Characterization of the Nitrite-Oxidizing System in Nitrobacter
Nitrobacter X 14 was isolated from soil of the old Botanical Garden in Hamburg. It is a facultative lithotrophic nitrite-oxidizing bacterium. As well as Nitrobacter agilis (Smith and Hoare, 1968; Bock, 1976) Nitrobacter X 14 was able to grow mixotrophically and heterotrophically. In contrast to other strains of Nitrobacter the doubling time of autotrophically grown cells was not 13 h but 40 h. After nitrite consumption the cell yield with 3 mg protein/1 was lower than in Nitrobacter agilis (5.5 mg protein/1). Under mixotrophic conditions with nitrite, pyruvate, and yeast extract-peptone (py—ni cells) growth was much better. The doubling time was 10– 11 h and the cell yield amounted to 17 mg protein/1 when the nitrite was consumed. When Nitrobacter X 14 was grown heterotrophically with pyruvate as carbon and energy source and yeast extract-peptone to meet nitrogen requirements (y—py cells) cells doubled within 15– 20h, when grown with pyruvate and casamino acids (cas—py cells) the doubling time increased to more than 20 h. Compared to Thiobacillus intermedius (London and Rittenberg, 1966) Nitrobacter X 14 should be regarded as an organism highly specialized to mixotrophic growth.
KeywordsMembrane Fraction Casamino Acid Nitrite Oxidation Mixotrophic Growth Intracytoplasmic Membrane
- py—ni cells
cells grown mixotrophically with nitrite, pyruvate and yeast extract-peptone
- cas—py cells
cells grown he terotrophically with pyruvate and casamino acids
- y—py cells
cells grown heterotrophically with pyruvate and yeast extract-peptone
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