The direct conversion of xylan to lactic acid by Lactobacillus brevis transformed with a xylanase gene
The direct conversion of xylan to lactic acid by Lactobacillus brevis transformed with a xylanase gene
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DOI：
10.1039/c1gc15169j
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发表时间：
2011-01-01
期刊：
影响因子：
9.8
通讯作者：
Chen, Yo-Chia
中科院分区：
文献类型：
--
作者：
Hu, Chun-Yi;Chi, Da-Jun;Chen, Yo-Chia
木聚糖酶基因（xynR8），从一个池的未培养的瘤胃微生物的DNA，通过质粒导入短乳杆菌。重组木聚糖酶在转化子中表达，分子量约为32 KDa，与野生型短乳杆菌ATCC 367相比，对燕麦木聚糖的酶活为0.412 U ml~（-1）。转化子都具有相似的利用和代谢低聚木糖的能力。当将选择的木聚糖酶接种到含有木聚糖作为主要碳源的改良MRS培养基中时，细胞密度在第4天达到2.20 × 10（9）CFU ml（-1），而不含含有重组木聚糖酶的质粒的野生型菌株在相同条件下根本不生长。发酵后，含有重组木聚糖酶的菌株的培养上清液中存在1.70 g l（-1）的乳酸和0.44 g l（-1）的乙醇。这些结果表明，含有木聚糖酶基因的短乳杆菌能够一步直接糖化发酵木聚糖生产乳酸。该菌株将能够开发一种可行且经济的方法来直接从木聚糖生产乳酸。
A xylanase gene (xynR8), obtained from the DNA of a pool of uncultured rumen microbes, was introduced via a plasmid into Lactobacillus brevis. The recombinant xylanase, with an estimated molecular weight of 32 KDa, was expressed in the transformants and showed obvious xylanase activity (0.412 U ml(-1)) against oat-spelt xylan in broth when compared to the wild-type Lactobacillus brevis ATCC367. The transformants all shared a similar ability to utilize and metabolize xylooligosaccharides. When a selected transformant was inoculated into modified MRS medium containing xylan as the main carbon source, the cell density reached 2.20 x 10(9) CFU ml(-1) on day 4, while the wild-type strain without the plasmid containing the recombinant xylanase did not grow at all under the same conditions. After fermentation, 1.70 g l(-1) of lactic acid and 0.44 g l(-1) of ethanol were present in the culture supernatant of the strain containing the recombinant xylanase. These results indicate that Lactobacillus brevis containing the xylanase gene is capable of directly saccharifying and fermenting xylan to produce lactic acid in one step. This strain will enable the development of a feasible and economical approach to the production of lactic acid directly from xylan.