Abstract The aim of this study was to compare the biofilm production of xanthan gum via immobilization of Xanthomonas campestris cells on different types of support, i.e. smooth small pore size metal support (N1), wavy large pore size metal support (N2) and plastic support (N3), and calcium alginate beads (N4), in a batch condition during 72 h fermentation. The results showed that the recovery of xanthan gum was increased by employing supports. The xanthan recovery was ∼8 and 6 g/L for biofilms N3 and N2, respectively. The chemical structure of xanthan gum produced herein was confirmed by Fourier transform infrared spectrometry and proton nuclear magnetic resonance. Thermal analysis of xanthan using thermo gravimetric analysis gum indicated two fractures which attributed to dehydration and volatile compounds evaporation and degradation of the polysaccharide backbone. Rheological tests exhibited that the G′ values were higher than the G″ values for all frequency, showing high elasticity of the xanthan gum. Furthermore, shear stress vs shear rate data was fitted to the rheological models of power law, Bingham and Casson which indicated the pseudoplastic behavior of xanthan gum solution. Increasing the shear rate from 3.84 to 176.64 (s−1) reduced the apparent viscosity from 2000 to 26 mPa.s.

中文翻译：

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使用固定化油菜黄单胞菌细胞生产黄原胶：载体类型的影响

摘要 本研究的目的是比较通过将油菜黄单胞菌细胞固定在不同类型的载体上生产黄原胶的生物膜，即光滑的小孔径金属载体 (N1)、波浪形的大孔径金属载体 (N2) 和塑料载体。 (N3) 和海藻酸钙珠 (N4)，在 72 小时发酵过程中分批进行。结果表明，使用载体提高了黄原胶的回收率。生物膜 N3 和 N2 的黄原胶回收率分别为~8 和 6 g/L。本文生产的黄原胶的化学结构经傅里叶变换红外光谱和质子核磁共振证实。使用热重分析胶对黄原胶进行的热分析表明，由于脱水和挥发性化合物蒸发以及多糖主链的降解，出现了两处断裂。流变学测试表明，对于所有频率，G' 值均高于 G'' 值，表明黄原胶具有高弹性。此外，剪切应力与剪切速率数据被拟合到幂律流变模型、宾厄姆和卡森，这表明黄原胶溶液的假塑性行为。将剪切速率从 3.84 增加到 176.64 (s-1) 将表观粘度从 2000 降低到 26 mPa.s。剪切应力与剪切速率数据拟合到幂律流变学模型，宾汉姆和卡森，表明黄原胶溶液的假塑性行为。将剪切速率从 3.84 增加到 176.64 (s-1) 将表观粘度从 2000 降低到 26 mPa.s。剪切应力与剪切速率数据拟合到幂律流变学模型，宾汉姆和卡森，表明黄原胶溶液的假塑性行为。将剪切速率从 3.84 增加到 176.64 (s-1) 将表观粘度从 2000 降低到 26 mPa.s。