Nitrobacters

Nitrobacter, an aerobic bacterium, can materially depress pH by oxidizing nitrite (NO2 ) to nitrate (NOa ), in effect producing nitric acid. Acidity may increase until pH is between 3 and 5. Such bacteria require high concentrations of oxygen and cause problems only in oxygenated systems. 

Nitrite formulations are employed for both hot and cold water closed loops (and also occasionally for open cooling systems). Unfortunately, nitrite is easily oxidized to nitrate and is very susceptible to microbiological attack (by Nitrobacter agilis and other microorganisms). Nevertheless, it is a good low-cost passivating inhibitor. 

Before 1983, branched-chain sugars had not been found in bacterial polysaccharides, but there are now five examples belonging to this class. The LPS from Coxiella burned phase I contains both 6-deoxy-3-C-methyl-L-gulose (L-virenose) as pyranoside (12) and 3-C-(hydroxymethyl)-L-lyxose as furan-oside (13). Another 6-deoxy-3-C-methylhexose, having the manno configuration, is a component of the Nitrobacter hamburgiensis 0-antigen. ... 

Various plant species, ex. extracts, exudates, sugar- inhib d. Nitrosomonas, Nitrobacter 123-1 ... 

Purchase (153, 154), using root washings of H. filipendula, found no evidence of toxicity to Nitrobacter and Nitrosomonas. Since Nitrobacter is more sensitive to phosphorus deficiency than Nitrosomonas, and because phosphorus deficiency is sufficiently severe in some soils to restrict growth, its ability to compete for nitrogen is diminished. Inhibition was found in the root extract... 

The environmental impact of quinoline and its derivatives was considered by evaluating their toxicity on Nitrosomonas and Nitrobacter [377], The combination of wet oxidation and biological treatment was found to improve the impact by almost complete oxidations of the organics. 

Aerobic The reactions carried out by Nitrosomonas and Nitrobacter (reactions b and c, autotrophic respectively) are known as nitrification, while those carried out by Beggiatoa and Thiobacillus thiooxidans (reactions d and e, respectively) are examples of sulfur oxidation ... 

Autotrophic activity. Because of the low C N ratio and its declining value as carbonaceous residues are degraded there is substantial ammonification. With all mean treatment times greater than the doubling time of Nitrobacter sp. nitrification will occur provided that oxygen is not limiting. Smith and Evans (19) found that with DO levels above 15% of saturation, nitrification continued until the culture was limited by a fall in pH level. Up to 40% of the slurry ammonia was oxidised. The autotrophic activity never achieved steady state and cycled between periods of activity when the pH value was above about 5.5 and periods of inactivity when the pH value fell below 5.5. Complete nitrification of all ammonia only occurred if the pH value was controlled at about 7 by the addition of alkali. When the DO level was held within the range of 1 to 15% of saturation a system of simultaneous nitrification and denitrification was established. The reduction of nitrate allowed the pH value to remain above 6 and nitrification to continue. Thus more than 70% of the ammonia was oxidised. If the DO level was held below 0.1% of saturation, nitrification was inhibited (unpublished). 

In the proeess of generating biological growth you will need to watch the alkalinity of the soils, even when localized. In achieving nitrification, ammonia is consumed, but so is about 1.83 moles of Alkalinity as HC03-for every mole of Ammonia consumed by nitrosomanas and nitrobacter. 

Significantly more Nitrobacter inhabited the soil in plots of walnut mixed with European alder than in plots of walnut mixed with autumn-olive or walnut alone. Apparently juglone concentrations were not sufficient to inhibit populations of these nitrifying microorganisms. 

To gain more understanding of the European alder decline and because of our concern about the future growth of black walnut planted with nitrogen-fixing species, a study was initiated to measure soil juglone concentration and to estimate the number of Nitrobacter and Nltrosomonas bacteria in a black walnut plantation containing plots of black walnut alone and in mixture with European alder and autumn-olive. 

Soil samples were collected in mid-November at a distance of 0.9 m from each walnut tree at depths of 0-8, 8-16, and 16-30 cm for juglone estimates. Special effort was taken to avoid locating sample plots near dead or declining European alder trees. Another set of samples was collected at 0.9 m from walnut trees in the same plots at depths of 0-4, 4-8, 8-16, and 16-24 cm for Nitrobacter and Nitrosomonas counts. 

Although the number of Nitrosomonas bacteria was greater than the number of Nitrobacter in each treatment plots, only Nitrobacter differed significantly among treatments (Table II). Both Nitrosomonas and Nitrobacter counts decreased significantly with sampled depths. 

Table II. Mean Number of Nitrosomonas and Nitrobacter in Soil in...

One of the pitfalls of microbial sensors, viz. their low selectivity, can be overcome by combining cells with an immobilized enzyme. Thus, creatinine deaminase (CDA, EC 3.5.4.21) hydrolyses creatinine to N-methylhydantoin and ammonium ion, the ammonia produced being successively oxidized to nitrite and nitrate ion by nitrifying bacteria. These bacteria have not yet been characterized but are known to be a mixed culture of Nitrosomonas sp. and Nitrobacter sp. The reaction sequence involved is as follows ... 

Konig et al. [80-84] demonstrated that microbial sensors are suitable for the summary quantification of nitrifiable compounds (see also Sect. 3.3.1) as well as for the detection of nitrification inhibiting effects. Such biosensors, which contain a mixed population of the nitrifying bacteria Nitrosomonas sp. and Nitrobacter sp., exhibit a specific supplementary metabolic capacity. This enables the amperometric determination of ammonia according the following scheme of nitrification ... 

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