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[Metabolism of ammonium compounds by Azotobacter chroococcum (author's transl)].

A study on the metabolism of ammonium sulphate, amino acids, peptides, and nutrient broth by Azotobacter chroococcum is presented in this paper. Some of the amino acids studied lowered the pH of the medium while others alkalinized it. After prolonged incubation desamination could be observed. Peptides were hydrolyzed in some cases, although glycyl-glycyl-glycin was not degraded. A certain amount of growth could be observed with peptone as a sole source of carbon. Both nitrogen fixation and growth were stimulated by nutrient broth, but the medium was alkalinized when a higher concentration of nutrient broth was used, due to the production of ammonia.

Amines

Direct spectorphotometric assay of quaternary ammonium compounds using bromthymol blue.

Benzalkonium chloride, benzethonium chloride, and chlorhexidine gluconate were assayed quantitatively by a direct spectrophotometric method with bromthymol blue buffered at pH 7.5. The method shows good results at concentrations of 0--300 microgram/ml and in the presence of epinephrine bitartrate, phenylephrine hydrochloride, pilocarpine hydrochloride, and polyvinyl alcohol.

Benzalkonium Compounds

Secretion of monoquaternary ammonium compounds by guinea pig small intestine in vivo.

In anesthetized guinea pigs N-(3H)methylscopolamine (NMScop), N1-(14C)methylnicotinamide (NMN), and (14C)tetraethylammonium (TEA), administered intravenously, were secreted against a concentration gradient into the lumen of the small intestine. The concentration ratio of unmetabolized ammonium base in the intestinal lumen to that in the plasma was 4.3 and 6.5 for NMScop and NMN, respectively, 75 min after the intravenous injection of 1 nmole/g body weight of the individual compounds. The corresponding value for TEA after 180 min was 2.0. The establishment of the concentration gradient between intestinal lumen and plasma was diminished with increasing doses. An excess of NMN inhibited the uphill transport of NMScop. Since the electrical potential difference across the intestinal epithelium and a 'fluid circuit' mechanism cannot solely account for the observed accumulation of the monoquaternary ammonium compounds in the intestinal lumen, the evidence presented supports previous in vitro findings that the small intestine is capable of actively secreting organic cations.

Animals