[Ten-year Trend Analysis of Eutrophication Status and the Related Causes in Lake Hongze].

In order to propose pertinent suggestions regarding eutrophication control for Lake Hongze, we used monthly monitoring data from 2011 to 2020 to elucidate the spatiotemporal changing characteristics of eutrophic status and the relevant driving factors. As the main river entering Lake Hongze, River Huaihe experienced an increase in permanganate index and a decrease in TN in the last 10 years. Meanwhile, Secchi depth, TP, and permanganate index increased, whereas TN and Chl-a concentration decreased significantly in Lake Hongze. As a result, the eutrophic status TLI index of Lake Hongze declined over the past 10 years. The change trend of TLI in Lake Hongze differed spatially. As the main water passage of River Huaihe, the algal biomass was lower in the eastern region than that in the other two lake regions, regardless of the relatively high nutrient concentration, due to the short water retention time. Furthermore, the water quality of River Huaihe improved; thus, the TLI index decreased significantly in the eastern lake region. The northern region had a high coverage of aquatic vegetation, which not only reduced the concentration of water nutrients but also provided a habitat for zooplankton and fish, effectively inhibiting algal growth. Thus, the TLI index was lowest among the three lake areas and showed a downward trend over the last 10 years. In the western region, the algal biomass was the highest due to the intensification of phosphorus release from sediment in summer. Thus, the TLI index was the highest and had not improved in the past 10 years. There were also significant seasonal differences in the TLI of Lake Hongze, which was highest in summer, due to the relatively high algal biomass. Moreover, the algal biomass in summer was mainly affected by the concentration of nitrate. According to the spatiotemporal distribution characteristics of eutrophic status and the impacting factors in Lake Hongze, corresponding measures for eutrophication control should be taken for different seasons and lake areas.

A Growing Link between Circadian Rhythms, Type 2 Diabetes Mellitus and Alzheimer's Disease.

Type 2 diabetes mellitus (T2DM) patients are at a higher risk of developing Alzheimer's disease (AD). Mounting evidence suggests the emerging important role of circadian rhythms in many diseases. Circadian rhythm disruption is considered to contribute to both T2DM and AD. Here, we review the relationship among circadian rhythm disruption, T2DM and AD, and suggest that the occurrence and progression of T2DM and AD may in part be associated with circadian disruption. Then, we summarize the promising therapeutic strategies targeting circadian dysfunction for T2DM and AD, including pharmacological treatment such as melatonin, orexin, and circadian molecules, as well as non-pharmacological treatments like light therapy, feeding behavior, and exercise.

Evaluation of the key active ingredients of 'Radix Astragali and Rehmanniae Radix Mixture' and related signaling pathways involved in ameliorating diabetic foot ulcers from the perspective of TCM-related theories.

BACKGROUND AND OBJECTIVE: Traditional Chinese Medicine is more inclined to holistic thinking than most modern pharmacological research. The multiple components and targets of traditional Chinese medicine have become a stumbling block in the study of drug action mechanisms in the life sciences. The current study aimed to reveal the active ingredients of "Radix Astragali and Rehmanniae Radix Mixture (RA-RRM)" involved in ameliorating diabetic foot ulcers and to analyze the related signaling pathways. METHOD: The Traditional Chinese Medicine Systems Pharmacology Data base and Analysis Platform (TCMSP) was used to screen the active ingredients in RA-RRM based on the evaluation of the molecular weight (MW), bioavailability (OB), and transport of these active ingredients across intestinal epithelial cells (Caco-2) and the blood-brain barrier (BBB). The PubChem database was used to illustrate the structural formula and SMILES of these active ingredients in RA-RRM. The Swiss Target Prediction Database, DrugBank, Genecards, and CTD were used to predict the targets that were correlated with RA-RRM-based treatment of diabetic foot ulcers. Cytoscape 3.7.0 software was used to construct the protein/gene interaction network diagram, compound target interaction network diagram, and target pathway network diagram for these active ingredients in the amelioration of diabetic foot ulcers in RA-RRM. Topological parameter calculations of target information using Cytoscape 3.7.0 software yielded drug-disease targets were used to reveal the relationship between key active ingredients in RA-RMM and targets of interest for the treatment of diabetic foot. The disease targets of drug action were imported into the David database (GO and KEGG analysis) to analyze the enriched pathways and biological processes. RESULTS: The following results were obtained using the abovementioned screening and analysis. Fourteen key active ingredients in RA-RRM and 309 targets were found; among them, 85 targets were found to be related to diabetic foot ulcers using TCMSP. Twenty-three biological processes, 7 cell components and 14 molecular functions were found to ameliorate diabetic foot ulcers using GO analysis. In addition, 29 signaling pathways were found to be involved in RA-RRM-induced amelioration, including the NF-κB, TNF, TGF-ß, VEGF, and HIF-1 signaling pathways, using KEGG analysis. CONCLUSIONS: Based on current available evidence obtained from the abovementioned data/information databases and based on the perspective of TCM-related theories, the present study revealed the key active ingredients in RA-RRM and related signaling pathways in the treatment of diabetic foot ulcers, promoting further studies on and clinical applications of RA-RRM.

Luteolin combined with low-dose paclitaxel synergistically inhibits epithelial-mesenchymal transition and induces cell apoptosis on esophageal carcinoma in vitro and in vivo.

Although paclitaxel is a promising frontline chemotherapy agent for various malignancies, the clinical applications have been restricted by side effects, drug resistance, and cancer metastasis. The combination of paclitaxel and other agents could be the promising strategies against malignant tumor, which enhances the antitumor effect through synergistic effects, reduces required drug concentrations, and also suppresses tumorigenesis in multiple ways. In this study, we found that luteolin, a natural flavonoid compound, combined with low-dose paclitaxel synergistically regulated the proliferation, migration, epithelial-mesenchymal transition (EMT), and apoptosis of esophageal cancer cells in vitro, as well as synergistically inhibited tumor growth without obvious toxicity in vivo. The molecular mechanism of inhibiting cell migration and EMT processes may be related to the inhibition of SIRT1, and the mechanism of apoptosis induction is associated with the reactive oxygen species (ROS)/c-Jun N-terminal kinase (JNK) pathway-mediated activation of mitochondrial apoptotic pathway.

The spatial distribution of the photosynthetic picoeukaryotes community structure in Lake Hongze.

The spatial dynamics of picophytoplankton were investigated by flow cytometry and high-throughput sequencing in Lake Hongze, a large river-connecting lake. Picophytoplankton were mainly composed of phycocyanin-rich picocyanobacteria (PCY) and photosynthetic picoeukaryotes (PPEs). Picocyanobacteria was the dominant picophytoplankton group since the contribution of PPEs to total picophytoplankton was only 11.78%. However, PPEs were highly diverse and were composed of Chlorophyta, Bacillariophyta and Chrysophyceae. Environmental factors showed spatial differences, particularly in total phosphorus (TP), suspended solids (SS) and chemical oxygen demand (CODMn), which showed relatively high concentrations around the river channel. The abundances of PPEs and PCY showed similar spatial patterns, which were relatively low in the river course since they were negatively related to SS and CODMn. The top 10 OTUs contributed 79.18% of the total PPEs reads and affiliated with main species in PPEs. CCA results showed that, PPEs community composition was significantly impacted by temperature and DO at sites away from river channel, while was only influenced by nitrite at sites around the river channel.

Light induces gene expression to enhance the synthesis of storage reserves in Brassica napus L. embryos.

KEY MESSAGE: In this manuscript, we disclosed the influence of light on the accumulation of storage reserves in B. napus embryos.1.Light induced the gene expression in the developing embryos of B. napus.2.Light promoted the starch synthesis in chloroplasts of B. napus embryos.3.Light enhanced the metabolic activity of storage reserve synthesis in B. napus embryos. Light influences the accumulation of storage reserves in embryos, but the molecular mechanism was not fully understood. Here, we monitored the effects of light on reserve biosynthesis in Brassica napus by comparing embryos from siliques grown in normal light conditions to those that were shaded or masked (i.e., darkened completely). Masked embryos developed more slowly, weighed less, and contained fewer proteins and lipids than control embryos. They also had fewer and smaller oil bodies than control embryos and lacked chloroplasts, where starch grains are usually synthesized. The levels of most amino acids, carbohydrates, and fatty acids were higher in masked embryos than in control or shaded embryos, whereas the levels of these metabolites in the masked endosperms were lower than those in control and shaded endosperm. Transcriptome analysis indicated that genes involved in photosynthesis (42 genes), amino acid biosynthesis (51 genes), lipid metabolism (61 genes), and sugar transport (13 genes) were significantly repressed in masked embryos. Our results suggest that light contributes to reserve accumulation in embryos by inducing the expression of metabolic genes, thereby enhancing the biosynthesis of storage reserves.

Evaluation of nine active components of Lu-Jiao Fang in normal and hypertrophic rat myocardia via LC-MS/MS.

Lu-Jiao Fang (LJF), a traditional Chinese medicine prescription, can improve the cardiac function of chronic heart failure (CHF) patients; however, knowledge about the cardiac distribution of LJF, especially in CHF animal models, is rather limited. This work aimed to explore the cardiac distribution of LJF in pressure overload-induced CHF rats at the last gavage administration of LJF after 30 weeks of treatment. LC-MS/MS methods for analyzing nine active components (i.e. loganin, hesperidin, epimedin C, icariin, psoralen, isopsoralen, baohuoside I, morroniside and specnuezhenide) of LJF in cardiac tissue samples were established, and the components were then analyzed in left ventricular wall (LVW) and right ventricular wall (RVW) in parallel at same time point postdose for three dose groups. The results showed that most analytical component levels in LVW (hypertrophic myocardium) were only 39-74% of those in RVW (normal myocardium); however, psoralen and isopsoralen levels in LVW were equal to or even greater than the levels in RVW, suggesting that the hypertrophic myocardium tissue affinity of psoralen and isopsoralen might overcome the negative effect of decreased blood flow on distribution. This study indicated that the pathological state may influence drug distribution, and the efficacy of psoralen and isopsoralen for improving CHF deserves further investigation.

Correlation analysis of the transcriptome and metabolome reveals the regulatory network for lipid synthesis in developing Brassica napus embryos.

KEY MESSAGE: In this manuscript, we explored the key molecular networks for oil biosynthesis with the transcriptome and metabolome of B. napus embryo at different developmental stages. Brassica napus (B. napus) is an important oil crop worldwide, yet the molecular pathways involved in oil biosynthesis in seeds are not fully understood. In this study, we performed a combined investigation of the gene expression profiles and metabolite content in B. napus seeds at 21, 28 and 35 days after flowering (DAF), when seed oil biosynthesis takes place. The total triacylglycerol (TAG) content in seed embryos increased over the course of seed maturation, and was accompanied by changes in the fatty acid profile, an increase in lipid droplets, and a reduction in starch grains. Metabolome analysis showed that the total amino acid, free fatty acid and organic acid contents in seed embryos decreased during seed maturation. In total, the abundance of 76 metabolites was significantly different between 21 and 28 DAF, and 68 metabolites changed in abundance between 28 and 35 DAF. Transcriptome analysis showed that the set of genes differentially expressed between stages was significantly enriched in those related to lipid metabolism, transport, protein and RNA metabolism, development and signaling, covering most steps of plant lipid biosynthesis and metabolism. Importantly, the metabolite and gene expression profiles were closely correlated during seed development, especially those associated with TAG and fatty acid biosynthesis. Further, the expression of major carbohydrate metabolism-regulating genes was closely correlated with carbohydrate content during seed maturation. Our results provide novel insights into the regulation of oil biosynthesis in B. napus seeds and highlights the coordination of gene expression and metabolism in this process.

Sodium Butyrate Supplementation Alleviates the Adaptive Response to Inflammation and Modulates Fatty Acid Metabolism in Lipopolysaccharide-Stimulated Bovine Hepatocytes.

This study aimed to evaluate whether sodium butyrate (SB) attenuates the hepatic response to LPS-induced inflammation in bovine hepatocytes. Hepatocytes isolated from cows at ∼160 days in milk (DIM) were exposed to 0.5 mmol/L SB for 18 h as pretreatment. Cells pretreated with SB were used for the SB group, and those subjected to 4 µg/mL lipopolysaccharide (LPS) challenge for 6 h were used for the lipopolysaccharide pretreated with SB (LSB) group. The LPS-challenged hepatocytes showed increases in TNF-α and IL-6 production in culture medium (37 ± 11, P < 0.05); these increases were attenuated by pretreatment with SB in the LSB group (267 ± 4, P < 0.05). Compared to that in LPS-treated cells, the phospho-p65 and phospho-IκBα protein expression and nuclear translocation were suppressed when SB was added. Genes ( SREBP1c, SCD1, and DGAT1) and proteins (SREBP1c and SCD1) related to fatty acid metabolism were upregulated in LSB cells compared to those in LPS-treated cells ( P < 0.05). The ratios of phospho-AMPKα to AMPKα (0.32 ± 0.03 vs 0.70 ± 0.07) and phospho-ACCα to ACCα were decreased (0.81 ± 0.06 vs 2.06 ± 0.16) ( P < 0.05) in the LSB group. SB pretreatment reversed the histone H3 deacetylation that was increased by LPS stimulation in bovine hepatocytes (0.54 ± 0.02 vs 1.27 ± 0.11, P < 0.05). Our results suggest that SB pretreatment suppresses the hepatocyte changes that occur during the LPS-induced inflammatory response, which is accompanied by enhanced fatty acid synthesis, downregulated fatty acid oxidation, and histone H3 deacetylation, thus neutralizing the negative effects of infection.

Increased cardiac distribution of mono-PEGylated Radix Ophiopogonis polysaccharide in both myocardial infarction and ischemia/reperfusion rats.

Although PEGylation plays an important role in drug delivery, knowledge about the distribution behavior of PEGylated drugs in ischemic myocardia is rather limited compared to nanoparticles. This work therefore aims to characterize the targeting behavior of the anti-myocardial ischemic mono-PEGylated conjugates of Radix Ophiopogonis polysaccharide (ROP) in two clinically relevant animal models, ie, the myocardial infarction (MI) model and the ischemia/reperfusion (IR) model. To determine the effect of the molecular size of conjugates, two representative conjugates (20- and 40-kDa polyethylene glycol mono-modified ROPs), with hydrodynamic size being approximately and somewhat beyond 10 nm, respectively, were studied in parallel at three time points postdose after a method for determining them quantitatively in biosamples was established. The results showed that the cardiac distribution of the two conjugates was significantly enhanced in both MI and IR rats due to the enhanced permeability and retention effect induced by ischemia. In general, the cardiac targeting efficacy of the conjugates in MI and IR rats was approximately 2; however, different changing in targeting efficacy with time was observed between MI and IR rats and also between the conjugates. Although the enhanced permeability and retention effect-based targeting efficacy for mono-PEGylated ROPs was not high, they, as dissolved macromolecules, are prone to diffusion in the cardiac interstitium space, and thus, facilitate the drug to reach perfusion-deficient and nonperfused areas. These findings are helpful in choosing the cardiac targeting strategy.

Injectable long-acting systems for Radix Ophiopogonis polysaccharide based on mono-PEGylation and in situ formation of a PLGA depot.

BACKGROUND: Radix Ophiopogonis polysaccharide (ROP), a highly hydrophilic macromolecule, has a unique anti-ischemic action in the myocardium. One of the main problems with its use is its relatively short half-life in vivo. To solve this problem, injectable long-acting drug delivery systems, which combine mono-PEGylation (PEG, polyethylene glycol) with the in situ formation of poly(D,L-lactide-co-glycolide) copolymer (PLGA) depots, were tested in this study. METHODS: Through a moderate coupling reaction between 20 kDa amino-terminated methoxy-PEG and excessive ROP with activated hydroxyls, a long-circulating and bioactive mono-PEGylated ROP was prepared and characterized. A reasonable and applicable range of PLGA formulations loaded with the mono-PEGylated ROP were prepared, characterized, and evaluated in vivo. RESULTS: Relative to ROP, the half-life of which was only 0.5 hours, the conjugate alone, following subcutaneous administration, showed markedly prolonged retention in the systemic circulation, with a mean residence time in vivo of approximately 2.76 days. In combination with in situ-forming PLGA depots, the residence time of the conjugate in vivo was prolonged further. In particular, a long-lasting and steady plasma exposure for nearly a month was achieved by the formulation comprising 40% 30 kDa PLGA in N-methyl-2-pyrrolidone. CONCLUSION: Long-lasting and steady drug exposure could be achieved using mono-PEGylation in combination with in situ formation of PLGA depots. Such a combination with ROP would be promising for long-term prophylaxis and/or treatment of myocardial ischemia. For high-dose and highly hydrophilic macromolecular drugs like ROP, more than one preparation technology might be needed to achieve week-long or month-long delivery per dosing.

The dynamics of microcystis genotypes and microcystin production and associations with environmental factors during blooms in Lake Chaohu, China.

Lake Chaohu, which is a large, shallow, hypertrophic freshwater lake in southeastern China, has been experiencing lake-wide toxic Microcystis blooms in recent decades. To illuminate the relationships between microcystin (MC) production, the genotypic composition of the Microcystis community and environmental factors, water samples and associated environmental data were collected from June to October 2012 within Lake Chaohu. The Microcystis genotypes and MC concentrations were quantified using quantitative real-time PCR (qPCR) and HPLC, respectively. The results showed that the abundances of Microcystis genotypes and MC concentrations varied on spatial and temporal scales. Microcystis exists as a mixed population of toxic and non-toxic genotypes, and the proportion of toxic Microcystis genotypes ranged from 9.43% to 87.98%. Both Pearson correlation and stepwise multiple regressions demonstrated that throughout the entire lake, the abundances of total and toxic Microcystis and MC concentrations showed significant positive correlation with the total phosphorus and water temperature, suggesting that increases in temperature together with the phosphorus concentrations may promote more frequent toxic Microcystis blooms and higher concentrations of MC. Whereas, dissolved inorganic carbon (DIC) was negatively correlated with the abundances of total and toxic Microcystis and MC concentrations, indicating that rising DIC concentrations may suppress toxic Microcystis abundance and reduce the MC concentrations in the future. Therefore, our results highlight the fact that future eutrophication and global climate change can affect the dynamics of toxic Microcystis blooms and hence change the MC levels in freshwater.

Studies on the identification of constituents in ethanol extract of Radix Glycyrrhizae and their anticancer activity.

BACKGROUND: The main functions of Radix Glycyrrhizae include regulating middle warmer, moistening lung, relieving toxicity, harmonizing property of drugs which is a traditional Chinese medicine widely used in clinical settings. The objective of the paper is to isolate and identify the constituents in ethanol extract of Radix Glycyrrhizae, and to study their anticancer activity. MATERIALS AND METHODS: Column chromatography, ODS column chromatography, preparative thin layer chromatography and NMR spectroscopy techniques were used to isolate compounds from ethanol extract of Radix Glycyrrhizae; optical microscopy and flow cytometry were used to determine the anticancer effect of Radix Glycyrrhizae extract. RESULTS: Four compounds were isolated from the ethanol extract of Radix Glycyrrhizae, namely oleanolic acid, isoliquiritin, glycyrrhetinic acid and licochalcone A. Optical microscopic observation showed that the growth of gastric cancer cell line SGC-7901 was inhibited in the experimental groups, and apoptotic morphological changes were observed in adherent cells; flow cytometry with PI staining showed that Radix Glycyrrhizae extract could induce SGC-7901 cell apoptosis within a concentration range of 0.5-1.5 mg/mL, compared with the control group, the apoptosis was positively correlated with the drug concentration, which exhibited an apparent dose-dependence. CONCLUSION: We conclude Ethanol extract of Radix Glycyrrhizae has an anti-proliferative activity on SGC-7901 cells.

Study on the antibacterial activity of Bergenia purpurascens extract.

BACKGROUND: Bergenia purpurascens has tonic, haemostatic and anti-tussive actions. Anti-inflammatory and anti-bacterial activities of Bergenia purpurascens have not been reported so far. The objective of this paper is to provide experimental basis for the clinical application of Bergenia purpurascens through the pharmacodynamic study on its anti-inflammatory and anti-bacterial effects. METHODS: Experimental models of xylene-induced ear edema in mice, cotton pellet granuloma in rats, and acetic acid-induced peritoneal capillary permeability in mice were used to investigate the anti-inflammatory effect of Bergenia purpurascens; bacteriostatic and bactericidal effects of Bergenia purpurascens extract on Staphylococcus aureus (SA), methicillin-resistant Staphylococcus aureus (MRSA), and ß-lactamase positive Staphylococcus aureus (ESBLs-SA), were observed in vitro. RESULTS: The results show that Bergenia purpurascens extract could markedly inhibit xylene-induced mouse ear edema, cotton pellet granulation tissue hyperplasia, and increased capillary permeability. Bergenia purpurascens extract has an inhibitory effect on SA, MRSA and ESBLs-SA. CONCLUSION: We conclude that Bergenia purpurascens extract has certain anti-inflammatory and anti-bacterial effects.

[Preparation and pharmacokinetic evaluation of long-acting injectable oily suspensions for ophiopogonis radix polysaccharide MDG-1].

OBJECTIVE: To evaluate in vivo pharmacokinetics of Ophiopogonis Radix polysaccharide MDG-1 oily suspension injection prepared with different prescriptions in rats, and explore the feasibility of the long-acting drug delivery of MDG-1 Injection by using the oily suspension drug release system. METHOD: MDG-1 microparticles were prepared by the anti-solvent precipitation method. Their size and size distribution were characterized. Castor oil with a high viscosity or aluminum stearate were added into soybean oil with a low viscosity, in order to prepare oily media with different viscosities, detect their rheological properties and screen out superior prescriptions for in vivo evaluation. RESULT: The average size of microparticles was 21.81 microm, and the span between them was 2.63. The in vivo evaluation was conducted for prescriptions of mixed oil (soybean oil/castor oil, 2: 3) and soybean oils gelled by 2% and 4% aluminium stearate. Among them, the prescription of soybean gelled by 4% aluminium stearate could significantly reduce C(max) and prolong the apparent t1/2, with the MDG-1 release time of several days. CONCLUSION: It is feasible to achieve the long-acting MDG-1 drug delivery by using oily media with a high viscosity.

[Effect of light period length on the movement of exogenous phosphorus within simulative aqueous eco-systems].

Effect of light period length on the movement of exogenous phosphorus within aqueous eco-systems composed with water, Microcystis aeruginosa and sediments was studied by the method of phosphorus isotope tracer. Exogenous phosphorus was initially distributed rapidly in the systems in a mode of physical chemistry and then its movement was significantly influenced by the growth of M. aeruginosa. With the increasing of the light period length, the growth rate and cell density rose gradually and exogenous phosphorus level declined rapidly in the water. The light period length had nothing to do with the maximum of endocellular phosphorus per mg M. aeruginosa. After certain amounts of exogenous phosphorus were accumulated in M. aeruginosa, its growth didn't affect the amounts of endocellular phosphorus. When the light period length was long, the total amounts of exogenous phosphorus was high in M. aeruginosa. The exogenous phosphorus moved from water and cyanobacteria to sediment continuously until most of exogenous phosphorus transferred into sediment through the decline of M. aeruginosa.

[Effect of temperature on the translocation of exogenous 32P in water column, Microcystis aeruginosa and sediments].

Effect of temperature on the translocation of exogenous phosphorus in the simulative ecosystem composing of water, Microcystis aeruginosa and sediments was studied with the method of phosphorus isotope tracer. Exogenous 32P was initially distributed rapidly in the ecosystems in a mode of physical chemistry, irrespective of the influence of different temperature. Then, the translocation of 32P was significantly affected by the growth of M. aeruginosa in the ecosystem. Relatively high temperature was favorable to the growth of M. aeruginosa and accelerated the adsorption of exogenous phosphorus. The maximum concentration of exogenous endocellular phosphorus in M. aeruginosa was only related with the initial phosphorus concentration of water environment. The growth curve of M. aeruginosa contained short lag phase, 7-day log phase and decline phase but no obvious stationary phase at 25 degrees C. After certain amounts of exogenous phosphorus were accumulated in M. aeruginosa, its growth was independent of the amounts of endocellular phosphorus at 25 degrees C. The exogenous 32P moved from water and M. aeruginosa to sediment continuously and almost all of them transferred into sediment through the sedimentation of M. aeruginosa at the end of the experiment. The concentration of dissoluble exogenous 32P declined rapidly when water temperature was high and was less than 0.00716 mg.L-1 after 7 days.

Intracellular phosphorus metabolism of Microcystis aeruginosa under various redox potential in darkness.

Phosphorus metabolism of Microcystis aeruginosa was studied under gradient redox potential from 252 mV to -70 mV in darkness. The release of phosphorus occurred in all the treatments, and this process was accelerated in darkness when the redox potential was lowered. Low redox potential in darkness stimulated the accumulation of polyphosphate (PolyP) and the degradation of polyglucose. The synthesis of PolyP delayed the decrease of intracellular orthophosphate. The death of M. aeruginosa was slowered when the redox potential was low in darkness. The accumulation of PolyP under low redox potential in the dark was very important to M. aeruginosa for endurance through the unfavorable growth conditions for maintaining phosphorus concentration, energy storage, and other physiological functions. The ability to accumulate PolyP in the dark and negative redox potential may be of considerable advantage in the low-light, organically rich, and low-redox habitats.