Limits...
A determination and comparison of urease activity in feces and fresh manure from pig and cattle in relation to ammonia production and pH changes.

Dai X, Karring H - PLoS ONE (2014)

Bottom Line: The resulting Vmax value (mmol urea hydrolyzed per kg wet feces per min) was 2.06±0.08 mmol urea/kg/min and 0.80±0.04 mmol urea/kg/min for pig feces and cattle feces, respectively.Thus, our results reveal that both the Vmax and K'm values of the urease activity for pig feces are more than 2-fold higher than those for cattle feces.The initial velocities of TAN formation are 1.53 mM/min and 0.33 mM/min for pig and cattle manure, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Odense, Denmark.

ABSTRACT
Ammonia emission from animal production is a major environmental problem and has impacts on the animal health and working environment inside production houses. Ammonia is formed in manure by the enzymatic degradation of urinary urea and catalyzed by urease that is present in feces. We have determined and compared the urease activity in feces and manure (a urine and feces mixture) from pigs and cattle at 25°C by using Michaelis-Menten kinetics. To obtain accurate estimates of kinetic parameters Vmax and K'm, we used a 5 min reaction time to determine the initial reaction velocities based on total ammoniacal nitrogen (TAN) concentrations. The resulting Vmax value (mmol urea hydrolyzed per kg wet feces per min) was 2.06±0.08 mmol urea/kg/min and 0.80±0.04 mmol urea/kg/min for pig feces and cattle feces, respectively. The K'm values were 32.59±5.65 mmol urea/l and 15.43±2.94 mmol urea/l for pig feces and cattle feces, respectively. Thus, our results reveal that both the Vmax and K'm values of the urease activity for pig feces are more than 2-fold higher than those for cattle feces. The difference in urea hydrolysis rates between animal species is even more significant in fresh manure. The initial velocities of TAN formation are 1.53 mM/min and 0.33 mM/min for pig and cattle manure, respectively. Furthermore, our investigation shows that the maximum urease activity for pig feces occurs at approximately pH 7, and in cattle feces it is closer to pH 8, indicating that the predominant fecal ureolytic bacteria species differ between animal species. We believe that our study contributes to a better understanding of the urea hydrolysis process in manure and provides a basis for more accurate and animal-specific prediction models for urea hydrolysis rates and ammonia concentration in manures and thus can be used to predict ammonia volatilization rates from animal production.

Show MeSH

Related in: MedlinePlus

The effect of the pH on fecal urease activity.Urease activity at different pH values are presented as the rate of TAN formation (R. of formed TAN; panels A) and the relative R. of formed TAN compared with that of pig feces at pH 7 (panel B). The optimal pH for urea hydrolysis catalyzed by fecal urease is approximately pH 7 for pig feces and between pH 7 and 8 for cattle feces.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4232307&req=5

pone-0110402-g004: The effect of the pH on fecal urease activity.Urease activity at different pH values are presented as the rate of TAN formation (R. of formed TAN; panels A) and the relative R. of formed TAN compared with that of pig feces at pH 7 (panel B). The optimal pH for urea hydrolysis catalyzed by fecal urease is approximately pH 7 for pig feces and between pH 7 and 8 for cattle feces.

Mentions: The initial properties including the TKN, TAN, and UN concentrations, dry matter, and pH of feces, urine, and fresh manure from pigs and cattle were determined (Table 1). All the TKN values were higher for the pig samples than for the corresponding cattle samples. Thus, the highest TKN concentration was found in pig feces with a value of 578.8±1.2 mmol/kg and that of cattle feces was only 337.8±33.0 mmol/kg (p<0.05). The TKN values for pig and cattle urine were 350.2±2.1 mM and 261.3±0.9 mM, respectively. In addition, the TAN measurements for pig feces (39.6±4.6 mmol/kg) and urine (23.6±1.0 mM) were significantly higher than the values for cattle feces (21.2±0.4 mmol/kg) and urine (15.9±1.0 mM), respectively. In addition, the urea concentrations in the urine samples were evaluated by finding the UN values. The urea concentration of pig urine (99.2±2.5 mM) was significantly higher than it was in cattle urine (76.4±0.5 mM). The dry matter of pig feces (15.32±0.09%) was approximately 4% higher than it was for cattle feces (11.44±0.22%), and the pH values of both pig feces (pH 6.89±0.01) and urine (pH 7.69±0.03) were lower than the corresponding values for cattle (pH 7.02±0.02 and 8.55±0.02, respectively) (p<0.05). With the exception of the TAN concentration in pig manure, all the values measured in fresh manure samples (combined feces and urine samples) were consistent with the expected values based on those determined for the separate feces and urine samples and their ratios in the combined feces and urine samples. The relatively high TAN concentration in pig manure (87.2±1.6 mM; Table 1) is most likely caused by the significantly faster formation of NH3 in manure from pigs than from cattle when feces and urine are mixed (Figure 3). Therefore, the initial TAN concentrations used to determine the TAN formed in the manure reactions (Figures 1, 3, 4, and Figures S2 and S3) were calculated by adding the proportions of TAN originating from pure feces and urine (or urea stock solution) (Table 1).


A determination and comparison of urease activity in feces and fresh manure from pig and cattle in relation to ammonia production and pH changes.

Dai X, Karring H - PLoS ONE (2014)

The effect of the pH on fecal urease activity.Urease activity at different pH values are presented as the rate of TAN formation (R. of formed TAN; panels A) and the relative R. of formed TAN compared with that of pig feces at pH 7 (panel B). The optimal pH for urea hydrolysis catalyzed by fecal urease is approximately pH 7 for pig feces and between pH 7 and 8 for cattle feces.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232307&req=5

pone-0110402-g004: The effect of the pH on fecal urease activity.Urease activity at different pH values are presented as the rate of TAN formation (R. of formed TAN; panels A) and the relative R. of formed TAN compared with that of pig feces at pH 7 (panel B). The optimal pH for urea hydrolysis catalyzed by fecal urease is approximately pH 7 for pig feces and between pH 7 and 8 for cattle feces.
Mentions: The initial properties including the TKN, TAN, and UN concentrations, dry matter, and pH of feces, urine, and fresh manure from pigs and cattle were determined (Table 1). All the TKN values were higher for the pig samples than for the corresponding cattle samples. Thus, the highest TKN concentration was found in pig feces with a value of 578.8±1.2 mmol/kg and that of cattle feces was only 337.8±33.0 mmol/kg (p<0.05). The TKN values for pig and cattle urine were 350.2±2.1 mM and 261.3±0.9 mM, respectively. In addition, the TAN measurements for pig feces (39.6±4.6 mmol/kg) and urine (23.6±1.0 mM) were significantly higher than the values for cattle feces (21.2±0.4 mmol/kg) and urine (15.9±1.0 mM), respectively. In addition, the urea concentrations in the urine samples were evaluated by finding the UN values. The urea concentration of pig urine (99.2±2.5 mM) was significantly higher than it was in cattle urine (76.4±0.5 mM). The dry matter of pig feces (15.32±0.09%) was approximately 4% higher than it was for cattle feces (11.44±0.22%), and the pH values of both pig feces (pH 6.89±0.01) and urine (pH 7.69±0.03) were lower than the corresponding values for cattle (pH 7.02±0.02 and 8.55±0.02, respectively) (p<0.05). With the exception of the TAN concentration in pig manure, all the values measured in fresh manure samples (combined feces and urine samples) were consistent with the expected values based on those determined for the separate feces and urine samples and their ratios in the combined feces and urine samples. The relatively high TAN concentration in pig manure (87.2±1.6 mM; Table 1) is most likely caused by the significantly faster formation of NH3 in manure from pigs than from cattle when feces and urine are mixed (Figure 3). Therefore, the initial TAN concentrations used to determine the TAN formed in the manure reactions (Figures 1, 3, 4, and Figures S2 and S3) were calculated by adding the proportions of TAN originating from pure feces and urine (or urea stock solution) (Table 1).

Bottom Line: The resulting Vmax value (mmol urea hydrolyzed per kg wet feces per min) was 2.06±0.08 mmol urea/kg/min and 0.80±0.04 mmol urea/kg/min for pig feces and cattle feces, respectively.Thus, our results reveal that both the Vmax and K'm values of the urease activity for pig feces are more than 2-fold higher than those for cattle feces.The initial velocities of TAN formation are 1.53 mM/min and 0.33 mM/min for pig and cattle manure, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Odense, Denmark.

ABSTRACT
Ammonia emission from animal production is a major environmental problem and has impacts on the animal health and working environment inside production houses. Ammonia is formed in manure by the enzymatic degradation of urinary urea and catalyzed by urease that is present in feces. We have determined and compared the urease activity in feces and manure (a urine and feces mixture) from pigs and cattle at 25°C by using Michaelis-Menten kinetics. To obtain accurate estimates of kinetic parameters Vmax and K'm, we used a 5 min reaction time to determine the initial reaction velocities based on total ammoniacal nitrogen (TAN) concentrations. The resulting Vmax value (mmol urea hydrolyzed per kg wet feces per min) was 2.06±0.08 mmol urea/kg/min and 0.80±0.04 mmol urea/kg/min for pig feces and cattle feces, respectively. The K'm values were 32.59±5.65 mmol urea/l and 15.43±2.94 mmol urea/l for pig feces and cattle feces, respectively. Thus, our results reveal that both the Vmax and K'm values of the urease activity for pig feces are more than 2-fold higher than those for cattle feces. The difference in urea hydrolysis rates between animal species is even more significant in fresh manure. The initial velocities of TAN formation are 1.53 mM/min and 0.33 mM/min for pig and cattle manure, respectively. Furthermore, our investigation shows that the maximum urease activity for pig feces occurs at approximately pH 7, and in cattle feces it is closer to pH 8, indicating that the predominant fecal ureolytic bacteria species differ between animal species. We believe that our study contributes to a better understanding of the urea hydrolysis process in manure and provides a basis for more accurate and animal-specific prediction models for urea hydrolysis rates and ammonia concentration in manures and thus can be used to predict ammonia volatilization rates from animal production.

Show MeSH
Related in: MedlinePlus