Nitrate reducing bacteria

Only a few studies have been undertaken on the role of bacteria in nitrosation at neutral pH in the Intestinal tract itself. Hashimoto al. (9 ) demonstrated that by changing the equilibrium between different species of microorganisms in the gut, (by administration of antibiotics and inoculation with nitrate-reducing strains) dimethylnitrosamine (NDMA) accumulated in the stomach and cecum of rats fed dlmethylamine (DMA) and nitrate. The authors describe only one experimental group, however, and the mechanism of NDMA formation is not clear. 

Slreploinyces species Chitin or cellulose utilization Denitrifying or nitrate-reducing bacteria... 

Li H., Duncan C., Townend J., Smith L., Kilham K., Johnston P., Dykhuizen R., Kelly D., Golden M., Benjamin N. and Leifert C. (1997). Nitrate reducing bacteria on rat tongues . Appl Environ Microbiol, 63, 924-930. 

Li H., Duncan C., Golden M. and Leifert C. (1999). Identification of nitrate reducing bacteria from the oral cavity of rats and pigs , in Wilson W.S., Ball A.S. and Hinton R.H., Managing Risks of Nitrates to Humans and the Environment, Royal Society of Chemistry, Cambridge, 259-268. 

The nitrite test can be used to detect the presence of nitrate-reducing bacteria in the urine (such as E. coli). The leukocyte esterase test is a rapid dipstick test to detect pyuria. 

Other organisms and routes of xylene metabolism are also known. Azoarcus sp. strain Td-15 was the only one of eight toluene-degrading, nitrate-reducing bacteria isolated by Fries et al. (1994) capable of metabolizing w-xylene, but the... 

Similar mechanisms operate in the action of nitrate reductase and nitrite reductase. Both of these substances are produced from ammonia by oxidation. Plants and soil bacteria can reduce these compounds to provide ammonia for metabolism. The common agricultural fertilizer ammonium nitrate, NH4NO3, provides reduced nitrogen for plant growth directly, and by providing a substrate for nitrate reduction. NADH or NADPH is the electron donor for nitrate reductase, depending on the organism. 

When all of the dissolved oxygen is consumed, anaerobic organisms take over. Initially, nitrate-reducing bacteria are favoured... 

Lopez-Gutierrez, J. C., Henry, S., HaUet, S., Martin-Laurent, F., Catroux, G., and Phihppot, L. (2004). Quantification of a novel group of nitrate-reducing bacteria in the environment by realtime PCR.J. Microbiol. Meth. 57, 399—407. 

BenzM., Brune A., and Schink B. (1998) Anaerobic and aerobic oxidation of ferrous iron at neutral pH by chemoheterotrophic nitrate-reducing bacteria. Arch. Microbiol. 169, 159-165. 

Nitrate and NO2 reduction are rather widespread in SO reducers (Keith and Herbert, 1983 McCready et al., 1983 Mitchell et al., 1986 Maumetal., 1997 Seitz and Cypionka, 1986), and in some cases NOj" is preferred over SO (Seitz and Cypionka, 1986). The bisulfite reductase enzyme in SO reducers displays some activity toward NO2, which partially explains the ubiquity of NO2 reduction. However, it appears that specific NO2 reductases are also present (Liu and Peck Jr., 1981). Unlike denitrifying bacteria that reduce NOj" to N2, the end product of NOj" reduction in SO reducers is NH4 (Widdel and... 

Nijburg J. W. and Laanbroek H. J. (1997) The influence of Glyceria maxima and nitrate input on the composition and nitrate metabolism of the dissimilatory nitrate-reducing bacteria community. FEMSMicrobiol. Ecol. 22, 57-63. 

Ogilvie B. G., Rutter M., and Nedwell D. B. (1997b) Selection by temperature of nitrate-reducing bacteria from estuarine sediments species composition and competition for nitrate. FEMS Microbiol. Ecol. 23, 11 —22. 

Straub K. L. and Buchholz-Cleven B. E. E. (1998) Enumeration and detection of anaerobic ferrous iron-oxidizing, nitrate-reducing bacteria from diverse European sediments. Appl. Environ. Microbiol. 64, 4846-4856. 

Table 3 lists the predominant microorganisms in both DNA and RNA profiles for the control batch at T=0. Both DNA and RNA analysis of the nitrate microcosm at T=3 days showed substantial shifts in community composition (Table 4), with Arcobacter sp. dominating in both cases. Arcobacter sp. are known as nitrate reducers since they play a role in nitrogen fixation, so this shift is consistent with sediment conditions. A couple of additional nitrate-reducing bacteria. Pseudomonas sp. and Nisaea denitrificans, were also identified. 

Nitrite is irritating to eyes, skin, and respiratory tract. Exposure to sufficiently high concentrations can cause death. Many animal species lack the nitrate-reducing bacteria and therefore do not provide a good model for methemoglobin formation. 

The brown color of old meat is the result of oxidation of blood and is objectionable to many consumers. Nitrites and nitrates are added to food to retard this oxidation and also to prevent growth of botulism bacteria. Nitrate ions, N03, are reduced to N02 ions, which are then converted to NO. This in turn reacts with the brown oxidized form of the heme in blood. This reaction keeps meat red longer. Controversy has arisen, however, concerning the possibility that nitrites combine with amines under the acidic conditions in the stomach to produce carcinogenic nitrosoamines. 

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