Ammonia-oxidizing bacteria with different sensitivities to (NH4)2SO4 in activated sludges

• Published in: Water research (Oxford) 1994, Vol.28 (7), p.1523-1532
• Main Authors: SUWA, Y, IMAMURA, Y, SUZUKI, T, TASHIRO, T, URUSHIGAWA, Y
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biological treatment of waters; Biotechnology; Environment and pollution; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/0043-1354(94)90218-6

Ammonia oxidizing bacteria were enumerated in activated sludge samples from sewage works, nightsoil treatment plants and laboratory organic and inorganic sludges by the Most Probable Number method (MPN) using 2 media. MPN estimates obtained with the medium containing 37.9 mM ammonium sulphate were lower than with the medium containing 0.76 mM ammonium sulphate, except for the inorganic laboratory sludges where both media provided almost the same MPN estimates. This suggested that ammonia oxidizers in the inorganic sludge were insensitive to ammonium sulphate. Ten isolates obtained from 4 sludge samples were identified as Nitrosomonas species and were cultivated at various concentrations of ammonium sulphate, as were 4 ammonia oxidizers obtained from ATCC. Isolates obtained from sludge sensitive to ammonium sulphate did not grow on media containing higher ammonium sulphate concentrations whereas the remaining isolates and ATCC strains did. The Monod equation described the relationship between ammonium sulphate concentration and nitrite production rates for insensitive strains. The Haldane equation, which described substrate inhibition kinetics, was more suitable for the sensitive strains. Ammonium sulphate sensitive strains had a growth advantage in low ammonium sulphate concentrations. Insensitive strains had the advantage in higher ammonium sulphate concentrations. As all ATCC strains exhibited the characteristics of insensitive organisms, they may not always be appropriate in explaining ammonia oxidation in natural environments and wastewater treatment processes. There are 41 references.