Tavares JM, Duarte LC, Amaral-Collaço MT, Gírio FM
Unidade de Microbiologia Industrial e Bioprocessos, Departamento de Biotecnologia, IBQTA, INETI, Azinhaga dos Lameiros 1649-038, Lisboa, Portugal
Enzyme Microb Technol. 2000 Jun 1;26(9-10):743-747. doi: 10.1016/s0141-0229(00)00166-6.
The effect of hexoses (glucose and galactose) addition to the feed xylose mineral medium of Debaryomyces hansenii chemostat cultures grown at a constant dilution rate of 0.055 h(-1) was studied. Xylitol was the major product detected amongst all tested conditions. The maximal values for xylitol yield and volumetric productivity (0.56 gg(-1) xylose and 0.21 gl(-1)h(-1), respectively) were obtained for a glucose/xylose feeding ratio of 10%, showing that the addition of small amounts of glucose, but not galactose, enhanced the xylitol production. A xylitol yield increase of 30%, compared with the sole xylose-containing feed medium, was observed. It was found that the oxygen requirement for D. hansenii growth is lower under glucose compared with xylose. Ethanol and glycerol were only produced for glucose/xylose feeding ratio above 30%. The byproducts accumulation was correlated with glucose metabolism, because a direct relationship between the increase of ethanol (and glycerol) concentration and the increase of glucose in the feed medium was found.
研究了在以0.055 h⁻¹的恒定稀释率生长的汉逊德巴利酵母恒化器培养物的饲料木糖矿物培养基中添加己糖（葡萄糖和半乳糖）的效果。木糖醇是在所有测试条件下检测到的主要产物。对于葡萄糖/木糖进料比为10%的情况，获得了木糖醇产量和体积生产率的最大值（分别为0.56 gg⁻¹木糖和0.21 gl⁻¹h⁻¹），表明添加少量葡萄糖而非半乳糖可提高木糖醇产量。与仅含木糖的进料培养基相比，木糖醇产量提高了30%。结果发现，与木糖相比，汉逊德巴利酵母在葡萄糖条件下生长所需的氧气较少。仅当葡萄糖/木糖进料比高于30%时才会产生乙醇和甘油。副产物的积累与葡萄糖代谢相关，因为发现进料培养基中乙醇（和甘油）浓度的增加与葡萄糖的增加之间存在直接关系。
