Microbial denitrification is a major pathway for nitrogen removal from water bodies. However, denitrification is often difficult to continue when there is a lack of microbially available organic matter in the water body to serve as electron donors. In recent years, studies have shown that some denitrifying bacteria can directly utilize photoelectrons generated by sunlight-excited semiconductor minerals or natural organic matter for denitrification without the need for bioavailable organic matter as electron donors. This process is defined as microbial photoelectrotrophic denitrification. The discovery of microbial photoelectrotrophic denitrification phenomenon reshapes the previous knowledge about the chemoheterotrophic mode of denitrifying bacteria and broadens the pathway of nitrogen removal by the new photoelectrotrophic metabolism, which is of great significance to our understanding and exploration of sunlight-driven nitrogen cycling process. In this paper, we comprehensively sort out the existing research reports in the field of microbial photoelectrotrophic denitrification, systematically summarize the principle and the current research progress of microbial photoelectrotrophic denitrification, deeply analyze the problems and challenges faced by this technology, and make an outlook on the future research directions and application prospects of this technology, providing a reference for the further research and application of this technology.
Denitrification/physiology* ; Nitrogen/isolation & purification* ; Bacteria/metabolism* ; Sunlight ; Phototrophic Processes

The biological nitrogen removal technology utilizing heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria has shown effectiveness in wastewater treatment. However, the nitrogen removal efficiency of HN-AD bacteria significantly decreases as the salinity increases. To tackle the challenge of treating high-salt and high-nitrogen wastewater, we isolated a moderately halophilic HN-AD strain 5505 from a salt lake in Xinjiang. The strain was identified based on morphological, physiological, and biochemical characteristics and the 16S rRNA gene sequence. Single-factor experiments were carried out with NH₄⁺-N, NO₃^--N, and NO₂^--N as sole or mixed nitrogen sources to study the nitrifying effect, denitrifying effect, and nitrogen metabolism pathway of the strain. The strain was identified as Halomonas sp.. It can grow in the presence of 1%-25% (W/V) NaCl and exhibited efficient nitrogen removal ability in the presence of 3%-8% NaCl. At the optimal NaCl concentration (8%), the strain showed the NH₄⁺-N, NO₃^--N and NO₂^--N removal rates of 100.0%, 94.11% and 74.43%, respectively. Strain 5505 removed inorganic nitrogen mainly by assimilation, which accounted for over 62.68% of total nitrogen removal. In the presence of mixed nitrogen sources, strain 5505 showed a preference for utilizing ammonia, with a potential HN-AD pathway of NH₄⁺→NH₂OH→NO₂^-→NO₃^-→NO₂^-→NO/N₂O/N₂. The findings provide efficient salt-tolerant bacterial resources, enhance our understanding of biological nitrogen removal, and contribute to the nitrogen removal efficiency improvement in the treatment of high-salt and high-nitrogen wastewater.
Halomonas/classification* ; Nitrogen/isolation & purification* ; Denitrification ; Nitrification ; Wastewater/microbiology* ; Aerobiosis ; Biodegradation, Environmental ; Salinity

The aim of this study was to establish a novel technology using microalgae for NO₃⁻ removal from high concentration wastewater and conversion to algal proteins. The effects of cultivation modes and illumination modes on the biomass yield, NO₃⁻ assimilation rate and algal protein yield were first investigated in shaking flasks for mixotrophic cultivation of Chlorella pyrenoidosa, and subsequently the scale-up verification in 5-L photo fermenter was successfully conducted. Fed-batch cultivation without medium recycling was the best cultivation mode in shaking flask system, in which the highest biomass yield (35.95 g/L), the average NO₃⁻ assimilation rate (2.06 g/(L·d)) and algal protein content (up to 42.44% of dry weight) were achieved. By using a staged increase of light intensity as illumination modes, the specific growth rate of cells could be significantly promoted to the highest (0.65 d⁻¹). After a 128-hour continuous cultivation in a 5-L photo fermenter, the highest biomass yield and the average NO₃⁻ assimilation rate were reached to 66.22 g/L and 4.38 g/(L·d) respectively, with the highest algal protein content at 47.13% of dry weight. Our study could provide a photo fermentation technology of microalgae for highly efficient treatment of waste industrial nitric acid and/or high concentration nitrate wastewater. This microalgae-based bioconversion process could coproduce protein-rich microalgal biomass, which facilitates the resource utilization of these type wastewater by trash-to-treasure conversion.
Algal Proteins ; biosynthesis ; Biomass ; Chlorella ; Nitrates ; isolation & purification ; metabolism ; Nitrogen ; metabolism ; Waste Water ; chemistry ; Water Purification ; methods

In this study, SD rats were orally administrated with oteracil potassium (300 mg . kg-1 . d-1 ) to prepare the hyperuricemia model, and divided into normal, model, Allopurinol, LE high dosage, middle dosage and low dose (200, 100, 50 mg . kg-1 . d-1) groups. The rats were orally administrated with test drugs 1 hour later after being orally administrated with Oteracil potassium. After 7 days, serum uric acid, serum creatinine, uric acid and expression of relevant transporters in kidney were tested to study the regulatory effect of leonurus extracts on serum uric acid, renal function and relevant transporters in kidney of rats with hyperuricemia. Compared with the model group, the leonurus extract group could significantly down-regulate serum uric acid and creatinine levels of rats with hyperuricemia, and increase the urine uric acid level. Meanwhile, leonurus extracts could notably down-regulate the mRNA expressions of urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9), up-regulate the mRNA expressions of organic cation transportanter (OCT) and Carnitine transporter (OCTN) and promote the excretion of uric acid of kidney.
Allopurinol ; pharmacology ; Animals ; Blood Urea Nitrogen ; Creatinine ; blood ; Disease Models, Animal ; Down-Regulation ; Gene Expression Regulation ; drug effects ; Hyperuricemia ; blood ; drug therapy ; Kidney ; drug effects ; Leonurus ; chemistry ; Male ; Organic Anion Transporters ; genetics ; Oxonic Acid ; administration & dosage ; Plant Extracts ; isolation & purification ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Specific Pathogen-Free Organisms ; Up-Regulation ; Uric Acid ; blood

OBJECTIVETo investigate whether total triterpene acids (TTAs), isolated from Cornus Fructus, attenuates renal function by reducing oxidative stress and down-regulating the expression of transforming growth factor β1 (TGF-β1).

METHODSDiabetes was induced by an injection of streptozotocin (40 mg/kg intravenously). Thirty rats were randomly divided into three groups: control group, diabetic model group and TTAs treatment group (50 mg/kg, intragastrically) administrated for 8 weeks from 5th to 12th week. All rats were anaesthetized and then were killed to remove kidneys. The renal function and redox enzyme system parameters were tested. Glomerular morphology was observed by a light microscopy. Immunohistochemistry and Western blot assays were employed to determine the protein levels of TGF-β1.

RESULTSTTAs attenuated the levels of urinary protein, serum creatinine and blood urea nitrogen, although it did not significantly reduce the level of glucose. In addition, TTAs decreased the malondialdehyde while increased superoxide dismutase, catalase and glutathione peroxide activities in diabetic rats. The renal pathological changes in TTAs treatment group were ameliorated. Furthermore, TTAs also ameliorated the expression of TGF-β1.

CONCLUSIONTTAs improved renal function via reducing oxidative stress and down-regulation the expression of TGF-β1 in diabetic rats.

Animals ; Blood Glucose ; metabolism ; Blood Urea Nitrogen ; Blotting, Western ; Body Weight ; drug effects ; Catalase ; metabolism ; Cornus ; chemistry ; Creatinine ; metabolism ; Diabetes Mellitus, Experimental ; blood ; drug therapy ; pathology ; physiopathology ; Disease Progression ; Glutathione Peroxidase ; metabolism ; Hypertrophy ; Kidney ; drug effects ; pathology ; physiopathology ; Kidney Function Tests ; Male ; Malondialdehyde ; metabolism ; Rats, Sprague-Dawley ; Streptozocin ; Superoxide Dismutase ; metabolism ; Transforming Growth Factor beta1 ; metabolism ; Triterpenes ; isolation & purification ; pharmacology ; therapeutic use

Nitrogen source is one of the important factors that affect the microalgae growth and lipid accumulation. We studied the effects of various nitrogen sources (i.e. NaNO3, CO(NH2)2, NH4Cl and CH3COONH4) and amount on the growth density, lipid yield, and eicosapentaenoic acid (EPA) content of Nannochloropsis oculata by single factor experimental method. The results show that N. oculata preferred NH4+ as nitrogen source rather than NO3- and CO(NH2)2. NH4+ could promote the growth and lipid accumulation of N. oculata. With the increase of nitrogen concentration, the biomass and the content of polyunsaturated fatty acid (PUFA) increased, but the content of lipid decreased. CH3COONH4 was the most suitable for growth, accumulation of lipid and EPA of N. oculata among the four investigated nitrogen sources. The optimal concentration was 5.29 mmol/L.
Eicosapentaenoic Acid ; metabolism ; Lipids ; biosynthesis ; isolation & purification ; Microalgae ; growth & development ; metabolism ; Nitrogen ; analysis ; metabolism ; Stramenopiles ; growth & development ; metabolism

Field experiments were conducted in Shangluo pharmaceutical base in Shaanxi province to study the effect of nitrogen, phosphorus and potassium in different fertilization levels on Platycodon grandiflorum soil microorganism and activities of soil enzyme, using three-factor D-saturation optimal design with random block design. The results showed that N0P2K2, N2P2K0, N3P1K3 and N3P3K1 increased the amount of bacteria in 0-20 cm of soil compared with N0P0K0 by 144.34%, 39.25%, 37.17%, 53.58%, respectively. The amount of bacteria in 2040 cm of soil of N3P1K3 increased by 163.77%, N0P0K3 increased the amount of soil actinomycetes significantly by 192.11%, while other treatments had no significant effect. N2P0K2 and N3P1K3 increased the amounts of fungus significantly in 0-20 cm of soil compared with N0P0K0, increased by 35.27% and 92.21%, respectively. N3P0K0 increased the amounts of fungus significantly in 20-40 cm of soil by 165.35%, while other treatments had no significant effect. All treatments decrease soil catalase activity significantly in 0-20 cm of soil except for N2P0K2, and while N2P2K0 and NPK increased catalase activity significantly in 2040 cm of soil. Fertilization regime increased invertase activity significantly in 2040 cm of soil, and decreased phosphatase activity inordinately in 0-20 cm of soil, while increased phosphatase activity in 2040 cm of soil other than N1P3K3. N3P0K0, N0P0K3, N2P0K2, N2P2K0 and NPK increased soil urease activity significantly in 0-20 cm of soil compared with N0P0K0 by 18.22%, 14.87%,17.84%, 27.88%, 24.54%, respectively. Fertilization regime increased soil urease activity significantly in 2040 cm of soil other than N0P2K2.
Bacteria ; enzymology ; growth & development ; isolation & purification ; metabolism ; Bacterial Proteins ; analysis ; metabolism ; Catalase ; analysis ; metabolism ; Fertilizers ; analysis ; Fungal Proteins ; analysis ; metabolism ; Fungi ; enzymology ; growth & development ; isolation & purification ; metabolism ; Nitrogen ; metabolism ; Phosphoric Monoester Hydrolases ; analysis ; metabolism ; Phosphorus ; metabolism ; Potassium ; metabolism ; Soil ; chemistry ; Soil Microbiology ; Urease ; analysis ; metabolism

Protective effects of two different extracts of TSCA (total saponins from Cicer arietinum) were studied on kidney of T2DM rats. The diabetic model group was established with high calorie feeding and small dose injection of streptozotocin (STZ, 45 mg x kg(-1)). DM rats were randomly assigned to model group (feed with propylene glycol 1 mL/100 g), TSCA high dose group (300 mg x kg(-1)), TSCA low dose group (100 mg x kg(-1)) and normal control group (feed with propylene glycol 1 mL/100 g). After four weeks treatment with TSCA I and II, the levels of FPG FIns, BUN, Scr, ATII, ET-1, TXB2 and 6-keto-PGF1alpha in blood and the activities of SOD, GSH-PX and MDA in kidney were analyzed by biochemical methods. After four weeks treatment with TSCA II, the levels of FPG FIns, BUN, Scr, ATII and ET-1 were reduced significantly; and the ratios of TXB2 to 6-keto-PGF1alpha and SOD were effectively alleviated in TSCA II group. While there is no significant change on FPG and BUN in comparison to the rats treated with TSCA I, Scr, ATII, ET-I, GSH-PX and SOD were alleviated. The results suggest that TSCA II could be used to reduce FPG and FIns. According to the result of vasoactive substances index, TSCA II is more effective than TSCA I on renal protection of DM rats.
6-Ketoprostaglandin F1 alpha ; blood ; Angiotensin II ; blood ; Animals ; Blood Glucose ; metabolism ; Blood Urea Nitrogen ; Cicer ; chemistry ; Creatinine ; blood ; Diabetes Mellitus, Experimental ; blood ; metabolism ; Diabetes Mellitus, Type 2 ; blood ; metabolism ; Endothelin-1 ; blood ; Glutathione Peroxidase ; metabolism ; Hypoglycemic Agents ; isolation & purification ; pharmacology ; Insulin ; blood ; Kidney ; metabolism ; Male ; Malondialdehyde ; metabolism ; Plants, Medicinal ; chemistry ; Random Allocation ; Rats ; Rats, Wistar ; Saponins ; isolation & purification ; pharmacology ; Superoxide Dismutase ; metabolism ; Thromboxane B2 ; blood

Anaerobic ammonium oxidation (Anammox) process is a high-rate nitrogen removal technology that has been applied in sludge dewatering effluents treatment with nitrogen removal rate as high as 9.5 kg/(m x d). However, due to the slow growth rate of the autotrophic Anammox bacteria and the susceptivity to environmental conditions, the start-up of Anammox process is very long; the operation is unstable; and the nitrogen removal from organic-containing and/or toxicant-containing ammonium-rich wastewaters using Anammox process becomes difficult. Thus, the application of this high-rate process is significantly limited. In this paper, a newly-developed Anammox process with sequential biocatalyst (Anammox biomass) addition was established based on the procedure in fermentation engineering. We introduced the Anammox process with sequential biocatalyst addition on start-up, stable operation and the treatment of organic-containing and toxicant-containing ammonium-rich wastewaters. Results show that supplementing high-activity Anammox biomass into reactors will increase the amount of as well as the ratio of Anammox bacteria. Thus, the innovative Anammox process with sequential biocatalyst addition not only accelerates the start-up course, but also enhances the stability of Anammox process. Furthermore, it overcomes the drawbacks of wastewaters containing high organic content and toxic substances. Therefore, the application of Anammox process may be further enlarged.
Bacteria, Anaerobic ; enzymology ; growth & development ; metabolism ; Biocatalysis ; Biomass ; Bioreactors ; microbiology ; Enzymes ; chemistry ; Nitrogen ; isolation & purification ; metabolism ; Oxidation-Reduction ; Quaternary Ammonium Compounds ; isolation & purification ; metabolism ; Waste Disposal, Fluid ; methods

OBJECTIVETo develop a HPLC method for the quantitative determination of four nitrogenous compounds in Pinellia peda-tisecta.

METHODThe determination was carried out on Diamonsil-C18 column(4. 6 mm x 250 mm, 5 microm) eluted with acetonitrile-water-triethylamine in gradient elution acetonitrile-water- triethylamine. The mobile phase was a flow rate of 1.0 mL x min(-1) and detection wavelength as 254 nm.

RESULTThe linear ranges of trigonelline, thymine, amidopurine and hypoxanthine were 0.2 - 1.0 microg (r = 0.999 6), 2.6-13 microg (r = 0.999 8), 0.55-2.75 microg (r = 0.999 9), 0.65-3.25 microg (r = 0.999 8), respectively. The average recoveries of trigonelline, thymine, amidopurine and hypoxanthine were 100.6%, 99.89%,100.5% and 100.0% respectively, and the RSD of the above four compounds were 2.4%, 0.20%, 1.1%, 1.4%, respectively.

CONCLUSIONThis method is reliable, accurate and specific. It can be used for quality control of the tube of P. peda-tisecta.

Chromatography, High Pressure Liquid ; methods ; Drugs, Chinese Herbal ; analysis ; isolation & purification ; Nitrogen Compounds ; analysis ; isolation & purification ; Pinellia ; chemistry