title: Effects of metabolic pathway precursors and polydimethylsiloxane (PDMS) on poly-(gamma)-glutamic acid production by Bacillus subtilis BL53.
abstract: The aims of this study were to evaluate the effects of the addition of metabolic precursors and polydimethylsiloxane (PDMS) as an oxygen carrier to cultures of Bacillus subtilis BL53 during the production of γ-PGA. Kinetics analyses of cultivations of different media showed that B. subtilis BL53 is an exogenous glutamic acid-dependent strain. When the metabolic pathway precursors of γ-PGA synthesis, L-glutamine and a-ketoglutaric acid, were added to the culture medium, production of the biopolymer was increased by 20 % considering the medium without these precursors. The addition of 10 % of the oxygen carrier PDMS to cultures caused a two-fold increase in the volumetric oxygen mass transfer coefficient (kLa), improving γ-PGA production and productivity. Finally, bioreactor cultures of B. subtilis BL53 adopting the combination of optimized medium E, added of glutamine, α-ketoglutaric acid, and PDMS, showed a productivity of 1 g L(-1) h(-1) of g-PGA after only 24 h of cultivation. Results of this study suggest that the use of metabolic pathway precursors glutamine and a-ketolgutaric acid, combined with the addition of PDMS as an oxygen carrier in bioreactors, can improve γ-PGA production and productivity by Bacillus strains .
authors.affiliation: Food Science and Technology Institute, Federal University of Rio Grande do Sul State, Av. Bento Gonçalves 9500, PO Box 15090, Porto Alegre, RS, 91501-970, Brazil.
authors.forename: Alessandra
authors.initials: A
authors.lastname: de Cesaro
authors.forename: Suse Botelho
authors.initials: SB
authors.lastname: da Silva
authors.forename: Marco Antônio Záchia
authors.initials: MA
authors.lastname: Ayub
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D004129:Dimethylpolysiloxanes / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D003470:Culture Media; D004129:Dimethylpolysiloxanes; D007656:Ketoglutaric Acids; C511775:poly(gamma-glutamic acid); D005973:Glutamine; D011099:Polyglutamic Acid; D018698:Glutamic Acid; C013830:baysilon