The effect of ammoniumon the fermentative production of gentamicin in Micromonospora purpurea has been studied using a chemically defined medium. Ammoniumchloride concentrations ranging from 20 to 1 50 mMresulted in a proportional stimulation of growth and antibiotic formation. The use of other ammonium salts exerted a similar effect. Amongthe products of ammonium assimilation, glutamate and glutamine were able to exert the stimulatory effect. In addition, both amino acids reproduced the stimulation in resting cell systems of this microorganism and this result was not modified by the presence of chloramphenicol, eliminating a possible inductive action as the cause of this effect. The use of a glutamine synthetase inhibitor prevented antibiotic formation. This inhibition was reverted only by glutamine, suggesting that this amino acid was responsible of ammonium stimulation. Glutamine stimulation seems to be due to its ability to produce 2-deoxystreptamine and glucosamine, intermediates of the gentamicin biosynthetic pathway.

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La videovigilancia en la Ciudad de México constituye una de las infraestructuras urbanas importantes que se han construido en los inicios del siglo XXI, en paralelo con una tendencia histórica en la urbanización global. Nace de un proyecto de reorganización del Centro Histórico bajo condiciones de acumulación privada de un actor principal tanto inmobiliario como tecnológico, y se ha extendido al conjunto de la ciudad, dándole un sello actual de modelo de seguridad basada en vigilancia electrónica.