Amperometric determination of ammonium ions with a microbial sensor.

A sensor for NH+4 ions has been developed, which consists of immobilized micro-organisms (Bacillus subtilis, Pseudomonas aeruginosa, Trichosporon cutaneum) in combination with an electrochemical transducer. This sensor is based on the measurement of acceleration of respiration after addition of NH+4 in the presence of glucose. The physiological background of this signal and its connection with NH+4 ion uptake and/or metabolism is discussed.

A novel L-glutamate oxidase from Streptomyces endus. Purification and properties.

A new flavoenzyme using molecular oxygen to oxidize L-glutamic acid has been purified to homogeneity, as judged by polyacrylamide gel electrophoresis, from the culture medium of Streptomyces endus. Hydrogen peroxide, 2-oxoglutaric acid and ammonia are formed as products. Among 25 amino acids tested including D-glutamic acid, L-glutamine and L-aspartic acid, only L-glutamic acid is converted.

Formation of some extracellular enzymes during the exponential growth of Bacillus subtilis.

The formation of the exoenzymes, neutral and alkaline proteinase as well as alpha-amylase of Bacillus subtilis, is characterized by the same time course. The exoenzyme formation starts in the exponential phase of growth by an excess of C and N sources. We assume that carbon metabolism of pyruvate is responsible for the exoenzyme formation during this growth phase.

[Nitrogen regulation in microorganisms].

The central role of NH4+-assimilation in the microbial metabolization of several inorganic nitrogen sources and the regulation of its key enzymes--glutamate dehydrogenases (GDH--EC 1.4.1.

Formation of extracellular neutral proteinase and the stringent response in Bacillus subtilis.

The kinetics of extracellular neutral proteinase synthesis by an isogenic stringent (IS58) and a relaxed (IS56) strain of B. subtilis were compared. The specific enzyme formation rate by the stringent strain was higher than that of the relaxed one.