Production of alanine by fermentation with Citrobacter intermedium C3

Abstract

Production of Alanine by Fermentation with Citrobacter intermedium C3

Citrobacter intermedium C3 is a strain characterized for to accumulate extracellular aminoacids, growing in a mineral médium with glucose. To stabilize the pH of the médium with calcium carbonate gests the smaller time for to obtain the máximum valué of aminoacids (AA) but the absolute valué remains unchanged. The highest yield in the AA production

against the inicial glucose is for 20 g/1. If the glucose is changed by glycerine, sorbitol or xilose the results are the same. The nitrogen balance-sheet shows a very good acommodation with the AA determinations (Spies & Chambers method). The optimum for the AA acumulation (12 mM) is to 14 g/1 NH.C1 how a inicial

concentration, with an inoculum develo- ped during 48 hours in a médium with only 7 g/1; to these concentration the totalgrowing manifest the only utilisation of 10 % of the available nitrogen, but at lower concentrations decrease the AA ex-tracellular production. The best temperature is 30° C. For the optimum AA ac- cumulation are necessaries a special aireation cónditions, that in a tube scale it is for a oxigen coefficient transport of 0,07 mM02/l/min. May be significant the CO2, parcial prcssure. The biotin and the Tween 60 are not effect in this process. The paper chromatographic determina­ ron shows that the AA are: alanine, glutamate, aspartate and basic aminoacids. The highest alanine proportion is the 70% of the total (2 % of the solids medium and 104 % of the total bacterial growth). The second A in proportion is the glutamate. Tliis should be the first A accumulated, by some lesion in the biochemical regulation, and the others would form by transamination, inclusively the alanine, in spite of its greater abundance.