Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325, USA.
Appl Microbiol Biotechnol. 2018 Jan;102(2):641-653. doi: 10.1007/s00253-017-8626-5. Epub 2017 Nov 17.
Arabitol is a low-calorie sugar alcohol with anti-cariogenic properties. Enzymatic hydrolysate of soybean flour is a new renewable biorefinery feedstock containing hexose, pentose, and organic nitrogen sources. Arabitol production by Debaryomyces hansenii using soybean flour hydrolysate was investigated. Effects of medium composition, operating conditions, and culture stage (growing or stationary phase) were studied. Production was also compared at different culture volumes to understand the effect of dissolved oxygen concentration (DO). Main factors examined for medium composition effects were the carbon to nitrogen concentration ratio (C/N), inorganic (ammonium) to organic nitrogen ratio (I/O-N), and sugar composition. Arabitol yield increased with increasing C/N ratio and a high I/O-N (0.8-1.0), suggesting higher yield at stationary phase of low pH (3.5-4.5). Catabolite repression was observed, with the following order of consumption: glucose > fructose > galactose > xylose > arabinose. Arabitol production also favored hexoses and, among hexoses, glucose. DO condition was of critical importance to arabitol production and cell metabolism. The yeast consumed pentoses (xylose and arabinose) only at more favorable DO conditions. Finally, arabitol was produced in fermentors using mixed hydrolysates of soy flour and hulls. The process gave an arabitol yield of 54%, volumetric productivity of 0.90 g/L-h, and specific productivity of 0.031 g/g-h.
阿拉伯糖醇是一种低热量糖醇，具有抗龋特性。大豆粉的酶解产物是一种新型可再生生物炼制原料，含有己糖、戊糖和有机氮源。本研究考察了利用大豆粉水解物生产阿拉伯糖醇的过程。研究了培养基组成、操作条件和培养阶段（生长或静止期）的影响。还比较了不同培养体积下的生产情况，以了解溶解氧浓度（DO）的影响。考察培养基组成影响的主要因素是碳氮比（C/N）、无机（铵）与有机氮比（I/O-N）和糖组成。阿拉伯糖醇的产率随着 C/N 比的增加和高 I/O-N（0.8-1.0）而增加，表明在低 pH（3.5-4.5）的静止期产率更高。观察到分解代谢物阻遏，消耗顺序为：葡萄糖＞果糖＞半乳糖＞木糖＞阿拉伯糖。阿拉伯糖醇的生产也有利于己糖，在己糖中，葡萄糖优先。DO 条件对阿拉伯糖醇的生产和细胞代谢至关重要。酵母只有在更有利的 DO 条件下才消耗戊糖（木糖和阿拉伯糖）。最后，在发酵罐中使用大豆粉和豆壳的混合水解物生产阿拉伯糖醇。该工艺的阿拉伯糖醇产率为 54%，体积产率为 0.90 g/L-h，比产率为 0.031 g/g-h。
