title: Production and optimization of poly-γ-glutamic acid by Bacillus subtilis BL53 isolated from the Amazonian environment.
abstract: The aims of this research were to screen and characterize a new microbial source of γ-PGA, to optimize aspects of culture conditions and medium composition using central composite design and response surface methodologies. The influence of bioreactor stirring rates on the production of γ-PGA was also investigated and the oxygen volumetric mass transfer coefficients (k La) were established. The most productive strain was identified by 16S rDNA analysis as Bacillus subtilis, and its γ-PGA production in rotatory shaker was threefold increased under optimized conditions (37 °C, pH 6.9, and 1.22 mM Zn(2+)), compared to conventional medium. In bioreactor, the γ-PGA production was further increased, reaching 17 g l(-1), 70 % higher than shaker cultures. γ-PGA production showed high dependency on oxygen transfer. At k La of 210 h(-1), the cultivation time could be reduced to 48 h, about 50 % of the time required for operations at k La 55 h(-1).
authors.affiliation: Food Engineering, Polytechnic School, Vale do Rio dos Sinos University, Av. Unisinos, 950, São Leopoldo, RS, 93022-000, Brazil.
authors.forename: Suse Botelho da
authors.initials: SB
authors.lastname: Silva
authors.forename: Vlademir Vicente
authors.initials: VV
authors.lastname: Cantarelli
authors.forename: Marco Antonio Záchia
authors.initials: MA
authors.lastname: Ayub
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019149:Bioreactors; D001938:Brazil; D003470:Culture Media; D004275:DNA, Ribosomal / Q000235:genetics; D007700:Kinetics; D011099:Polyglutamic Acid / Q000096:biosynthesis*; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D003470:Culture Media; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D011099:Polyglutamic Acid