Cortez D V, Roberto I C
Department of Biotechnology, College of Chemical Engineering of Lorena, São Paulo, Brazil.
Lett Appl Microbiol. 2006 Apr;42(4):321-5. doi: 10.1111/j.1472-765X.2006.01864.x.
To evaluate the effect of phosphate buffer concentration on growth and xylitol production by Candida guilliermondii FTI 20037.
Fermentations runs were carried out in batch mode employing semisynthetic medium supplemented with phosphate buffer at different concentrations (from 200 to 600 mmol l(-1)). The xylitol yield (Y(P/S)) and volumetric productivity (Q(P)) were improved when the fermentation medium was supplemented with phosphate buffer at concentration of 600 mmol l(-1). Under this condition (Y(P/S)) and (Q(P)) values were 0.75 g g(-1) and 0.66 g l(-1) h(-1), respectively, whereas in the absence of the phosphate buffer these values decreased to 0.52 g g(-1) and 0.44 g l(-1)h(-1) respectively.
The use of phosphate buffer at 600 mmol l(-1) promoted an easier pH control during shake flasks fermentation of C. guilliermondii. In addition the xylitol yield and productivity were significantly improved in response to the supplementation of potassium phosphate in the medium. The increase in these parameters could be related to both osmotic effect and pH control.
This approach provided a method for improving the xylitol production from semisynthetic medium by C. guilliermondii, being possible their use as a simple strategy to achieve efficient fermentation processes employing complex medium such as lignocellulosic hydrolysates.
评估磷酸盐缓冲液浓度对季也蒙毕赤酵母FTI 20037生长及木糖醇产量的影响。
采用分批模式进行发酵，使用添加了不同浓度（200至600 mmol l(-1)）磷酸盐缓冲液的半合成培养基。当发酵培养基中添加浓度为600 mmol l(-1)的磷酸盐缓冲液时，木糖醇产量（Y(P/S)）和体积生产力（Q(P)）得到提高。在此条件下，Y(P/S)和Q(P)值分别为0.75 g g(-1)和0.66 g l(-1) h(-1)，而在不添加磷酸盐缓冲液的情况下，这些值分别降至0.52 g g(-1)和0.44 g l(-1)h(-1)。
在季也蒙毕赤酵母摇瓶发酵过程中，使用600 mmol l(-1)的磷酸盐缓冲液有助于更轻松地控制pH值。此外，培养基中添加磷酸钾可显著提高木糖醇产量和生产力。这些参数的增加可能与渗透效应和pH值控制有关。
该方法为提高季也蒙毕赤酵母从半合成培养基中生产木糖醇提供了一种方法，有可能将其用作一种简单策略，以实现采用复杂培养基（如木质纤维素水解产物）的高效发酵过程。
