Optimization of fermentation condition for antibiotic production by Alcaligenes faecalis with response surface methodology

The emergence of drug resistant pathogens indicates the need to discovery of new antibiotics. In the search for a new antibiotic producing microorganism, an Alcaligenes faecalis subsp. faecalis strain was isolatedfrom oil polluted soils near Dezful. One factor at a time was used to find important variables in antimicrobial compound production and upon its result pH = 9, temperature 35 ˚C, NH4Cl 0.34%, sodium acetate 2% and K2HPO4 0.02% have greatest effect on production, respectively. Acetate and NH4Cl concentration, shaker revolution and fermentation time were selected for optimization by response surface method with central composite design. The best result achieved by sodium acetate 1.88%, NH4Cl 0.29%, shaker 3 rpm and fermentation time 6.7 day which had 47% higher production than one factor at a time method. Results also indicated strong interaction between some variables.