Author/Editor		Stres, Blaž; Čadež, Polona; Mahne, Ivan
Title		Vpliv kisika na vzpostavljanje denitrifikacije pri bakterijah: Pseudomonas stutzeri JM 300 in Flavobacterium ATCC 33514
Translated title		Effect of oxygen on denitrification in Pseudomonas stutzeri JM 300 and Flavobacterium ATCC 33514
Type		članek
Source		In: Bole-Hribovšek V, Ocepek M, Klun N, editors. Zbornik s programom 2. kongres slovenskih mikrobiologov z mednarodno udeležbo; 1998 sep 27-30; Portorož. Ljubljana: Slovensko mikrobiološko društvo,
Publication year		1998
Volume		str. 188-91
Language		slo
Abstract		Threshold values of oxygen concentration for synthesis and activity of nitrate and nitrite reductases were studied in two selected denitrifying bacteria Pseudumonas stutzeri JM 300 and Flavobacterium sp. ATCC 33514. Bacteria were grown in a complex medium supplemented with nitrate in a chemostat (D=0.08/h) under constant flushing with gaseous mixtures containing different concentrations of oxygen in nitrogen (0; 1,5; 2,5 in 21,0% 0 2). Consumption rates of nitrate and nitrite in the chemostat showed the combined effect of oxygen on activity as well as on the synthesis of the enzymes. Measurements of nitrate and nitrite consumption in a model with resting cells, which were previously grown under different oxygen concentrations, were used to evaluate the effect of oxygen on the synthesis of the reductive enzymes. Oxygen in concentrations higher than 2.5% in the gas mixture regulates denitrification in P. stutzeri by the inhibition of nitrate and nitrite reductases and by the repression of nitrite reductase. Synthesis of nitrate reductase is oxygen independent since periplasmic nitrate reductase appears under aerobic conditions. Threshold concentration of oxygen for pronounced repression of nitrate as well as nitrite reductase synthesis in Flavobacterium sp. is at 5%. 02 in a gas mixture. The activity of both enzymes is inhibited at lover oxygen concentrations.
Descriptors		FLAVOBACTERIUM PSEUDOMONAS NITRITE REDUCTASES NITRATE REDUCTASES OXYGEN NITRITES NITRATES BIOMASS