Application of response surface methodology for poly-§-glutamic acid production by Bacillus subtilis ATCC 6633Author(s): Flavia Oliveira de Araujo, Lucia Helena Mendonca Vargas, Rui Sergio dos Santos Ferreira da Siva, Maria Antonia Pedrine Colabone Celligoi
The objective of this study was to investigate the production of poly-ï§- glutamic acid (ï§-PGA) by Bacillus subtilisATCC 6633, using surface response methodology. Two successive factorial designs were used to determine the sucrose concentration, addition of glutamic acid and time of culture in fermentationmediumfor the production of ï§-PGA. The results of the statistical 23 full factorial design indicated that the linear terms, sucrose concentration, addition of glutamic acid and fermentation time, were significant and positive for the production of the biopolymer. Based on these results, a central composite design was utilized in order to optimize the production of ï§-PGA and define the best concentrations of sucrose and glutamic acid and fermentation time. The best production of ï§-PGA was 20.4 g/l obtained with 132 g/l sucrose, 27.6 g/l glutamic acid and 104 h of fermentation, and the productivity for the maximal production of ï§-PGA was 0.1962 g/l.h-1.