Polyphosphate Content Research Articles

Defining patterns in the fire protection of wood with reactive coating

An issue related to using a weatherproof reactive coating for fire protection of wood is to ensure resistance to high-temperature flame via application technology. Therefore, the object of research was the fire-retardant properties of reactive coating based on mixtures of organic-inorganic substances during interaction with flame. It has been proven that the samples of the reactive coating represent an accumulation of fine-dispersed equally sized substances surrounded by a polymer binder, which begin to decompose under thermal action; in particular, ammonium polyphosphate decomposes and releases phosphoric acid. That leads to the dehydration of pentaerythrite with the formation of soot while the decomposition of melamine is accompanied by the release of non-combustible gases that cause the soot to foam, thereby forming foamcoke. The mechanism of fire protection of wood has been established, which is related to the decomposition of flame retardants under the influence of temperature, the release of non-combustible gases, and the formation of a non-flammable coke residue. Thus, when the content of ammonium polyphosphate and pentaerythrite in the reactive coating was increased by 5 %, the volume of combustible gases decreased by more than 11 %, and the volume of nitrogen increased by more than 10 %. When their content was increased by 14 %, the volume of combustible gases decreased by more than 2 times, and the volume of nitrogen increased by more than 1.45 times. That also affected the formation of a foamcoke layer, which was recorded at the lowest content of ammonium polyphosphate at the level of 12 mm and increased for higher values up to 15.5 mm, and the multiplicity of foam increased by 1.25 times. The practical significance is that the results are taken into account when designing the reactive coating. Thus, there are reasons to assert the possibility of targeted regulation of the wood protection process by applying coatings capable of forming a protective layer on the surfacev

Knockout mutations in the genes encoding phosphate transporters impair adaptation of <i>Saccharomyces cerevisiae</i> to ethanol consumption

Phosphate transporters in yeast cells are responsible for phosphorus homeostasis, and also indirectly involved in the regulation of various adaptive processes. One of these processes is the adaptation to ethanol consumption, which requires significant changes in phosphorus metabolism. We demonstrated that knockout mutations in the genes encoding phosphate transporters PHO87, PHO89, PHO90 and PHO91 impair adaptation of Saccharomyces cerevisiae to ethanol consumption at ethanol concentration of 4%. For these mutant strains an extension of the lag phase and in a decrease in the growth rate at the active stage was observed when the cells were cultivated in the medium with 4% ethanol. Mutant cells differ in the content of inorganic polyphosphates, but not orthophosphate, from the parental strain: they contain less long-chain polyphosphates when cultivated on ethanol, but not on glucose. When cultivated on a medium containing 4% ethanol, a strain with a knockout mutation in the PHO84 gene, encoding the transporter of phosphate and divalent metals, as well as knockout strains for the PHM6 and PHM7 genes, responsible for the polyphosphate overplus, did not show any growth differences compared with parent strain in a medium with 4% ethanol. The possible role of phosphate transporters and inorganic polyphosphates in the adaptation of yeast to ethanol consumption is discussed.

The Influence of Knockouts of <i>PPN1</i> Polyphosphatase and <i>VTC4</i> Polyphosphate Synthetase Genes on Growth on Ethanol and Mitochondrial Polyphosphates in <i>Saccharomyces cerevisiae</i>

One of the functions of inorganic polyphosphates (polyP), as compounds with phosphoester bonds, is participation in energy metabolism. Yeast mitochondria contain their own pool of polyphosphates; however, the ways in which these polymers are involved in the functioning of mitochondria in these microorganisms are not well understood. The aim of this work was to identify the effect of knockout mutations of the VTC4 polyphosphate synthetase gene and PPN1 one of the polyphosphatases gene on the content of polyphosphates and polyphosphatase activity in mitochondria of S. cerevisiae and the characteristics of the growth of mutant strains on ethanol. It was shown that knockout of the VTC4 gene led to a significant decrease in the content of polyP in mitochondria. Knockout of the PPN1 gene led to the disappearance of polyphosphatase activity, but only to a slight increase in the content of polyphosphates in mitochondria during growth on glucose. When grown on ethanol, the polyP content in the mitochondria of this strain coincided with that of the parental strain, and in both strains, it was approximately two times less than when grown on glucose. Both mutants are able to grow on a medium with ethanol as a carbon source; however, they are characterized by an elongation of the lag phase upon the transition from glucose consumption to ethanol consumption. It has been suggested that mitochondrial polyphosphates may represent the energy reserve of these organelles, which is necessary for the formation of full-fledged mitochondria during the transition from glycolysis to oxidative phosphorylation.

Synergistic enhancement: Ammonium Polyphosphate's impact on hybrid coating performance against corrosion and fire

AbstractThis research demonstrated the impact of ammonium polyphosphate (APP) content on corrosion resistance and flame retardancy properties of hybrid graphene oxide/halloysite/intumescent flame retardant (GO‐HNT‐IFR) coatings. Electrochemical impedance spectroscopy studied indicates that the GO0.6‐H0.3 coating exhibited superior corrosion resistance (Rct = 2.490 × 109 Ω·cm) compared with hybrid GO‐HNT‐IFR coatings. Tafel polarization data revealed a decrease in polarization resistance, Rp simultaneously increases the corrosion rate, Rcorr of the epoxy coatings containing APP compare with GO0.6‐H0.3 coating. Salt spray test result demonstrated that all epoxy coating filled with hybrid nanofillers maintained excellent surface integrity, preventing corrosion for up to 500 h under controlled accelerated corrosive conditions. A reasonable increment of limited oxygen index up to 12.5% was reported by the addition of 1 phr APP, indicating its best flame retardancy and thermal stability properties among coating samples. The appropriate addition of APP (1 phr) enhanced the flame retardancy and thermal stability properties of hybrid GO‐HNT‐IFR coatings to a certain extent but it is impaired by increasing the APP loading. Transmission electron microscopy results validated the formation of aggregation at high APP loading, consequently affecting coating performances as well as its adhesion strength.

Advances in the cellular biology, biochemistry, and molecular biology of acidocalcisomes.

SUMMARYAcidocalcisomes are organelles conserved during evolution and closely related to the so-called volutin granules of bacteria and archaea, to the acidocalcisome-like vacuoles of yeasts, and to the lysosome-related organelles of animal species. All these organelles have in common their acidity and high content of polyphosphate and calcium. They are characterized by a variety of functions from storage of phosphorus and calcium to roles in Ca2+ signaling, osmoregulation, blood coagulation, and inflammation. They interact with other organelles through membrane contact sites or by fusion, and have several enzymes, pumps, transporters, and channels.

Multiple effects of the PHO91 gene knockout in Ogataea parapolymorpha.

Pho91 is a vacuolar phosphate transporter that exports phosphate from the vacuolar lumen to the cytosol in yeast cells. In this study, we have demonstrated the pleiotropic effects of the PHO91 gene knockout in the methylotrophic yeast Ogataea parapolymorpha (Hansenula polymorpha, Ogataea angusta). The content of both acid-soluble and acid-insoluble inorganic polyphosphate (polyP) in the ∆pho91 cells was slightly higher compared to the strain with wild-type PHO91, when the cells were cultivated on glucose. The pho91-Δ mutations both in O. parapolymorpha and in Saccharomyces cerevisiae diminished resistance to cadmium and increased resistance to manganese and peroxide stresses. The cells of the mutant strain of O. parapolymorpha were unable to consume methanol due to the lack of methanol oxidase activity. We speculate that these effects are associated with the inability of mutant cells to mobilize phosphate from the vacuolar pool and/or defects in the signaling pathways involving phosphate, polyP, and inositol polyphosphates.

Phosphate limitation intensifies negative effects of ocean acidification on globally important nitrogen fixing cyanobacterium

Growth of the prominent nitrogen-fixing cyanobacterium Trichodesmium is often limited by phosphorus availability in the ocean. How nitrogen fixation by phosphorus-limited Trichodesmium may respond to ocean acidification remains poorly understood. Here, we use phosphate-limited chemostat experiments to show that acidification enhanced phosphorus demands and decreased phosphorus-specific nitrogen fixation rates in Trichodesmium. The increased phosphorus requirements were attributed primarily to elevated cellular polyphosphate contents, likely for maintaining cytosolic pH homeostasis in response to acidification. Alongside the accumulation of polyphosphate, decreased NADP(H):NAD(H) ratios and impaired chlorophyll synthesis and energy production were observed under acidified conditions. Consequently, the negative effects of acidification were amplified compared to those demonstrated previously under phosphorus sufficiency. Estimating the potential implications of this finding, using outputs from the Community Earth System Model, predicts that acidification and dissolved inorganic and organic phosphorus stress could synergistically cause an appreciable decrease in global Trichodesmium nitrogen fixation by 2100.

Evaluating the Change Characteristics of the Microstructure of the Modified Plant Asphalt Using Soft Computing to Improve the Road Performance for Green Environment

Due to the diversity of plant asphalt sources and refining processes, the composition and properties of the various plant asphalts are also different. The plant asphalts are used to preserve the green environment. The natural material is eco-friendly; hence, the usage of plant asphalts is getting promoted these days. There are some problems in the road performance of some source plant asphalt, so the change characteristics of the microstructure of the modified plant asphalt are analyzed in this paper. Firstly, the raw materials are prepared, then the experimental plan is made, and finally the microstructure change characteristics of asphalt at different dosages of 0%, 0.25%, 0.5%, 0.75%, and 1% are studied using the soft computing techniques. It is found that with the increase of the content of polyphosphate, the structure of modified asphalt has changed. The most obvious change is that the volume of asphaltenes becomes smaller, the number of asphaltenes increases, the area of asphalt micelle becomes smaller, and the area of dispersion medium becomes larger. The experimental study is performed to guide the right material for road construction which is eco-friendly for maintaining the green environment.

Development and optimization of fire-protective coating composition based on epoxypolymers

The object of research is intumescent fire retardant coatings based on epoxy resins. The research is aimed at the development of mathematical models of the dependence of the swelling rate of intumescent fire retardant coatings on their composition. Considering the complexity of the processes during the formation of a protective carbon layer, it is advisable to select the optimal ratio of the components of an intumescent fire retardant coating experimentally, followed by the construction of mathematical dependences of the swelling ratio on the coating composition. Therefore, experimental studies aimed at developing and optimizing the composition of an intumescent fire retardant coating based on epoxy polymers are an important task. The studies were carried out in accordance with the theory of planning experiments with the construction of an orthogonal compositional plan of the second order. A linear swelling factor was chosen as the response function. Compositions based on the ED-20 epoxy oligomer, cured with polyethylene polyamine and filled with ammonium polyphosphate, aluminum hydroxide, and graphite additive were used for the study. Based on the results of processing the experimental results, a regression equation was obtained and response surfaces were constructed that describe the dependence of the linear swelling coefficient Cs of an intumescent composition based on an epoxy oligomer on the content of ammonium polyphosphate, aluminum hydroxide and graphite additive. A complex relationship is shown between the content of components and the linear swelling coefficient Cs with different ratios of the components. The optimum by the linear swelling coefficient (Cs=68.1) content of the components in the epoxy polymer was determined, amounting to 20 wt. including for ammonium polyphosphate, 15 mass parts including for aluminum hydroxide and 3 mass parts for the graphite additive. However, with such a ratio, the «self-extinguishing» condition is not met (Cs=27 %). Filling the composition with ammonium polyphosphate in an amount of 26.3 mass parts including, aluminum hydroxide 25 mass parts and 3.5 mass parts including graphite additives allows to get an intumescent fire retardant coating with a swelling ratio Cs over 63 and a reduced level of flammability (Ci=31 %)

Single-cell visualization and quantification of trace metals in Chlamydomonas lysosome-related organelles

The acidocalcisome is an acidic organelle in the cytosol of eukaryotes, defined by its low pH and high calcium and polyphosphate content. It is visualized as an electron-dense object by transmission electron microscopy (TEM) or described with mass spectrometry (MS)-based imaging techniques or multimodal X-ray fluorescence microscopy (XFM) based on its unique elemental composition. Compared with MS-based imaging techniques, XFM offers the additional advantage of absolute quantification of trace metal content, since sectioning of the cell is not required and metabolic states can be preserved rapidly by either vitrification or chemical fixation. We employed XFM in Chlamydomonas reinhardtii to determine single-cell and organelle trace metal quotas within algal cells in situations of trace metal overaccumulation (Fe and Cu). We found up to 70% of the cellular Cu and 80% of Fe sequestered in acidocalcisomes in these conditions and identified two distinct populations of acidocalcisomes, defined by their unique trace elemental makeup. We utilized the vtc1 mutant, defective in polyphosphate synthesis and failing to accumulate Ca, to show that Fe sequestration is not dependent on either. Finally, quantitation of the Fe and Cu contents of individual cells and compartments via XFM, over a range of cellular metal quotas created by nutritional and genetic perturbations, indicated excellent correlation with bulk data from corresponding cell cultures, establishing a framework to distinguish the nutritional status of single cells.

Xenotropic and polytropic retrovirus receptor 1 regulates procoagulant platelet polyphosphate

Polyphosphate is a procoagulant inorganic polymer of linear-linked orthophosphate residues. Multiple investigations have established the importance of platelet polyphosphate in blood coagulation; however, the mechanistic details of polyphosphate homeostasis in mammalian species remain largely undefined. In this study, xenotropic and polytropic retrovirus receptor 1 (XPR1) regulated polyphosphate in platelets and was implicated in thrombosis in vivo. We used bioinformatic analyses of omics data to identify XPR1 as a major phosphate transporter in platelets. XPR1 messenger RNA and protein expression inversely correlated with intracellular polyphosphate content and release. Pharmacological interference with XPR1 activity increased polyphosphate stores, led to enhanced platelet-driven coagulation, and amplified thrombus formation under flow via the polyphosphate/factor XII pathway. Conditional gene deletion of Xpr1 in platelets resulted in polyphosphate accumulation, accelerated arterial thrombosis, and augmented activated platelet-driven pulmonary embolism without increasing bleeding in mice. These data identify platelet XPR1 as an integral regulator of platelet polyphosphate metabolism and reveal a fundamental role for phosphate homeostasis in thrombosis.

Requirement of the exopolyphosphatase gene for cellular acclimation to phosphorus starvation in a cyanobacterium, Synechocystis sp. PCC 6803

Polyphosphate, which is ubiquitous in cells in nature, is involved in a myriad of cellular functions, and has been recently focused on its metabolism related with microbial acclimation to phosphorus-source fluctuation. In view of the ecological importance of cyanobacteria as the primary producers, this study investigated the responsibility of polyphosphate metabolism for cellular acclimation to phosphorus starvation in a cyanobacterium, Synechocystis sp. PCC 6803, with the use of a disruptant (Δppx) as to the gene of exopolyphosphatase that is responsible for polyphosphate degradation. Δppx was similar to the wild type in the cellular content of polyphosphate to show no defect in cell growth under phosphorus-replete conditions. However, under phosphorus-starved conditions, Δppx cells were defective in a phosphorus-starvation dependent decrease of polyphosphate to show deleterious phenotypes as to their survival and the stabilization of the photosystem complexes. These results demonstrated some crucial role of exopolyphosphatase to degrade polyP in the acclimation of cyanobacterial cells to phosphorus-starved conditions. Besides, it was found that ppx expression is induced in Synechocystis cells in response to phosphorus starvation through the action of the two-component system, SphS and SphR, in the phosphate regulon. The information will be a foundation for a fuller understanding of the process of cyanobacterial acclimation to phosphorus fluctuation.

In Vitro and In Vivo Studies of Biodegradability and Biocompatibility of Poly(εCL)-b-Poly(EtOEP)-Based Films.

The control of surface bioadhesive properties of the subcutaneous implants is essential for the development of biosensors and controlled drug release devices. Poly(alkyl ethylene phosphate)-based (co)polymers are structurally versatile, biocompatible and biodegradable, and may be regarded as an alternative to poly(ethylene glycol) (PEG) copolymers in the creation of antiadhesive materials. The present work reports the synthesis of block copolymers of ε-caprolactone (εCL) and 2-ethoxy-1,3,2-dioxaphospholane-2-oxide (ethyl ethylene phosphate, EtOEP) with different content of EtOEP fragments, preparation of polymer films, and the results of the study of the impact of EtOEP/εCL ratio on the hydrophilicity (contact angle of wetting), hydrolytic stability, cytotoxicity, protein and cell adhesion, and cell proliferation using umbilical cord multipotent stem cells. It was found that the increase of EtOEP/εCL ratio results in increase of hydrophilicity of the polymer films with lowering of the protein and cell adhesion. MTT cytotoxicity test showed no significant deviations in toxicity of poly(εCL) and poly(εCL)-b-poly(EtOEP)-based films. The influence of the length of poly(EtOEP)chain in block-copolymers on fibrotic reactions was analyzed using subcutaneous implantation experiments (Wistar line rats), the increase of the width of the fibrous capsule correlated with higher EtOEP/εCL ratio. However, the copolymer-based film with highest content of polyphosphate had been subjected to faster degradation with a formation of developed contact surface of poly(εCL). The rate of the degradation of polyphosphate in vivo was significantly higher than the rate of the degradation of polyphosphate in vitro, which only confirms an objective value of in vivo experiments in the development of polymer materials for biomedical applications.

Using scanning electron microscopy, x-ray diffraction and IR spectroscopy to study the ageing of intumescent fire-proof coatings

Introduction. The fire protection of metal structures is a relevant present-day problem; its solution implies better fire resistance performance of structures attainable through the application of intumescent fire-proof coatings whose service life expectancy is limited.Goals and objectives. Comprehensive studies of domestically made coating samples were performed to analyze the changes in the chemical composition of intumescent coatings containing ammonium polyphosphate, melamine, and pentaerythritol. The samples were exposed to artificial climatic ageing (3, 6, and 9 years). Methods. Optical and scanning electron microscopies were used to study the appearance of samples, the morphology of inclusions and the surface microstructure. X-ray diffraction and IR spectroscopy were employed to study the phase and structural states of samples, and the swelling ratio of fire-proof coatings was also examined.Results and discussion. It’s been found out that the swelling ratio of samples goes down to a significant extent as the time progresses, and when the residual life of a coating reaches 30 %, the fire resistance limit of the structure goes down. Sample ageing is the reason for gradual phase composition changes due to the melamine content reduction by 40 %, ammonium polyphosphate content reduction by 15 % and redistribution of other components that change the microstructure of coatings, as well as their fire retarding properties.Conclusions. The changes, influencing the ability of a coating to maintain its fire retarding efficiency as declared by the manufacturer, take place in the course of operation of a coating exposed to external factors. The regularities, identified by virtue of this research, can be used to study the samples taken at fire-proofed facilities to identify deviations from the initial condition of a coating and to forecast its actual service life.

Lead accumulation in photosynthetic Euglena gracilis depends on polyphosphates and calcium.

Worldwide increasing levels of lead in water systems require the search for efficient ecologically friendly strategies to remove it. Hence, lead accumulation by the free-living algae-like Euglena gracilis and its effects on cellular growth, respiration, photosynthesis, chlorophyll, calcium, and levels of thiol- and phosphate-molecules were analyzed. Photosynthetic cells were able to accumulate 4627mg lead/kgDW after 5 days of culture with 200μMPb2+. Nevertheless, exposure to 50, 100 and 200μM Pb2+ for up to 8 days did not modify growth, viability, chlorophyll content and oxygen consumption/production. Enhanced biosynthesis of thiol molecules and polyphosphates, i.e. the two canonical metal ion chelation mechanisms in E.gracilis, was not induced under such conditions. However, in cells cultured in the absence of phosphate, lead accumulation and polyphosphate content markedly decreased, while culturing in the absence of sulfate did not modify the accumulation of this metal. In turn, the total amount of intracellular calcium slightly increased as the amount of intracellular lead increased, whereas under Ca2+ deficiency lead accumulation doubled. Therefore, the results indicated that E.gracilis is highly resistant to lead through mechanisms mediated by polyphosphates and Ca2+ and can in fact be classified as a lead hyperaccumulator microorganism.

Thermal Behavior of Polyurethane Ionomers Based on Amino Ethers of Orthophosphoric Acid

The products of triethanolamine- and triethylamine-catalyzed reactions of etherification of orthophosphoric acid using poly(oxypropylene glycol)-1000 are studied. It is shown that the nature of tertiary amine markedly influences the completeness of the etherification reaction. When using triethanolamine, its hydroxyl groups are also involved in the etherification of orthophosphoric acid. The resultant tertiary ammonium, which is a central unit of the synthesized branched amino ethers of orthophosphoric acid, is responsible for incomplete etherification and existence of space-separated ionic pairs in the structure of amino ethers. In the case of triethylamine, the etherification of orthophosphoric acid occurs almost completely to yield polyphosphates. The thermal behavior of ionomeric and nonionomeric polyurethanes is investigated. It is found that, for polyurethanes containing ionic groups, the glass transition temperature is much higher than that of nonionomeric polyurethanes. It is shown that phosphorus-containing nonionomeric polyurethanes possess higher thermal stability in inert atmosphere than phosphorous-containing polyurethane ionomers. The onset temperature of the thermal degradation for nonionomeric polyurethanes decreases considerably with an increase in the content of polyphosphates. Polyurethane ionomers synthesized using phospholipids feature a lower thermal stability than polyurethanes based on amino ethers of orthophosphoric acid.

Phenotypic dynamics in polyphosphate and glycogen accumulating organisms in response to varying influent C/P ratios in EBPR systems

This study employed molecular tools and single cell Raman micro-spectroscopy techniques to reveal the single cell- and population-level phenotypic dynamics and changes in functionally relevant organisms, namely polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), in response to influent loading readily biodegradable carbon to phosphorus ratio (C/P) changes in enhanced biological phosphorus removal (EBPR) systems. The results, for the first time, provided direct and cellular evidence confirming the adaptive anaerobic metabolic pathway shifts in PAOs in response to influent loading variations. Increase in influent readily biodegradable carbon to phosphorus (C/P) ratio from 20 to 50 led to nearly 50% decline in polyphosphate content and drastic rise of intracellular polyβhydroxybutyrate (PHB) to polyphosphate (polyP) ratio by nearly 6 times in PAOs, indicating corresponding diminishing reliance on polyP hydrolysis for energy as P becomes limiting. Influent carbon availability surge also impacted the intracellular carbon polymers in GAOs, with significant increase in the mean PHB content level but no observed changes in the intracellular glycogen level. Furthermore, the Raman-based quantification of differentiated intracellular polymer content associated with PAOs and GAOs, revealed new insights into the quantitative shift in intracellular carbon storage distribution between the two populations and their variations between the two carbon polymers (PHB, Glycogen). In summary, this investigation revealed high-resolution cellular level information regarding the metabolic flexibility in PAOs, phenotypic stoichiometry changes and carbon flux and distribution among PAOs and GAOs, in response to influent loading conditions. The new information will contribute to improvement in mechanistic EBPR modeling and design.

Inorganic Polyphosphate and Physiological Properties of Saccharomyces cerevisiae Yeast Overexpressing Ppn2.

The effect of the yeast endopolyphosphatase Ppn2 overproduction on the metabolism of inorganic polyphosphates in Saccharomyces cerevisiae yeast was studied. Expression of the PPN2 gene under control of the strong constitutive promoter of glyceraldehyde 3-phosphate dehydrogenase gene (PKG1) led to a significant increase in the endopolyphosphatase activity stimulated by cobalt/zinc ions. This activity was present in both soluble and membrane subcellular fractions; it was higher toward long-chain polyphosphates and could be stimulated by ADP. The content of short-chain polyphosphates in the cells of the overexpressing strain was ~2.5 times higher compared to the parent strain. The cells overexpressing Ppn2 were more resistant to peroxide and alkali. The role of short-chain polyphosphates in the adaptation to these stress factors is discussed.

Analysis of Polyphosphate during the Enhanced Biological Phosphorus Removal process using Fourier Transform Infrared (FTIR) spectroscopy

Two enhanced biological phosphorus removal (EBPR) reactors were operated in synthetic wastewater with different Chemical Oxygen Demand/Phosphorus (COD/P) ratios. The sludge samples at different sample times were lyophilized and characterized by Fourier Transform Infrared (FTIR) spectroscopy. Results showed that the infrared spectral curves from two reactors were similar but the intensities were different at specific wavenumbers. The spectral intensities at 1260cm-1 and 890cm-1 of the sludge samples from the reactor at low COD/P ratios were relatively stronger, but those of the reactor at high COD/P ratios were relatively weaker. The principal component projection plot of FTIR spectra analyzed with principal components analysis (PCA) showed that the sludge samples at the same COD/P ratios assembled together implicating the principal component projection plot could discriminate the sludge samples from different reactor. The infrared peak near 890cm-1 was separated and integrated with Gaussian peak fitting method. The integrated areas were correlated to the polyphosphate content in the sludge. Results showed that the prediction values were in good accordance with those determined by chemical method. This work provides a new method for the recognition of polyphosphate in sludge and provides a basis for the rapid determination of polyphosphate.

The potential for polyphosphate metabolism in Archaea and anaerobic polyphosphate formation in Methanosarcina mazei

Inorganic polyphosphate (polyP) is ubiquitous across all forms of life, but the study of its metabolism has been mainly confined to bacteria and yeasts. Few reports detail the presence and accumulation of polyP in Archaea, and little information is available on its functions and regulation. Here, we report that homologs of bacterial polyP metabolism proteins are present across the major taxa in the Archaea, suggesting that archaeal populations may have a greater contribution to global phosphorus cycling than has previously been recognised. We also demonstrate that polyP accumulation can be induced under strictly anaerobic conditions, in response to changes in phosphate (Pi) availability, i.e. Pi starvation, followed by incubation in Pi replete media (overplus), in cells of the methanogenic archaeon Methanosarcina mazei. Pi-starved M. mazei cells increased transcript abundance of the alkaline phosphatase (phoA) gene and of the high-affinity phosphate transport (pstSCAB-phoU) operon: no increase in polyphosphate kinase 1 (ppk1) transcript abundance was observed. Subsequent incubation of Pi-starved M. mazei cells under Pi replete conditions, led to a 237% increase in intracellular polyphosphate content and a > 5.7-fold increase in ppk1 gene transcripts. Ppk1 expression in M. mazei thus appears not to be under classical phosphate starvation control.