The Possible Roles of Escherichia coli in the Nitrogen Cycle

Autor: Maryam Taabodi, Salina Parveen, Thomas P. Oscar, Fawzy Hashem, Eric B. May
Rok vydání: 2019
Předmět:
Zdroj: International Journal of Environmental Research. 13:597-602
ISSN: 2008-2304
1735-6865
Popis: This study was designed to determine the response of Escherichia coli to three different nutrient sources. In this study, E. coli was exposed to concentrations of ammonia as ammonium chloride and nitrate as sodium nitrate at 0.5, 1.0 and 2.0 mg/L; and reagent grade urea at 10, 20 and 30 µg/L using bacterial concentrations of 10−1, 10−2 and 10−3 per ml. Cultures were incubated for 24 h at 37 °C. Samples were analyzed using a LACHET™ (800 Series) for ammonia-N, Nitrate-N and Urea-N which was converted to molar concentrations. Growth rates for E. coli were determined using serial dilutions, incubated on 3 M™ Petrifilm™ for 24 h at 37 °C with colony counts taken. The results showed that E. coli was able to utilize both ammonia and nitrate, with ammonium utilization significantly greater than nitrate. Ammonium utilization was directly proportional to concentration of ammonium chloride added and to some degree, the initial number of bacteria exposed. Nitrate utilization occurred at all concentrations and dilutions when compared with control concentrations and corresponded with concentrations of nitrate, but there was very little difference between bacterial dilutions. Urea production did occur but was unaffected by either concentration of urea or bacteria dilution. Positive growth rates were seen with ammonium with increasing growth rates as ammonium chloride concentrations were increased. Urea appeared to cause a slight decrease in growth, but nitrate was inconclusive with regard to growth.
Databáze: OpenAIRE
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