Phenol-hypochlorite reaction for determination of ammonia

Analytical Chemistry (Impact Factor: 5.83). 04/2002; 39(8). DOI: 10.1021/ac60252a045
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    ABSTRACT: The sunflower is an oilseed crop with potential for different uses, from food and biofuel production. Water shortage and poor rainfall distribution have attracted the attention of researchers, to identify genotypes with genotypic characteristics to tolerate this abiotic stress. Thus this work aimed to select sunflower genotypes differing in drought tolerance, based on growth and N, P and K leaf contents. Were evaluated 27 sunflower genotypes grown at 50% field conditions during 20 days. The results allow to conclude that AG AG-963, AG-967 and BRS 322 genotypes were the most drought-tolerant, while the genotypes IAC-Iarama, Catissol, IAC-Uruguai, BRS G27, TC Rola and AG 962 were the most drought-sensitive. N, P and K leaf contents were not related to water stress tolerance. NPK contents did not show relationship with the characters of tolerance or sensitivity to stress.
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    ABSTRACT: Background Ureolytic activity of rumen bacteria leads to rapid urea conversion to ammonia in the rumen of dairy cows, resulting possible toxicity, excessive ammonia excretion to the environment, and poor nitrogen utilization. The present study investigated immunization of dairy cows against urease in the rumen as an approach to mitigate bacterial ureolytic activity therein. Results Most alpha subunit of rumen urease (UreC) proteins shared very similar amino acid sequences, which were also highly similar to that of H. pylori. Anti-urease titers in the serum and the saliva of the immunized cows were evaluated following repeated immunization with the UreC of H. pylori as the vaccine. After the fourth booster, the vaccinated cows had a significantly reduced urease activity (by 17%) in the rumen than the control cows that were mock immunized cows. The anti-urease antibody significantly reduced ureolysis and corresponding ammonia formation in rumen fluid in vitro. Western blotting revealed that the H. pylori UreC had high immunological homology with the UreC from rumen bacteria. Conclusions Vaccine developed based on UreC of H. pylori can be a useful approach to decrease bacterial ureolysis in the rumen. Electronic supplementary material The online version of this article (doi:10.1186/s12917-015-0409-6) contains supplementary material, which is available to authorized users.
    BMC Veterinary Research 12/2015; 11(1). DOI:10.1186/s12917-015-0409-6 · 1.74 Impact Factor
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    ABSTRACT: Bacillus licheniformis TISTR 1010 was identified as a glutamic acid-independent producer of poly-γ-glutamic acid (γ-PGA) in a newly modified B medium in a shake flask culture. The fed-batch production of γ-PGA by this strain was optimized through simultaneously and continuously feeding glucose and NH4Cl with manual and pH-stat based feeding methods in a 7-L stirred fermenter. Using the optimized operation, the dissolved oxygen concentration, the pH, the glucose concentration and NH4Cl concentration could be stably controlled to extend the γ-PGA production phase and eliminate the hydrolysis of γ-PGA. As a result, the γ-PGA concentration and productivity reached levels of 27.5±0.2 g L−1 and 0.286±0.059 g L−1 h−1, respectively. These values of final concentration and productivity were 5-fold and 3-fold of those obtained without the optimization.
    Biochemical Engineering Journal 04/2015; DOI:10.1016/j.bej.2015.04.007 · 2.37 Impact Factor