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.

EFFECTS OF CATECHOL AND P-BENZOQUINONE ON THE HYDROLYSIS OF UREA AND ENERGY BARRIERS OF UREASE ACTIVITY IN SOILS

1984 ◽  
Vol 64 (1) ◽  
pp. 51-60 ◽  
Author(s):  
J. S. TOMAR ◽  
A. F. MacKENZIE
Keyword(s):  
Activation Energy ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Key Words ◽  
Urease Activity ◽  
Urea Hydrolysis ◽  
Urease Inhibitors ◽  
Soil Urease ◽  
Hydrolysis Of ◽  
Hydrolysis Of Urea

The effects of the urease inhibitors, catechol and p-benzoquinone, and temperature on the hydrolysis of urea in five soils were investigated in a laboratory study. Urea hydrolysis decreased significantly with the amount of inhibitors applied and increased significantly with each 5 °C increase in temperature from 5 to 25 °C. The effectiveness of inhibitors generally decreased with increases in temperature from 5 to 25 °C. The correlation of hydrolysis of urea with organic matter contents of the soils was highly significant (r = 0.67** to 0.86**). Both catechol and p-benzoquinone tended to increase the energies and entropies of activation of soil urease and the effect was enhanced with a decrease in soil organic matter. It is suggested that an increase in the activation energy of the soil urease as a result of inhibitor use was related to an increase in the effectiveness of the inhibitor. Key words: Urease inhibitors, urea hydrolysis, energy of activation

Effects of toluene on microflora and hydrolysis of urea in a black spruce humus

1968 ◽  
Vol 14 (9) ◽  
pp. 999-1003 ◽  
Author(s):  
M. R. Roberge
Keyword(s):  
Picea Mariana ◽  
Phosphate Buffer ◽  
Urease Activity ◽  
Black Spruce ◽  
Urea Hydrolysis ◽  
Viable Bacteria ◽  
Bacteria And Fungi ◽  
Hydrolysis Of ◽  
Lower Production

The value of toluene as an antiseptic in determining the activity of urease in soil was studied in the surface organic horizon of a black spruce (Picea mariana Mill.) forest soil. Toluene was added in various amounts to layers of the humus suspended in water or in phosphate buffer, or sterilized by radiation, and incubated for various periods of time, followed by 8-h treatments with urea. Viable bacteria and fungi were detected by the dilution plate technique and the products of urea hydrolysis were determined by extraction and distillation. By increasing the amount of toluene or the time of contact of toluene with the humus, bacteria and fungi were reduced in number but not completely eliminated. The presence of urea resulted in a larger decrease of bacteria and fungi. With an increase in the amount of toluene, but not in the time of contact of toluene, a decrease was observed in urea hydrolysis. Some of the decrease was due to the inhibition of urease by toluene, and possibly some to the absorption of the products of urea hydrolysis and (or) to a lower production of urease by the surviving microorganisms. The last two possibilities render questionable the use of toluene in the determination of urease activity in soils.

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.

Urea hydrolysis and inorganic N in a Luvisol after application of fertiliser containing rare-earth elements

Soil Research ◽  
2003 ◽  
Vol 41 (4) ◽  
pp. 741 ◽  
Author(s):  
Xingkai Xu ◽  
Zijian Wang ◽  
Yuesi Wang ◽  
Kazuyuki Inubushi
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Substantial Reduction ◽  
Application Rate ◽  
Urea Hydrolysis ◽  
High Rate ◽  
Short Term ◽  
N Content ◽  
N Fertilisers ◽  
Hydrolysis Of

In recent decades, Chinese agriculturists have used rare-earth-containing fertilisers as basal fertilisers together with N fertilisers (e.g. urea). We studied urea hydrolysis and its hydrolysis products in a laboratory experiment using urea-N fertiliser with rare earths at rates from 0.5 to 50% (w/w). The results indicated that application of rare earths at a high rate could result in a short-term inhibition of urea hydrolysis and an increase in soil (NH4+ + NO3– + NO2–)-N content. When the application rate of rare earths was higher than 5% of the applied urea-N (corresponding to 10 mg/kg soil), soil exchangeable NH4+-N content increased significantly following the hydrolysis of the applied urea. Increasing the application rate of rare earths appeared to reduce the content of soil urea-derived (NO3– + NO2–)-N. A substantial reduction in soil pH was found immediately after application of rare earths and urea. We conclude that application of rare earths at >10 mg/kg may lead to a substantial increase in the content of urea-derived N in the soil, via the inhibition of urea hydrolysis and nitrification.

scholarly journals Towards By-Product Utilisation of Pea Hulls: Isolation and Quantification of Galacturonic Acid

Foods ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 203 ◽  
Author(s):  
Friederike Gutöhrlein ◽  
Stephan Drusch ◽  
Sebastian Schalow
Keyword(s):  
Galacturonic Acid ◽  
Ethylenediaminetetraacetic Acid ◽  
Raw Materials ◽  
Enzymatic Digestion ◽  
Raw Material ◽  
Trifluoracetic Acid ◽  
Complete Digestion ◽  
Digestion Methods ◽  
Fibre Matrix ◽  
By Products

In order to evaluate by-products from food processing as alternative raw materials for pectin extraction, their amount of galacturonic acid (GalA) has to be analysed as a marker for pectin content. In the present study, significant differences in GalA release using different digestion methods are shown for pea hulls, as an example of by-products with a high content of cellulose. Complete digestion of the fibre matrix was assumed for Saeman hydrolysis as a reference protocol. Significantly lower GalA release was achieved by a treatment with trifluoracetic acid (TFA). An alternative treatment with ethylenediaminetetraacetic acid (EDTA) at pH 11 followed by an enzymatic digestion at pH 4.5 using a combination of polygalacturonase (Vegazyme M) and cellulase (Celluclast 1.5L) resulted in a similar release of GalA compared to Seaman hydolysis. Pea hull samples, analysed by this alternative protocol, showed on average a GalA content of 11.2%. Therefore, pea hulls may serve as new raw material for pectin extraction.

FTIR as a rapid tool for monitoring molecular weight distribution during enzymatic protein hydrolysis of food processing by-products

2017 ◽  
Vol 9 (29) ◽  
pp. 4247-4254 ◽  
Author(s):  
Sileshi Gizachew Wubshet ◽  
Ingrid Måge ◽  
Ulrike Böcker ◽  
Diana Lindberg ◽  
Svein Halvor Knutsen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Food Processing ◽  
Protein Hydrolysis ◽  
Multivariate Approach ◽  
Hydrolysis Of ◽  
By Products ◽  
Rapid Tool

An FTIR-based multivariate approach is developed for monitoring molecular weight distribution during enzymatic protein hydrolysis of byproducts.

The release of soluble H-2 alloantigens during disaggregation of mouse embryo tissue by a chelating agent

Development ◽  
1966 ◽  
Vol 16 (3) ◽  
pp. 519-530
Author(s):  
Michael Edidin
Keyword(s):  
Molecular Weight ◽  
Ethylenediaminetetraacetic Acid ◽  
Divalent Cations ◽  
Weight Bearing ◽  
Chelating Agent ◽  
Cell Aggregation ◽  
Sponge Cell ◽  
Antigenic Sites ◽  
Dissociated Cells ◽  
Embryo Tissue

Treatment with chelating agents binding divalent cations has been found to effect the dissociation of a variety of tissues of both embryo and adult animals (reviewed in Steinberg, 1958). In the course of dissociation it appears that materials are released from cell surfaces which play a part in their specific adhesion, and which may be shown experimentally to promote selectively the re-aggregation of dissociated cells (Humphreys, 1963; Moscona, 1963). The extracted materials appear to be glycoprotein complexes (Humphreys, 1965), made up of fairly small subunits, estimated to be of 13000–20000 molecular weight (Margoliash et al. 1965). Units of about the same size appear to be the antigenic sites involved in the blocking of sponge cell aggregation by rabbit anti-sponge serum, specific for a given sponge species (MacLennan, 1963). I shall here present evidence that materials of similar molecular weight bearing immunological specificities of the H-2 alloantigen system are released from the tissues of certain mouse embryos during the course of their dissociation by the chelating agent Versene (ethylenediaminetetraacetic acid).

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