scholarly journals Kinetic Determination of Urease Activity in Fresh Pig Feces and Slurry and the Effect on Ammonia Production at Different Conditions

2019 ◽  
Vol 11 (22) ◽  
pp. 6396 ◽  
Author(s):  
Chaozhi Hao ◽  
Yuepeng Pan ◽  
Zhongyi Zhang ◽  
Yang Zeng
Keyword(s):  
Urease Activity ◽  
Early Stage ◽  
Formation Rate ◽  
Urea Hydrolysis ◽  
Ammonia Production ◽  
Mixing Rate ◽  
Pollution Problem ◽  
Environmental Pollution Problem ◽  
Fresh Feces ◽  
Urease Production

Ammonia (NH3) emissions have become a serious environmental pollution problem, and livestock production is an important source of NH3 emissions, especially pig farming. The origin of NH3 release is the hydrolysis of urea in urine that is catalyzed by urease present in feces. This research determined the urease activity in fresh feces by Michaelis–Menten kinetics and then compared the process of urea hydrolysis and ammonia production in fresh slurry. For feces, the kinetic parameters Vmax and K’m were calculated by determining the concentration of ammonium in initial 5 minutes in closed vessels, and the resulting Vmax and K’m were 26.9 ± 1.2 mmol·[urea]·kg−1·min−1 and 99.7 ± 3.5 mmol·[urea]·l−1, respectively. In fresh slurry, the rate of urea hydrolysis determined directly was higher than the ammonium formation rate in the early stage (0–8 h) and was accompanied by a rapid rise in pH. In addition, we further explored the effects of temperature, pH, and mixing rate on urease activity within different periods (0–5 min, 5 min–2 h and 2 h–8 h). Our observations show that the optimal urease activity occurred at 35 °C, pH 6.71, and 821.83 rpm of stirring, indicating that microbial species and communities associated with urease production are affected by environmental conditions.

scholarly journals Urease testing and yeast taxonomy

1987 ◽  
Vol 33 (5) ◽  
pp. 396-404 ◽  
Author(s):  
J. Leland Booth ◽  
H. S. Vishniac
Keyword(s):  
Urease Activity ◽  
Ethylenediaminetetraacetic Acid ◽  
Chelating Agent ◽  
Maximal Activity ◽  
Urea Hydrolysis ◽  
Basidiomycetous Yeasts ◽  
Urease Production ◽  
Ascomycetous Yeasts ◽  
Hydrolysis Of ◽  
By Products

When urease production was assayed by the hydrolysis of [14C]urea, all basidiomycetous yeasts tested, including the Cryptococcus vishniacii complex (previously reported urease negative), produced significant amounts of 14CO2. The Schizosaccharo-mycetaceae were the only urease-positive ascomycetous yeasts tested. Yarrowia lipolytica was urease negative. The stoichiometry of [14C]urea hydrolysis paralleled by Roberts' rapid urea hydrolysis (RUH) test indicated that causes of anomalous results in conventional urease testing include acidification and alkalinization of the test medium by products of endogenous metabolism and autolysis rather than urease activity. Anomalous results also occurred when cells were grown on media containing the chelating agent ethylenediaminetetraacetic acid (EDTA) prior to RUH. The addition of EDTA to a complex natural medium inhibited urease production in all yeasts reportedly growing at 35 °C (and all other yeasts tested), except Filobasidiella (Cr.) neoformans var. neoformans (NIH 12). The RUH test could differentiate at the varietal level: Fil. (Cr.) neoformans var. neoformans was about 10 times more resistant to EDTA in media used for the growth of cells prior to RUH testing than was Fil. neoformans var. bacillispora (Cr. neoformans var. gattii) (NIH 191). Urease production by Fil. neoformans var. bacillispora was specifically restored to half maximal activity by the addition of 22 μM Ni+2 (as NiCl2) to a growth medium containing 0.100 mM EDTA.

scholarly journals Process Engineering of the Acetone-Ethanol-Butanol (ABE) Fermentation in a Linear and Feedback Loop Cascade of Continuous Stirred Tank Reactors: Experiments, Modeling and Optimization

Fuels ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 108-129
Author(s):  
Katja Karstens ◽  
Sergej Trippel ◽  
Peter Götz
Keyword(s):  
Feedback Loop ◽  
Early Stage ◽  
Formation Rate ◽  
Abe Fermentation ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Second Phase ◽  
Stirred Tank Reactors ◽  
Continuous Stirred Tank ◽  
Continuous Stirred Tank Reactors

The production of butanol, acetone and ethanol by Clostridium acetobutylicum is a biphasic fermentation process. In the first phase the carbohydrate substrate is metabolized to acetic and butyric acid, in the following second phase the product spectrum is shifted towards the economically interesting solvents. Here we present a cascade of six continuous stirred tank reactors (CCSTR), which allows performing the time dependent metabolic phases of an acetone-butanol-ethanol (ABE) batch fermentation in a spatial domain. Experimental data of steady states under four operating conditions—with variations of the pH in the first bioreactor between 4.3 and 5.6 as well as the total dilution rate between 0.042 h−1 and 0.092 h−1—were used to optimize and validate a corresponding mathematical model. Beyond a residence time distribution representation and substrate, biomass and product kinetics this model also includes the differentiation of cells between the metabolic states. Model simulations predict a final product concentration of 8.2 g butanol L−1 and a productivity of 0.75 g butanol L−1 h−1 in the CCSTR operated at pHbr1 of 4.3 and D = 0.092 h−1, while 31% of the cells are differentiated to the solventogenic state. Aiming at an enrichment of solvent-producing cells, a feedback loop was introduced into the cascade, sending cells from a later state of the process (bioreactor 4) back to an early stage of the process (bioreactor 2). In agreement with the experimental observations, the model accurately predicted an increase in butanol formation rate in bioreactor stages 2 and 3, resulting in an overall butanol productivity of 0.76 g L−1 h−1 for the feedback loop cascade. The here presented CCSTR and the validated model will serve to investigate further ABE fermentation strategies for a controlled metabolic switch.

scholarly journals Green innovation, government incentive and enterprise performance are explored from the perspective of game

2021 ◽  
Vol 275 ◽  
pp. 02006
Author(s):  
Xiaohui Ren
Keyword(s):  
Game Theory ◽  
Rapid Development ◽  
Enterprise Performance ◽  
Green Innovation ◽  
Green Development ◽  
Pollution Problem ◽  
Environmental Pollution Problem ◽  
And Performance ◽  
The Relationship

The rapid development of economy brings serious environmental pollution problem. Green innovation, as the connection point between government environmental regulation measures and sustainable green development of enterprises, has become one of the important choices for the transformation and development of enterprises. Based on the classic model of “prisoner’s dilemma” in game theory, this paper deeply analyzes the relationship between green innovation and performance. It is found that it is easy to get into trouble if only relying on the spontaneous green innovation within the enterprise. Applying appropriate pressure outside the enterprise can promote the change of green innovation and bring long-term benefits to the enterprise.

The Analysis of the Current Situation and Countermeasures of New Energy Vehicles

2014 ◽  
Vol 686 ◽  
pp. 639-642
Author(s):  
Wei Li ◽  
Ming Yuan Ma
Keyword(s):  
Social Capital ◽  
Management Mechanism ◽  
Pollution Problem ◽  
The Social ◽  
New Energy ◽  
Environmental Pollution Problem ◽  
The Government ◽  
New Energy Vehicle ◽  
Battery Technology ◽  
New Energy Vehicles

With pm2.5 and environmental pollution problem of urban smog, energy conservation and environmental protection has become an important subject in the current car development, so the new energy vehicles get more and more favor from the government and enterprises. But the new energy vehicles’ market share in our country is still small and the technology is not mature. This paper summarizes the experience and lessons in the development of new energy vehicles at home and abroad, and then based on which analyses the reasons that restrict the development of the new energy vehicles, finally puts forward the countermeasures of new energy vehicles development from the government's macro policy, battery technology, management mechanism, public participation and so on. In addition, it also puts forward a new opinion that encourages and guides the social capital to participate in the operation of the new energy vehicle infrastructure construction and operation, then provides a model for our country’s new energy vehicles future development.

Morphological Evolution of Low-Grade Silica Fume at Elevated Temperature

2017 ◽  
Vol 36 (6) ◽  
pp. 607-613 ◽  
Author(s):  
Junhong Chen ◽  
Tong Li ◽  
Xiaoping Li ◽  
Kuo-Chih Chou ◽  
Xinmei Hou
Keyword(s):  
Elevated Temperature ◽  
Silica Fume ◽  
Room Temperature ◽  
Morphological Evolution ◽  
Hydroxyl Groups ◽  
Morphological Development ◽  
Low Grade ◽  
Structural Development ◽  
Pollution Problem ◽  
Environmental Pollution Problem

AbstractTo solve the environmental pollution problem caused by low-grade silica fume (SiO2, < 86 mass%) and further expand its application field, the morphological development of low-grade silica fume from room temperature to 900 °C in air was investigated using TG-DTA, SEM and TEM techniques. The structural development of silica fume was further analyzed using FT-IR and Raman spectrum. The results show that silica fume contains many defects of broken bands such as Si-O or ≡Si at room temperature. When exposed to the moister or water, the broken bonds tend to react with water and result in the formation of Si-OH and adjacent hydroxyl groups of Si-OH•OH-Si. At elevated temperature up to 900 °C, the structure of silica fume becomes compact due to the reconstruction of the broken bonds caused by the dehydration reaction.

scholarly journals Antioxidant Molecules from Plant Waste: Extraction Techniques and Biological Properties

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1566
Author(s):  
Cynthia E. Lizárraga-Velázquez ◽  
Nayely Leyva-López ◽  
Crisantema Hernández ◽  
Erick Paul Gutiérrez-Grijalva ◽  
Jesús A. Salazar-Leyva ◽  
...  
Keyword(s):  
Antibacterial Properties ◽  
Biological Properties ◽  
Antioxidant Compounds ◽  
Green Technologies ◽  
Advantages And Disadvantages ◽  
Pollution Problem ◽  
Plant Waste ◽  
Potential Applications ◽  
Environmental Pollution Problem ◽  
Pharmaceutical Industries

The fruit, vegetable, legume, and cereal industries generate many wastes, representing an environmental pollution problem. However, these wastes are a rich source of antioxidant molecules such as terpenes, phenolic compounds, phytosterols, and bioactive peptides with potential applications mainly in the food and pharmaceutical industries, and they exhibit multiple biological properties including antidiabetic, anti-obesity, antihypertensive, anticancer, and antibacterial properties. The aforementioned has increased studies on the recovery of antioxidant compounds using green technologies to value plant waste, since they represent more efficient and sustainable processes. In this review, the main antioxidant molecules from plants are briefly described and the advantages and disadvantages of the use of conventional and green extraction technologies used for the recovery and optimization of the yield of antioxidant naturals are detailed; finally, recent studies on biological properties of antioxidant molecules extracted from plant waste are presented here.

Experimental Study on Sulfuric Acid Leaching Behavior of Chromite with Different Temperature

2011 ◽  
Vol 361-363 ◽  
pp. 628-631 ◽  
Author(s):  
Cheng Jun Liu ◽  
Jie Qi ◽  
Mao Fa Jiang
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Raw Material ◽  
Leaching Rate ◽  
Sulfuric Acid Leaching ◽  
Leaching Process ◽  
Pollution Problem ◽  
Environmental Pollution Problem ◽  
Leaching Solution ◽  
Leaching Residue

Utilizing Pakistan chromite as raw material, the rapid leaching of chromium and iron could be realized by the sulfuric acid leaching process on the condition of atmospheric pressure and the addition of oxidant A. And the leaching rate of chromium and iron would be 98.5% and 71.9%, respectively. The sulfuric acid leaching processes with different temperature were systematically studied by chemical analysis and phase analysis. The results showed that, with the increase of reaction temperature, the leaching rate of chromium would increase gradually, but the leaching rate of iron increased at first and then decreases and reached its maximum at 140°C. When the temperature > 160°C, the phases of the leaching residue were magnesium iron silicate and a few of silica, no chromohercynite, chrompicotite and magnesioferrite existed in the chromite. The leaching solution of sulfuric acid leaching process could be used for preparing the basic chrome sulfate, and there is no Cr6+ in the leaching residue and solution. The results would provide theoretical guidance for solving environmental pollution problem of Cr6+ in traditional chromate production process.

Urease activity related to the growth and differentiation of swarmer cells of Proteus mirabilis

1987 ◽  
Vol 33 (4) ◽  
pp. 300-303 ◽  
Author(s):  
Tianru Jin ◽  
R. G. E. Murray
Keyword(s):  
Proteus Mirabilis ◽  
Urease Activity ◽  
Casein Hydrolysate ◽  
Brain Heart Infusion ◽  
Liquid Media ◽  
Whole Cells ◽  
Maximum Proportion ◽  
The Media ◽  
Urease Production ◽  
Different Strains

Urease activity was measured using whole cells of both long (swarming) and short (nonswarming) populations of Proteus mirabilis from casein hydrolysate agar (CHA) and broth (CHB) cultures, and from brain heart infusion broth (BHIB) cultures. Urease is a constitutive enzyme for both long and short cells, but its activity was tremendously increased when urea was incorporated into the media. Urease production was also affected by culture age and media used. Before exponential phase, urease activity was very low, and it increased to its highest point after about 4 h in BHIB and 8 h in both CHA and CHB cultures at 37 °C. Long cells had higher urease activity than did short cells when grown on CHA, and was also expressed by two different strains cultured in BHIB. Strain PM23, in BHIB, was able to form long cells (swarming cells) to a maximum proportion after about 4 h, but strain IM47 could not differentiate in any of the liquid media. The former had more urease when swarming differentiation was initiated. PM23 grew relatively faster than IM47 when the former began to differentiate, but this fast growth could not be observed when nutrient broth or minimal medium was used. These observations suggest that long or swarming cells are "faster growing" rather than "nongrowing bactera."

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