title: Processing parameters matching effects upon Rhizobium tropici biopolymers' rheological properties.
abstract: The combined effects of the processing parameters upon rheological properties of biopolymers produced by Rhizobium tropici were studied as a function of the Ca(+2) ions' concentration variation, yeast extract concentration added to the medium, aeration, and agitation, maintaining the mannitol concentration in 10 g/L. The experiments were carried out using a fermenter with 20-L capacity as a reactor. All processing parameters were monitored online. The temperature [(30 +/- 1) degrees C] and pH values (7.0) were kept constant throughout the experimental time. As a statistical tool, a complete 2(3) factorial design with central point and response surface was used to investigate the interactions between relevant variables of the fermentation process: calcium carbonate concentration, yeast extract concentration, aeration, and agitation. The processing parameter setup for reaching the maximum response for rheological propriety production was obtained when applying mannitol concentration of 10.0 g/L, calcium carbonate concentration 1.0 g/L, yeast extract concentration 1.0 g/L, aeration 1.30 vvm, and agitation 800 rpm. The viscosimetric investigation of polysaccharide solutions exposed their shear-thinning behavior and polyelectrolytic feature.
authors.affiliation: Chemical and Textile Industry Technological Center, Textile Industrial Engineering, Rio de Janeiro, Brazil. fpduta@hotmail.com
authors.forename: Flávia Duta
authors.initials: FD
authors.lastname: Pimenta
authors.forename: Léa Maria de Almeida
authors.initials: LM
authors.lastname: Lopes
authors.forename: Francisca Pessôa
authors.initials: FP
authors.lastname: de França
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D019149:Bioreactors; D003470:Culture Media; D007218:Industrial Microbiology; D016555:Matched-Pair Analysis; D012212:Rheology; D042162:Rhizobium tropici / Q000737:chemistry*
chemical_list: D001704:Biopolymers; D003470:Culture Media