Hans J. Kutzner

Physiology and kinetics of autotrophic denitrification by Thiobacillus denitrificans

SummaryA strain of Thiobacillus denitrificans was isolated after enrichment under anaerobic conditions by the continuous culture technique using thiosulfate as energy source and nitrate as electron acceptor and nitrogen source. The isolate was an active denitrifyer, the optimal conditions being 30°C and pH 7.5–8.0. Denitrification was inhibited by sulfate (the reaction product) above 5 g SO4=/l, whereas high concentrations of the substrates nitrate and thiosulfate were less harmful; nitrite affected denitrification above 0.2 g NO2−/l. During the time course of denitrification in a batch culture growth and substrate consumption slowed down already after only half the substrate was utilized due to product inhibition. The following parameters were determined in continuous culture under nitrate limitation: μmax=0.11 h−1, KS=0.2 mg NO3−/l, maximum denitrification rate=0.78 g NO3−/g cells·h,

Transfer of Faenia rectivirgula Kurup and Agre 1983 to the Genus Saccharopolyspora Lacey and Goodfellow 1975, Elevation of Saccharopolyspora hirsuta subsp. taberi Labeda 1987 to Species Level, and Emended Description of the Genus Saccharopolyspora

Y_{{\text{NO}}_{\text{3}} } = {\text{0}}{\text{.129}}

Thermocrispum gen. nov., a New Genus of the Order Actinomycetales, and Description of Thermocrispum municipale sp. nov. and Thermocrispum agreste sp. nov.

g cells/g NO3−,

Taxonomic Revision of the Genus Saccharomonospora and Description of Saccharomonospora glauca sp. nov.

Y_{{\text{S}}_{\text{2}} {\text{O}}_{\text{3}} } = {\text{0}}{\text{.085}}

Characterization of øGA1, An Inducible Phage Particle from Brevibacterium Flavum

g cells/g S2O3=. Nitrite did not accumulate during steady state denitrification; the denitrification gas was almost pure N2. The concentrations of N2O and NO were below 1 ppm.

Transcription of the tyrosinase gene in Streptomyces michiganensis DSM 40015 is induced by copper and repressed by ammonium

SummaryAn upflow packed bed reactor with lava stones as support for the microbial growth proved to be very useful for the denitrification of industrial waste water by Thiobacillus denitrificans. The application of the plug flow principle allowed higher concentrations of nitrate to be employed than in a stirred tank reactor because inhibitory concentrations of sulfate from thiosulfate oxidation built up only in the upper part of the column — if at all. In experiments with synthetic media nitrate solutions of different strength (NO3−g/l: 1.8; 3.0; 4.3; 6.1) were tested, each at 5 different residence times (5; 3.3; 2.5; 2.0; 1.7 h). The combination of the two parameters which still allowed 95% denitrification was 3 g NO3-/l and 2.5 h residence time; this corresponded to a volumetric nitrate loading of about 25 kg/m3·d. Higher nitrate loadings led to incomplete denitrification coupled with the occurence of nitrite in the outflow. Below the “critical” loading rate nitrite accumulated only in the lower part of the column and was then gradually reduced. Experiments with simulated middle active waste from processing nuclear fuel which contained numerous heavy metals yielded similar results. — Although pure inorganic media were fed into the reactor the microflora developing as a dense layer covering the lava stones consisted not only of T. denitrificans but also of heterotrophic denitrifiers, mainly Pseudomonas aeruginosa.