AO-09: The effect of ammonium acetate on the productivity of lysine by an auxotrophic mutant of corynebacteruim glutamicum homoserine (-)

Abstract

Subject description: Amongst the main global food crops, many cereal species have a relatively low concentration of the essential amino acid lysine. Many countries, try to develop new sources of proteins and that by the means of the culture of micro-organisms on a large scale to obtain microbial proteins. Objectives: The aim of our work was to study the effect of ammonium acetate used as a source of carbon and nitrogen on the productivity of auxotrophic mutants of corynebacteruim glutamicum homoserine (-), isolated and lyophilized locally by TRAD- KHODJA D. Methods: Four media containing as carbon source (glucose; glucose and ammonium acetate; ammonium acetate; ammonium acetate and sodium acetate) were inoculated by a mutant of Corynebacterium glutamicum auxotroph homoserine (-) and incubated in a rotary shaker at 30 °C/220 r.p.m for 72 hours. During this fermentation, we collected samples of 12ml every 2hours 30min, to monitor the production of biomasse whose concentration is obtained by measuring the optical density at 650 nm using a spectrophotometer; the production of lysine by the strain according to the method of CHINARD (1952) at 479nm; the dosage of glucose by the method "phenol-sulfuric acid" and the concentration of ammonium acetate consumed Results and discussion: We found that in a medium based on ammonium acetate, the fermentation is characterized by a remarkable production of lysine (11.45 g /l) and a low biomass production (20.77g/l). However, the highest production of the biomasse and lysine was noted in the medium containing both glucose and ammonium acetate with 86.06 and 16.3 g/l respectively compared to the medium based on glucose (54.78 and 12.7 g/l respectively). Conclusion: It can be concluded that the production of lysine and biomass by C.glutamicum was proportional to the consumption of glucose and that the production of lysine has no relationship with microbial growth