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Effects of cultural conditions on denitrification by Pseudomonas stutzeri measured by Membrane Inlet Mass Spectrometry
Author(s) -
Firth J. R.,
Edwards C.
Publication year - 1999
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.1999.00820.x
Subject(s) - denitrification , pseudomonas stutzeri , chemistry , aerobic denitrification , nitrite , nitrous oxide , nitrate , environmental chemistry , nitrogen , nitrite reductase , pseudomonas chlororaphis , nitric oxide , inorganic chemistry , denitrifying bacteria , pseudomonas , organic chemistry , bacteria , biology , genetics
Denitrification is a globally important process leading to loss of fertiliser efficiency and the production of the greenhouse gas nitrous oxide and nitric oxide, an ozone depleter. Membrane inlet mass spectrometry (MIMS) was employed to study the effect of different variables on the process of denitrification by Pseudomonas stutzeri in a defined salts medium. MIMS was used for concomitant measurements of nitrous oxide, nitrogen and oxygen and showed that denitrification occurred in the presence of dissolved oxygen. A nitrate concentration of 15 mmol l −1 and a nitrite concentration of 5 mmol l −1 were found to be optimum for complete denitrification of nitrate or nitrite to nitrogen and varying these concentrations had a marked effect on the ratio of gaseous products released. Denitrification products were also dependant on pH with neutral or alkaline conditions being best for production of gaseous end products. Our results suggest that under nutrient rich conditions the most important factor in the regulation of denitrification by Ps. stutzeri is the amount of nitrite generated at the first enzymatic stage of the process. This appears to cause inhibition of the denitrification pathway above 5 mmol l −1 and at high enough concentrations (15 mmol l −1 ) restricts growth.