 to 30◦C and within a pH range from 5.5 to 10.0. Major fatty acids are anteiso-C15:0 (54.2%) and iso-C15:0 (19.5%). Phosphatidylglycerol, diphosphatidylglycerol and an unidentified glycolipid represent the main lipids and menaquinone 6 (MK-6) is the only quinone present. 16S rRNA gene-based phylogenetic analysis supports the affiliation to the phylum Planctomycetes and family Planctomycetaceae, with Alienimonas as the closest relative. Strain LzC2T shares 97% 16S rRNA gene sequence similarity with Alienimonas californiensis. LzC2T has a genome size of 5.3 Mb and a G+C content of 68.3%. Genotypic and phenotypic comparison with the closest relatives strongly suggest that LzC2T (=CECT 30038T=LMG XXXT) is a new species of the genus Alienimonas, for which we propose the name Alienimonas chondri sp. nov., represented by LzC2T as type strain. 16S rRNA gene accession number: GenBank = MN757873.1. Genome accession number: GenBank = WTPX00000000. This research was partially supported by the Strategic Funding UID/Multi/04423/2019 through national funds provided by FCT – Foundation for Science and Technology and European Regional Development Fund (ERDF), in the framework of the program PT2020, by the Structured Program of R&D&I INNOVMAR–Innovation and Sustainability in the Management and Exploitation of Marine Resources, reference Norte-01-0145-FEDER-NORTE-01-0145-FEDER-000035 (grant NOVELMAR/BI/2018-064) and by Fundação para a Ciência e Tecnologia (Ph.D. grant SFRH/BD/145577/2019).

Aims To explore the role of anaerobic ammonium oxidation (anammox) in nitrogen removal in freshwater marshes. Methods and results The 16S rRNA gene sequences of Candidatus Kuenenia and Candidatus Brocadia were simultaneously detected in the sediment of freshwater marshes of Green Bay Wetland that is located in Eastern China by using Illumina-based sequencing of the total bacterial 16S rRNA genes, and Candidatus Brocadia comprised more than 80% of the total anammox-related sequences. The abundance of anammox bacteria was determined by quantitative PCR on their hydrazine synthase (hzs) genes, which ranged from 3·13 × 104 to 1·58 × 105 copies per g sediment with little temporal variation. The potential anammox rates measured by 15 N-stable isotope pairing technique were 0·78-5·37 nmol N g-1 sediment per h, accounting for 4·3-38·5% of total sediment dinitrogen gas (N2 ) production. Both the anammox activity and its contribution to N2 production were sensitive to temporal variation and correlated well with the sediment NO3 - content. To further examine the nitrogen removal potential via anammox, batch culture was set-up to enrich anammox bacteria from the marsh sediments. Both the activity and abundance of anammox bacteria increased significantly after 6 months of incubation, varying from 61·6 to 95·8 nmol N g-1 sediment per h and 2·86 × 105 to 6·58 × 105 copies per g sediment respectively. Conclusions Our results revealed the great potential of anammox in nitrogen removal in freshwater marshes. Significance and impact of the study This is the first study to show the anammox activity and its temporal variation in freshwater marsh sediments, which improved our understanding of nitrogen removal mechanisms in freshwater marshes.

Planctomycetes are ubiquitous, environmentally and biotechnologically important bacteria that are key players in global carbon and nitrogen cycles. Ever since their first discovery in the 1920s they seemed to blur the prokaryote /eukaryote dichotomy. After initially being described as fungi and reclassified as bacteria later, they were still thought to feature a nucleus-like compartment surrounding their highly condensed DNA. Also, an endocytosis-like uptake mechanism for macromolecules was described. Besides these eukaryotic hallmark traits, Planctomycetes seemed to lack typical bacterial features such as a peptidoglycan cell wall or the universal bacterial cell division protein FtsZ, while mostly dividing by polar budding instead of binary fission. Thus, Planctomycetes were speculated to be ancestral to both, bacteria and eukaryotes. With the advent of novel microscopic techniques, along with the development of genetic tools for Planctomycetes, some of these hypotheses were revisited. Surprisingly, Planctomycetes were found to possess a peptidoglycan cell wall and to comprise a cell plan comparable to other Gram-negative bacteria as the nucleus-like structure is rather an invagination of the cytoplasmic membrane than a cohesive compartment. These finding challenge the idea of a eukaryotic ancestry of the phylum, as Planctomycetes now appear similar, yet distinct to other bacteria.