A rapid detection of multidrug-resistant Mycobacterium tuberculosis by a nitrate reductase assay on blood agar

The susceptibility of 49 Mycobacterium tuberculosis clinical isolates to isoniazid (INH) and rifampisin (RIF) (28 multi-drug resistant-tuberculosis samples) was determined by a nitrate reductase assay (NRA) on blood agar. Agreement between the NRA and other testing methods was found to be 93.8% for both INH and RIF. The sensitivity, specificity, positive predictive value and negative predictive value for INH were 92.8%, 94.2%, 86.6% and 97%, respectively. The sensitivity, specificity, positive predictive value and negative predictive value for RIF were 90.4%, 96.4%, 95% and 93.1%. In conclusion, we show here that blood agar can be used effectively for the NRA test.

Comparative evaluation under routine conditions of the nitrate reduction assay, the proportion assay and the MGIT 960 assay for drug susceptibility testing of clinical isolates of Mycobacterium tuberculosis

The performance of the nitrate reductase assay (NRA) was compared with the proportion method (PM) on Lowenstein-Jensen medium and the BACTEC MGIT960 assay under routine conditions using 160 clinical isolates of Mycobacterium tuberculosis with a high proportion of resistant strains. The mean time to obtain results was 8.8 days and the overall agreements between NRA and PM and NRA and M960 were 95% and 94%, respectively. NRA was easy to perform and represents a useful tool for the rapid screening of drug-resistant M. tuberculosis strains in low-resource countries.

Comparative evaluation of the microplate nitrate reductase assay and the rezasurin microtitre assay for the rapid detection of multidrug resistant Mycobacterium tuberculosis clinical isolates

The microplate nitrate reductase assay (MNRA) and the rezasurin microtitre assay (REMA) were used for the susceptibility testing of 73 clinical isolates and the results were compared with those that were obtained using the Bactec 460 TB and Bactec MGIT 960 systems. The REMA and the MNRA were performed in 96-well plates. For the REMA, the concentrations of isoniazid (INH) and rifampicin (RIF) ranged from 1.0-0.01 µg/mL and 2.0-0.03 µg/mL, respectively. For the MNRA, the INH concentration was between 1.0-0.03 µg/mL and the RIF concentration was between 2.0-0.06 µg/mL. For the MNRA, the sensitivity, specificity, positive predictive value, negative predictive value and INH/RIF agreement were 100/95.6, 97.6/100, 96.8/100, 100/98 and 98.6/98.6, respectively, and for the REMA, they were 100/91.3, 90.4/100, 88.5/100, 100/96.1 and 94.5/97.2, respectively. Our data suggest that these two rapid, low-cost methods may be inexpensive, alternative assays for the rapid detection of multidrug resistant tuberculosis in low-income countries.

Multi-isotopic and compositional exploration of factors controlling nitrate pollution

In Catalonia, according to the nitrate directive (91/676/EU), nine areas have been declared as vulnerable to nitrate pollution from agricultural sources (Decret 283/1998 and Decret 479/2004). Five of these areas have been studied coupling hydro chemical data with a multi-isotopic approach (Vitòria et al. 2005, Otero et al. 2007, Puig et al. 2007), in an ongoing research project looking for an integrated application of classical hydrochemistry data, with a comprehensive isotopic characterisation (δ15N and δ18O of dissolved nitrate, δ34S and δ18O of dissolved sulphate, δ13C of dissolved inorganic carbon, and δD and δ18O of water). Within this general frame, the contribution presented explores compositional ways of: (i) distinguish agrochemicals and manure N pollution, (ii) quantify natural attenuation of nitrate (denitrification), and identify possible controlling factors.To achieve this two-fold goal, the following techniques have been used. Separate biplots of each suite of data show that each studied region has a distinct δ34S and pH signatures, but they are homogeneous with regard to NO3- related variables. Also, the geochemical variables were projected onto the compositional directions associated with the possible denitrification reactions in each region. The resulting balances can be plot together with some isotopes, to assess their likelihood of occurrence

Nitrate Nitrogen in Iowa Rivers, 2001

Part of the Department of Natural Resources' Water Fact Sheet Series. This one is about Nitrate in Iowa's rivers and streams.

Methamphetamine Inhibitor: Calcium Nitrate– What You Need to Know, 2006

Iowa agriculture depends on anhydrous ammonia as a low-cost form of nitrogen fertilizer on 61 percent of Iowa’s 12.4 million acres of corn. Now we find a threat to that source of nutrient—the theft of anhydrous ammonia for use in making a powerful, illegal narcotic called methamphetamine. Naturally, the fertilizer industry is outraged by the illegal and illicit use of our products. We want to play a role in preventing abuse in the future. By raising awareness, knowing how to respond and using the Meth Inhibitor, fertilizer dealers can assist law enforcement in combating this illicit use of a product important to Iowa farmers.

Potential use of a chemical leaching reject from a kaolin industry as agricultural fertilizer

The industrial refining of kaolin involves the removal of iron oxides and hydroxides along with other impurities that cause discoloration of the final product and depreciate its commercial value, particularly undesirable if destined to the paper industry. The chemical leaching in the industrial processing requires treatments with sodium hyposulfite, metallic zinc, or sulfuric and phosphoric acids, in order to reduce, dissolve and remove ferruginous compounds. To mitigate the environmental impact, the acidic effluent from the leaching process must be neutralized, usually with calcium oxide. The resulting solid residue contains phosphorous, zinc, and calcium, among other essential nutrients for plant growth, suggesting its use as a macro and micronutrient source. Samples of such a solid industrial residue were used here to evaluate their potential as soil fertilizer in an incubation greenhouse experiment with two soil samples (clayey and medium-textured). The small pH shift generated by applying the residue to the soil was not a limiting factor for its use in agriculture. The evolution of the concentrations of exchangeable calcium, and phosphorous and zinc extractability by Mehlich-1 extractant during the incubation period confirms the potential use of this industrial residue as agricultural fertilizer.

Nitrate reductase and glutamine synthetase activity in coffee leaves during fruit development

Nitrate reductase is the first enzyme in the pathway of nitrate reduction by plants, followed by glutamine synthetase, which incorporates ammonia to glutamine. The purpose of this study was to evaluate the nitrate reductase and glutamine synthetase activity, total soluble protein content, N and Ni content in coffee leaves during fruit development under field conditions to establish new informations to help assess the N nutritional status and fertilizer management. The experimental design was in randomized complete blocks, arranged in a 3 x 6 factorial design, with five replications. The treatments consisted of 3 N rates (0 - control, 150 and 300 kg ha-1) and six evaluation periods (January, February, March, April, May, and June) in six-year-old coffee (Coffea arabica L.) plants of Catuaí Vermelho IAC 44 cv. The nitrate reductase and glutamine synthetase activities, leaf soluble protein, and N concentrations increased linearly with the N rates. During fruit development, the enzyme activity, leaf soluble protein and N content decreased, due to the leaf senescence process caused by nutrient mobilization to other organs, e.g, to the berries. Leaf Ni increased during fruit development. Beans and raisin-fruits of plants well-supplied with N had higher Ni contents. Enzyme activities, total leaf N and leaf soluble protein, evaluated during the green fruit stage in March, were significantly correlated with coffee yield. These variables can therefore be useful for an early assessment of the coffee N nutritional status as well as coffee yield and N fertilization management.

Nitrate reductase activity and spad readings in leaf tissues of guinea grass submitted to nitrogen and potassium rates

Nitrogen and K deficiency are among the most yield limiting factors in Brazilian pastures. The lack of these nutrients can hamper the chlorophyll biosynthesis and N content in plant tissues. A greenhouse experiment was carried out to evaluate the relationship among N and K concentrations, the indirect determination of chlorophyll content (SPAD readings), nitrate reductase activity (RNO3-) in newly expanded leaf lamina (NL) and the dry matter yield for plant tops of Mombaça grass (Panicum maximum Jacq.). A fractionated 5² factorial design was used, with 13 combinations of N and K rates in the nutrient solution. The experimental units were arranged in a randomized block design, with four replications. Plants were harvested twice. The first harvest occurred 36 days after seedling transplanting and the second 29 days after the first. Significance occurred for the interaction between the N and K rates to SPAD readings and to RNO3- assessment taken on the NL during the first growth. Besides, RNO3- and SPAD readings increased only with the NL N concentration, reaching the highest values of both variables up to about 25 g kg-1, but were ratively constant at higher leaf N. Significant relationships either between SPAD readings or RNO3- activity and shoot dry mass weight were also observed. The critical levels of N concentration in the NL were, respectively, 22 and 17g kg-1 in the first and second harvest. Thus, SPAD instrument and RNO3- assessment can be used as complementary tools to evaluate the N status in forage grass.