scholarly journals Culturable nitrogen-transforming bacteria from sequential sedimentation biofiltration systems and their potential for nutrient removal in urban polluted rivers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arnoldo Font Nájera ◽  
Liliana Serwecińska ◽  
Joanna Mankiewicz-Boczek
Keyword(s):  
Nutrient Removal ◽  
Nitrogen Assimilation ◽  
Nitrogen Transformation ◽  
Important Process ◽  
Bacterial Strains ◽  
Cell Biomass ◽  
Pseudomonas Mandelii ◽  
Polluted Rivers ◽  
Denitrification Process ◽  
Incorporated Nitrogen

AbstractNovel heterotrophic bacterial strains—Bzr02 and Str21, effective in nitrogen transformation, were isolated from sequential sedimentation-biofiltration systems (SSBSs). Bzr02, identified as Citrobacter freundii, removed up to 99.0% of N–NH4 and 70.2% of N–NO3, while Str21, identified as Pseudomonas mandelii, removed up to 98.9% of N–NH4 and 87.7% of N–NO3. The key functional genes napA/narG and hao were detected for Bzr02, confirming its ability to reduce nitrate to nitrite and remove hydroxylamine. Str21 was detected with the genes narG, nirS, norB and nosZ, confirming its potential for complete denitrification process. Nitrogen total balance experiments determined that Bzr02 and Str21 incorporated nitrogen into cell biomass (up to 94.7% and 74.7%, respectively), suggesting that nitrogen assimilation was also an important process occurring simultaneously with denitrification. Based on these results, both strains are suitable candidates for improving nutrient removal efficiencies in nature-based solutions such as SSBSs.

Comparison of nutrient removal efficiency between pre- and post-denitrification wastewater treatments

2006 ◽  
Vol 53 (9) ◽  
pp. 169-175 ◽  
Author(s):  
K. Hamada ◽  
T. Kuba ◽  
V. Torrico ◽  
M. Okazaki ◽  
T. Kusuda
Keyword(s):  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Biological Nutrient Removal ◽  
Biological Phosphorus Removal ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Nutrient Removal Efficiency ◽  
Polyphosphate Accumulating Organisms ◽  
Biological Phosphorus ◽  
Denitrification Process

A shortage of organic substances (COD) may cause problems for biological nutrient removal, that is, lower influent COD concentration leads to lower nutrient removal rates. Biological phosphorus removal and denitrification are reactions in which COD is indispensable. As for biological simultaneous nitrogen and phosphorus removal systems, a competition problem of COD utilisation between polyphosphate accumulating organisms (PAOs) and non-polyphosphate-accumulating denitrifiers is not avoided. From the viewpoint of effective utilisation of limited influent COD, denitrifying phosphorus-removing organisms (DN-PAOs) can be effective. In this study, DN-PAOs activities in modified UCT (pre-denitrification process) and DEPHANOX (post-denitrification ptocess) wastewater treatments were compared. In conclusion, the post-denitrification systems can use influent COD more effectively and have higher nutrient removal efficiencies than the conventional pre-denitrification systems.

scholarly journals Physical Environment and Symbiotic Nitrogen Fixation II. Root Temperature Effects on the Relative Nitrogen Assimilation Rate

1965 ◽  
Vol 18 (2) ◽  
pp. 295 ◽  
Author(s):  
AH Gibson
Keyword(s):  
Nitrogen Fixation ◽  
Physical Environment ◽  
Temperature Effects ◽  
Nitrogen Assimilation ◽  
Symbiotic Nitrogen Fixation ◽  
Trifolium Subterraneum ◽  
Bacterial Strains ◽  
Root Temperature ◽  
Relative Growth ◽  
Relative Growth Rates

Nitrogen fixation by six varieties of Trifolium subterraneum L., each inoculated with a number of strains of Rhizobium trifolii, was examined over a range of root temperatures. Significant differences in the rate of nodule establishment and early nitrogen fixation were found between varieties, and between bacterial strains. In order to minimize the effect of such differences, relative nitrogen assimilation rates (RN) and relative growth rates (R w) were used to compare the different legume-bacteria associations.

scholarly journals Exploration of endo-xylanase from novel strain of Bacillus velezensis AG20 isolated from the cave of Meghalaya

2020 ◽  
Author(s):  
Arabinda Ghosh ◽  
Shravanika Mahanta ◽  
Subhro Banerjee ◽  
Debabrat Baishya
Keyword(s):  
Ecological Niche ◽  
Orthogonal Design ◽  
Bacterial Strains ◽  
Bacillus Velezensis ◽  
Xylanase Production ◽  
Cell Biomass ◽  
Prime Objective ◽  
Hydrolysis Of ◽  
Industrial Demand

ABSTRACTCave sets the example of extreme ecological niche and habitat for diversified microorganisms. Present study involved in the isolation of endoxylanase producing novel strain Bacillus velezensis AG20 from the Krem Phyllut cave, Meghalaya, India. Culture dependent studies, molecular phylogentics, RNA secondary folding pattern based on 16S rDNA substantiated the identity of this novel strain. Bacillus velezensis AG20 revealed the superbug quality having resistance against various class of broad-spectrum antibiotics. Bacillus velezensis AG20 revealed biofilm formation over the cell surface in FESEM. Highest cell biomass and xylanase production supported in TB medium, further purified partially to 5.3 fold with 21% yield. Molecular weight of the purified xylanase found to be 45 kDa. Enzyme kinetics and pattern of hydrolysis revealed the evidence for the selection of linear birchwood xylan with Vmax = 21.0 ± 3.0 U/ml, Km = 1.25 mg/ml, Kcat = 1.75/s at optimum pH 7 and temperature 50°C also found significant statistically in Taguchi’s orthogonal design. Conversely, ruled out any exoacting activity against synthetic pNP-xylopyranoside substrate. Endo-xylanase isolated from Bacillus velezensis AG20 was moderately thermostable over temperatures 50 and 60°C. Time dependent hydrolysis of agro-waste sugar cane bagasse depicted the production of xylooligosaccharides (XOS) predominantly xylobiose, xylotriose and xylotetrose. Purified mixed XOS hold their prebiotic potential by promoting the growth of probiotics Bifidobacterium and Lactobacillus as well as high stability (~90%) against systemic fluids. Mixed XOS (300 μg/ml) displayed anti-proliferation activities by reducing the growth of HT-29 and Caco-2 cells significantly 90% and 75%, respectively, after 48 h.IMPORTANCEExtremophiles dwelling inside the caves have laden with the extraordinary capabilities of bioconversion by nature. The pristine ecological niche inside the cave, absence of proper light and air, supports the livelihood of novel microorganisms. In India, Meghalaya is hoisting longest caves in the East Khasi Hills, providing conducive environment for novel bacterial strains. With the prime objective of isolating novel bacterial strains that produce extracellular xylanase our studies have been carried out. Considering the present industrial demand for nutraceutical, prebiotics, anti-proliferating agents and biofuels by the conversion of lignocellulosic biomass (LCB), novel enzymes are required. Xylanases from bacterial origin play a significant role in conversion of LCB into oligosaccharides. Therefore, exploration and characterization of xylanase producing novel isolate from cave may pave the new arena for the production of prebiotic and anti-inflammatory oligosaccharides from agro-waste.

Evaluation of Sequencing Batch Biofilm Reactor for Biological Nutrient Removal from Simulated Domestic Wastewater

2012 ◽  
Vol 209-211 ◽  
pp. 2049-2052
Author(s):  
Chang Hang Wu ◽  
Wei Jun Zhang
Keyword(s):  
Removal Efficiency ◽  
Nutrient Removal ◽  
Domestic Wastewater ◽  
Biofilm Reactor ◽  
Biological Nutrient Removal ◽  
Sequencing Batch Biofilm Reactor ◽  
N Removal ◽  
Nitrification Process ◽  
Nitrification And Denitrification ◽  
Denitrification Process

A lab-scale sequencing batch biofilm reactor (SBBR) was developed to treat domestic wastewater. After one year’s operation, the results were obtained as follows: when the reaction carried out in 3 h, COD removal efficiency approached or reached the maximal value, up to 90%. The nitrification process of NH3-N needed 4 h, and NH3-N removal efficiency reached the maximal value. Moreover, according to the variation of TN , NO3--N and NO2--N concentration in the nitrification and denitrification process, when NH3-N degraded to zero or the minimal value, just two cycles ending, it means that the SBBR system completed the nitrification and denitrification process.

scholarly journals Intracellular competition for nitrogen controls dinoflagellate population density in corals

2020 ◽  
Vol 287 (1922) ◽  
pp. 20200049 ◽  
Author(s):  
Thomas Krueger ◽  
Noa Horwitz ◽  
Julia Bodin ◽  
Maria-Evangelia Giovani ◽  
Stéphane Escrig ◽  
...  
Keyword(s):  
Nitrogen Assimilation ◽  
Tissue Level ◽  
Feedback Mechanism ◽  
State Density ◽  
Nutrient Competition ◽  
Ambient Conditions ◽  
Stylophora Pistillata ◽  
Negative Feedback Mechanism ◽  
Cell Biomass ◽  
Host Nutrition

The density of dinoflagellate microalgae in the tissue of symbiotic corals is an important determinant for health and productivity of the coral animal. Yet, the specific mechanism for their regulation and the consequence for coral nutrition are insufficiently understood due to past methodological limitations to resolve the fine-scale metabolic consequences of fluctuating densities. Here, we characterized the physiological and nutritional consequences of symbiont density variations on the colony and tissue level in Stylophora pistillata from the Red Sea. Alterations in symbiont photophysiology maintained coral productivity and host nutrition across a broad range of symbiont densities. However, we demonstrate that density-dependent nutrient competition between individual symbiont cells, manifested as reduced nitrogen assimilation and cell biomass, probably creates the negative feedback mechanism for symbiont population growth that ultimately defines the steady-state density. Despite fundamental changes in symbiont nitrogen assimilation, we found no density-related metabolic optimum beyond which host nutrient assimilation or tissue biomass declined, indicating that host nutrient demand is sufficiently met across the typically observed range of symbiont densities under ambient conditions.

Modeling hydrolysis of slowly biodegradable organic compounds in biological nutrient removal activated sludge systems

2013 ◽  
Vol 67 (9) ◽  
pp. 2067-2074 ◽  
Author(s):  
J. Drewnowski ◽  
J. Makinia
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Biological Nutrient Removal ◽  
Biological Wastewater Treatment ◽  
Important Process ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting ◽  
Activated Sludge Systems

Hydrolysis is an important process in biological wastewater treatment and is known to be the rate-limiting step in organic carbon removal from municipal or industrial wastewater. The influence of the readily biodegradable chemical oxygen demand fraction in biological wastewater treatment systems has been extensively investigated, but little is known about the effects of slowly biodegradable substrate (XS) on denitrification and enhanced biological phosphorus removal. The biodegradation of XS is initiated by hydrolysis, which is an integral part of activated sludge models, such as the Activated Sludge Model no. 2d (ASM2d). This process is slower than heterotrophic growth and thus becomes the rate-limiting step for the biodegradation of organic compounds. The aim of this study was to evaluate different concepts of modeling the hydrolysis process using the original and modified version of ASM2d. Batch test results obtained at a large biological nutrient removal (BNR) plant in Gdansk (Poland) provided an experimental database for comparison of the two model predictions. Both models were compared in terms of their predictions for the most important process rates in BNR activated sludge systems. In comparison with the orginal ASM2d, the modified model had no or only minor effect on the predicted nitrate utilization rate, phosphate release rate and anoxic/aerobic phosphate uptake rate, but better predicted the oxygen uptake rate. The average ARDs (average relative deviations) were 19.0 and 29.3% (original ASM2d) vs. 13.4 and 20.4% (modified ASM2d), respectively, for the settled wastewater without pretreatment and after coagulation–flocculation.

Influence of temperature on microbial colonisation of clayey schist as a support media of a submerged filter for groundwater denitrification

2007 ◽  
Vol 55 (8-9) ◽  
pp. 165-172 ◽  
Author(s):  
A. De la Rúa ◽  
B. Rodelas ◽  
J. González-López ◽  
M.A. Gómez
Keyword(s):  
Biofilm Formation ◽  
Effect Of Temperature ◽  
Cold Environments ◽  
Pseudomonas Mandelii ◽  
Different Temperatures ◽  
Influence Of Temperature On ◽  
Denitrification Activity ◽  
Natural Microbiota ◽  
Denitrification Process ◽  
Made In

The effect of temperature on biofilm formation and denitrification activity was evaluated. Assays were made in a lab-scale submerged filter for the denitrification of polluted groundwater, with and without a previous inoculation. The inoculation was carried out with a selected strain of Pseudomonas mandelii. Different temperatures were tested: 5, 10, 20 and 30 °C. Biofilm observations were made, and monitoring of the denitrification capacity of the system was maintained during the experiment. Our results showed that both colonisation of the support material of the filter and biofilm maturity have a dependency with temperature, with an optimum temperature of 20 °C if the system was previously inoculated with the Pseudomonas mandelii strain. For a correct achievement of the denitrification process, a previous inoculation of the system is essential. Although the development of a biofilm from the natural microbiota present in the groundwater is possible, it is not capable to adequately denitrify polluted groundwater. In terms of the correct achievement of the denitrification process, temperature affects the operation of the system at cold environments, although the use of Pseudomonas mandelii strain A103 allows denitrification at 10–30 °C with very good results (above 90% removal), affecting only to the time needed for the stabilisation of the system.

Sign in / Sign up

Export Citation Format

Share Document