Efficient production of L-lactic acid from xylose by Pichia stipitis
Efficient production of L-lactic acid from xylose by Pichia stipitis
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DOI：
10.1128/aem.01311-06
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发表时间：
2007-01-01
影响因子：
4.4
通讯作者：
Penttila, Merja
中科院分区：
文献类型：
--
作者：
Ilmen, Maria;Koivuranta, Kari;Penttila, Merja
微生物将可再生原料转化为有用的产品是工业生物技术的重要目标。树干毕赤酵母，一种天然发酵木糖的酵母，被基因工程改造用于L-（+）-乳酸盐的生产。我们构建了在树干毕赤酵母发酵ADHI启动子控制下表达来自瑞士乳杆菌的L-乳酸脱氢酶（LDH）的树干毕赤酵母菌株。木糖、葡萄糖或两种糖的混合物用作乳酸盐生产的碳源。构建的树干毕赤酵母菌株产生更高水平的乳酸盐，并且对木糖的产率高于对葡萄糖的产率。在含木糖的培养基中乳酸作为主要产物积累，从100 g/L木糖产生58 g/L乳酸。在葡萄糖培养基上也发生相对有效的乳酸盐生产，从94 g/L葡萄糖产生41 g/L乳酸盐。在两种糖的存在下，木糖和葡萄糖被同时消耗，并主要转化为乳酸。乳酸的产生是以乙醇为代价的，乙醇的产生在含木糖的培养基上降低到野生型水平的15 - 30%，在含葡萄糖的培养基上降低到野生型水平的70 - 80%。因此，LDH有效地与丙酮酸的乙醇途径竞争，即使从丙酮酸到乙醇的途径是完整的。我们的研究结果表明，第一次，乳酸生产木糖的酵母菌是可行的和有效的。这对于进一步开发基于酵母的生物工艺以从木质纤维素原料生产乳酸盐是令人鼓舞的。
Microbial conversion of renewable raw materials to useful products is an important objective in industrial biotechnology. Pichia stipitis, a yeast that naturally ferments xylose, was genetically engineered for L-(+)-lactate production. We constructed a P. stipitis strain that expressed the L- lactate dehydrogenase (LDH) from Lactobacillus helveticus under the control of the P. stipitis fermentative ADHI promoter. Xylose, glucose, or a mixture of the two sugars was used as the carbon source for lactate production. The constructed P. stipitis strain produced a higher level of lactate and a higher yield on xylose than on glucose. Lactate accumulated as the main product in xylose-containing medium, with 58 g/liter lactate produced from 100 g/liter xylose. Relatively efficient lactate production also occurred on glucose medium, with 41 g/liter lactate produced from 94 g/liter glucose. In the presence of both sugars, xylose and glucose were consumed simultaneously and converted predominantly to lactate. Lactate was produced at the expense of ethanol, whose production decreased to similar to 15 to 30% of the wild-type level on xylose-containing medium and to 70 to 80% of the wild-type level on glucose-containing medium. Thus, LDH competed efficiently with the ethanol pathway for pyruvate, even though the pathway from pyruvate to ethanol was intact. Our results show, for the first time, that lactate production from xylose by a yeast species is feasible and efficient. This is encouraging for further development of yeast-based bioprocesses to produce lactate from lignocellulosic raw material.