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Everaldo Silvino dos Santos,Carlos Eduardo de Araújo Padilha,Nathália Kelly de Araújo,Domingos Fabiano de Santana Souza,Jackson Araújo de Oliveira,Gorete Ribeiro de Macedo 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.9
A phenomenological model was used to describe sequentially the three steps (flowthrough, washing and elution) of expanded bed adsorption chromatography for recovery of chitosanases from Bacillus cereus. Additionally, a hybrid strategy for model parameter estimation was carried out using particle swarm optimization and Gauss-Newton algorithms. The model was validated with independent experimental data and the statistical criteria (χ 2 and mean squared error tests) showed that the hybrid strategy was more promising than just the heuristic method. With the calibrated model, surface response methodology was applied to obtain the optimal operational conditions, and experiments were performed to confirm these results. Overall, a value of 41.08% for yield was obtained using 700mM NaCl during elution. In summary, all approach employed in this work was relevant for maximizing the yield of the chromatographic process.
Sergio Carvalho de Santana,Everaldo Silvino dos Santos,Raimundo Cosme da Silva Filho,Jorge dos Santos Cavalcanti,Jackson Araujo de Oliveira,Gorete Ribeiro de Macedo,Francine Ferreira Padilha 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.4
A mathematical model was developed to predict breakthrough curves during purification of the two chitosanasesfrom Metarhizium anisopliae by expanded bed adsorption, taking into account the axial dispersion of liquid andusing Streamline DEAE and SP XL adsorbents, anion and cation exchange resins, respectively. All the experimentswere performed without clarification (with cells) aiming at the reduction of unit operations in future projects of separationprocesses, thereby reducing capital and operating costs. Chitosanases are enzymes that hydrolyze the carbohydratechitosan, resulting in oligosaccharides that have many remarkable biological activities, such as anti-cancer, anti-HIVand antioxidant activities. The two adsorbents had similar performance in relation to hydrodynamics and mass transfer. The results of the parametric sensitivity analysis agree with the literature, and the model was validated with an averagehigh degree of fit (94.68%) between simulated and experimental data obtained in this work.
OsAMT1.3 expression alters rice ammonium uptake kinetics and root morphology
Leandro Martins Ferreira,Vinicius Miranda de Souza,Orlando Carlos Huertas Tavares,Everaldo Zonta,Claudete Santa-Catarina,Sonia Regina de Souza,Manlio Silvestre Fernandes,Leandro Azevedo Santos 한국식물생명공학회 2015 Plant biotechnology reports Vol.9 No.4
High-affinity ammonium transporters (AMT1) are responsible for ammonium (NH4 ?) acquisition and/or perception in the micromolar range, and their expressions can be differentially regulated by nitrogen (N) availability. The present study characterised the functions of the rice (Oryza sativa) OsAMT1.3 transporter to understand its contribution to NH4+ acquisition and plant adaptation to environments with low N availability. Transgenic rice plants were obtained to study the activity of the OsAMT1.3 promoter (POsAMT1.3:GFP:GUS) and the overexpression of the OsAMT1.3 gene (UBIL:OsAMT1.3:3xHA) in plants. The OsAMT1.3 promoter activity was induced strongly in the absence of N and occurred primarily in the zones of lateral root emission and root tips. Anatomical sections of the segment of root tips and the middle third showed a differential pattern of OsAMT1.3 activity. Analysis of the OsAMT1.1–1.3 transporter expression profiles indicated that overexpression of OsAMT1.3 positively affected OsAMT1.2 expression. When subjected to a low N supply, plants overexpressing OsAMT1.3 showed lower KM and Cmin values. Additionally, these lines showed longer roots with a higher area, volume, and number of tips. The data suggested that OsAMT1.3 is involved in the ability of rice plants to adapt to low NH4+ supplies.