Demirci Ali, Cotton Julie C, Pometto Anthony L, Harkins Kristi R, Hinz Paul N
Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, PA 16802, USA.
Biotechnol Bioeng. 2003 Sep 30;83(7):749-59. doi: 10.1002/bit.10722.
Lactic acid fermentations were performed with plastic-composite-support (PCS) disks in solvent-saturated media with Lactobacillus casei subsp. rhamnosus (ATCC 11443). The PCS disks contained 50% (w/w) polypropylene, 35% (w/w) ground soybean hulls, 5% (w/w) yeast extract, 5% (w/w) soybean flour, and 5% (w/w) bovine albumin. Bioassays were performed by growing L. casei in solvent-saturated media after soaking the PCS disks. Eighteen different solvent and carrier combinations were evaluated. Overall, L. casei biofilm fermentation demonstrated the same lactic acid production in solvent-saturated medium as suspended cells in medium without solvents (control). To evaluate PCS solvent-detoxifying properties, two bioassays were developed. When solvent-saturated medium in consecutive equal volumes (10 mL then 10 mL) was exposed to PCS, both media demonstrated lactic acid fermentation equal to the control. However, when solvent-saturated medium with two consecutive unequal volumes (10 mL then 90 mL) was exposed to PCS, some degree of toxicity was observed. Furthermore, iso-octane, tributylphosphate (TBP), and Span 80 were optimized for recovery as 91%, 5%, and 4% (v/v), respectively, with a 1:1 ratio of 1.2 M Na(2)CO(3) stripping solution. Also, recovery by emulsion liquid extraction in the hollow-fiber contactor was minimal due to low recovery at pH 5.0 and incompatibility of the solvent and hollow-fiber material. These results suggest that PCS biofilm reactors can benefit lactic acid fermentation by eliminating the toxic effect from solvent leakage into the fermentation medium from liquid-liquid extractive integrated fermentations.
在含有干酪乳杆菌鼠李糖亚种（ATCC 11443）的溶剂饱和培养基中，使用塑料复合载体（PCS）圆盘进行乳酸发酵。PCS圆盘包含50%（w/w）聚丙烯、35%（w/w）磨碎的大豆壳、5%（w/w）酵母提取物、5%（w/w）大豆粉和5%（w/w）牛白蛋白。在浸泡PCS圆盘后，通过在溶剂饱和培养基中培养干酪乳杆菌进行生物测定。评估了18种不同的溶剂和载体组合。总体而言，干酪乳杆菌生物膜发酵在溶剂饱和培养基中产生的乳酸量与在无溶剂培养基（对照）中的悬浮细胞相同。为了评估PCS的溶剂解毒特性，开发了两种生物测定方法。当连续等体积（10 mL然后10 mL）的溶剂饱和培养基与PCS接触时，两种培养基的乳酸发酵均与对照相当。然而，当连续不等体积（10 mL然后90 mL）的溶剂饱和培养基与PCS接触时，观察到了一定程度的毒性。此外，异辛烷、磷酸三丁酯（TBP）和司盘80分别以91%、5%和4%（v/v）的回收率进行了优化回收，使用的1.2 M Na₂CO₃反萃溶液的比例为1:1。而且，由于在pH 5.0时回收率低以及溶剂与中空纤维材料不相容，中空纤维接触器中的乳液液液萃取回收率极低。这些结果表明，PCS生物膜反应器可以通过消除液液萃取集成发酵中溶剂泄漏到发酵培养基中产生的毒性作用，使乳酸发酵受益。
