A review of the phosphorus removal of polyphosphate-accumulating organisms in natural and engineered systems.

Increasing eutrophication has led to a continuous deterioration of many aquatic ecosystems. Polyphosphate-accumulating organisms (PAOs) can provide insight into the human response to this challenge, as they initiate enhanced biological phosphorus removal (EBPR) through cyclical anaerobic phosphorus release and aerobic phosphorus uptake. Although the limiting environmental factors for PAO growth and phosphorus removal have been widely discussed, there remains a gap in the knowledge surrounding the differences in the type and phosphorus removal efficiencies of natural and engineered PAO systems. Furthermore, due to the limitations of PAOs in conventional wastewater treatment environments, there is an urgent need to find functional PAOs in extreme environments for better wastewater treatment. Therefore, it is necessary to explore the effects of extreme conditions on the phosphorus removal efficiency of PAOs as well as the types, sources, and characteristics of PAOs. In this paper, we summarize the response mechanisms of PAOs, denitrifying polyphosphate-accumulating organisms (D-PAOs), aerobic denitrifying polyphosphate-accumulating organisms (AD-PAOs), and sulfur-related PAOs (S-PAOs). The mechanism of nitrogen and phosphorus removal in PAOs is related to the coupling cycles of carbon, nitrogen, phosphorus, and sulfur. The genera of PAOs differ in natural and engineered systems, but PAOs have more diversity in aquatic environments and soils. Recent studies on the impact of several parameters (e.g., temperature, carbon source, pH, and dissolved oxygen) and extracellular polymer substances on the phosphorus removal efficiency of PAOs in natural and engineered systems are further discussed. Most of the PAOs screened under extreme conditions still had high phosphorus removal efficiencies (>80.0 %). These results provide a reference for searching for PAOs with different adaptations to achieve better wastewater treatment.

Hydroxyl/amino and Fe(III) co-grafted graphite carbon nitride for photocatalytic removal of volatile organic compounds.

Hydroxyl/amino and Fe(III) co-grafted graphite carbon nitride (CN) is fabricated via alkaline hydrothermal treatment and followed by an impregnation adsorption process. In this unique fabrication, hydroxyl and amino groups enriched on the surface play a vital role in improving the adsorption capacity for volatile organic compounds (VOCs), while the grafted amorphous Fe(III) clusters could dominantly regulate the path of molecular oxygen activation via photo-Fenton reaction, and change the selectivity of intermediate reactive oxygen species (ROS) with the assistant of the rich surficial hydroxyl groups. Meanwhile, both the grafted functional groups and Fe(III) clusters can serve as photogenerated charge acceptors for collaboratively accelerating carriers' separation. Besides, the Fe(III)-mediated interfacial charge transfer effect (IFCT) also could extend visible light absorption and boost carriers' generation. Benefiting from the virtues of the complementary and synergy of the grafted hydroxyl/amino and Fe(III), the dual-functionalized CN is qualified as an efficient photocatalyst for removal of VOCs, which exhibits 22 and 18 times isopropanol (IPA) adsorption capacity and CO2 production than of pristine CN during photocatalytic IPA removal, respectively. Moreover, this work provides a new strategy of surficial group-cluster bifunctionalization for systematically improving sustainable solar-to-chemical energy conversion towards VOCs mineralization.

[Effects and mechanisms of lotus leaf water extract on lipid metabolism of adult experimental obesity rats].

OBJECTIVE: To investigate the lipid metabolic effect and mechanism of water extract of lotus leaves(Traditional Chinese Medicine). METHODS: Isolated SD rat lipid tissues were suspended in organ baths containing Krebs solution, and the effect of lotus leaf water extract on free fatty acids (FFA) release was observed; The experimental obesity rat model was established by feeding them high glucose and fat diets, then the changes of body weight and blood lipid were measured in the model rats after intragastric administration with water extract of lotus leaves for four weeks, and the expressions of peroxisome proliferator-activated receptor gamma (PPAR-γ) and leptin were examined by RT-PCR and immunohistochemical. RESULTS: The ex vivo experiment showed that water extract of lotus leaves effectively promoted the FFA release from isolated lipid tissues. In vivo experiment, similarly to Orlistat, water extract of lotus leaves(60 mg/kg)markedly decreased the body weight and blood lipid of experimental obesity rats(P<0.05), and obviously reduced the expressions of PPAR-γ and leptin(P<0.05). CONCLUSIONS: Water extract of lotus leaves greatly improves the expression of PPAR-γ and leptin, which can promote the lipid mobilization and dissolution, reduce the body weight and blood lipid of adult rats with experimental obesity, therefore is expected to be developed into lipid-lowering diet pills.

Effects of estrogen and phytoestrogens on endometrial leakage in ovariectomized rats and the related mechanisms.

Phytoestrogens, a group of plant-derived non-steroidal compounds that can behave as estrogens by binding to estrogen receptors, have drawn great attention for their potentially beneficial effects on human health. However, there are few studies investigating the potential side effects of phytoestrogens on the reproductive system. The present study was to elucidate the effects of 17ß-estradiol (E2), progesterone (P4), and phytoestrogens genistein (Gen), resveratrol (Res), and phloretin (Phl) on eosinophilic infiltration of the ovariectomized rat uterus and endometrial vascular permeability, and to analyze the underlying mechanisms. The ovariectomized rats received daily subcutaneous injections of E2, E2+P4, P4, Gen, Res, Phl, or an equivalent volume of vehicle for 21 days, and sham-operated animals (Sham rats) were used as the controls. Hematoxylin-eosin staining revealed a marked increase in uterine eosinophilic infiltrations in ovariectomized rats treated with E2, E2+P4 or P4, which was associated with increased expression of vascular endothelial growth factor (VEGF), nuclear factor-κB (NF-κB), and tumor necrosis factor-α (TNF-α) proteins as determined by immunohistochemical and Western blot analysis. However, all three phytoestrogens had no markedly effect on the uterine eosinophilic infiltration and the expressions of VEGF, NF-κB, and TNF-α in the uterus of ovariectomized rats. Our data demonstrate that E2 alone or in combination with P4 increases uterine eosinophilic infiltration which is related with vascular hyperpermeability caused by VEGF, NF-κB and TNF-α, whereas phytoestrogens Gen, Res, and Phl, have no such an effect.

Inhibitory effects of genistein and resveratrol on guinea pig gallbladder contractility in vitro.

AIM: To observe and compare the effects of phytoestrogen genistein, resveratrol and 17beta-estradiol on the tonic contraction and the phasic contraction of isolated gallbladder muscle strips and to study the underlying mechanisms. METHODS: Isolated strips of gallbladder muscle from guinea pigs were suspended in organ baths containing Kreb's solution, and the contractilities of strips were measured before and after incubation with genistein, resveratrol and 17beta-estradiol respectively. RESULTS: Similar to 17beta-estradiol, genistein and resveratrol could dose-dependently inhibit the phasic contractile activities, they decreased the mean contractile amplitude and the contractile frequencies of gallbladder muscle strips, and also produced a marked reduction in resting tone. The blocker of estrogen receptor ICI 182780 failed to alter the inhibitory effects induced by genistein and resveratrol, but potassium bisperoxo (1, 10 phenanthroline) oxovanadate bpV (phen), a potent protein tyrosine phosphatase inhibitor, markedly attenuated the inhibitory effects induced by genistein and resveratrol. In calcium-free Kreb's solution containing 0.01 mmol/L egtazic acid (EGTA), genistein and resveratrol inhibited the first phasic contraction induced by acetylcholine (ACh), but did not affect the second contraction induced by CaCl(2). In addition, genistein, resveratrol and 17beta-estradiol also could reduce the contractile responses of ACh and KCl, and shift their cumulative concentration-response curves rightward. CONCLUSION: Phytoestrogen genistein and resveratrol can directly inhibit the contractile activity of isolated gallbladder muscle both at rest and in response to stimulation. The mechanisms responsible for the inhibitory effects probably due mainly to inhibition of tyrosine kinase, Ca(2+) influx through potential-dependent calcium channels (PDCs) and Ca(2+) release from sarcoplasmic reticulum (SR), but were not related to the estrogen receptors.

Effects of phytoestrogens and 17beta-estradiol on vasoconstriction elicited by reactive oxygen species.

To study the effects of different reactive oxygen species (ROS) on the resting tension of porcine coronary artery rings and to identify the effects of genistein (GEN), resveratrol (RES) and 17beta-estradiol (EST) on ROS-elicited vasoconstriction, porcine coronary rings were prepared and mounted in an organ bath and, after an equilibration period, the changes induced by the drugs were observed. Rings with intact endothelium showed an obvious but slow contraction after treatment with xanthine (100 microM)/xanthine oxidase (20 mU x mL(-1)) (X/XO) whereas endothelium-denuded rings showed no effects. H2O2 (200 microM) induced a fast and transient contraction in endothelium-denuded rings and failed to do so in intact-endothelium rings. Like superoxide dismutase (SOD, 200 U x mL(-1)), GEN (1 microM) and RES (1 microM) significantly inhibited contractile response evoked by X/XO, however in contrast to GEN and RES, EST (1 microM) had no obvious effect. GEN (30 microM) and RES (30 microM), like catalase (CAT, 800 U x mL(-1)), markedly attenuated the contraction elicited by H2O2. The results demonstrate that GEN and RES have distinct inhibitory effects on vasoconstriction induced by O2*- generated by X/XO and H2O2, and their actions are clearly greater than to that of EST.