characteristics of the new genetically modified strains are reported table marker expressed ampr strain host plasmid selection protein presence exp05 03 dh5alpha puc18 kanamycin upase no exp05 04 dh5alpha puc18 kanamycin pnpase no the sequences of the plasmids in the above table are reported in the lists at the end of the description and particularly the sequence of the puc18 plasmid containing the udp gene corresponds to the seq id no 1 and the sequence of the puc18 plasmid containing the deod gene corresponds to the seq id no 2 the recombinant strains called expo5 03 expressing the upase enzyme and expo5 04 expressing the pnpase enzyme were separately fermented batchwise using a fermenter with a useful volume of 15 liters containing 15 l of culture medium with the following composition per liter the fermenter was inoculated with about 150 ml of bacterial suspension previously grown for about 24 h at 37 u00b0 c the fermentation was carried out using the following parameters temperature 37 u00b0 c mechanical stirring at about 250 revolutions minute air flow automatically controlled to keep the po 2 value at 20 of the saturation concentration ph controlled at 7 u00b1 0 2 by addition of 10 ammonia solution or 20 phosphoric acid solution once the fermentation completed in about 24 hours had been terminated the cell paste was collected by centrifugation washed with 100 mm potassium phosphate buffer at ph 7 0 collected again by centrifugation and kept as wet cell paste at a temperature of u2212.