探討信號肽對木聚醣酶於枯草芽孢桿菌RIK1285之外泌活性影響

利用植物性蛋白替代魚粉作為飼料來源會影響魚隻腸道型態，導致營養吸收力下降，此負面影響源自於非澱粉多醣類，而植物細胞壁結構主要成分的木聚醣即為其中一種。木聚糖可被木聚醣酶所分解，木聚醣酶是一種糖苷酶，它能催化水解木聚醣中的1,4-β- D-木糖苷鍵，以解決木聚醣帶來的負面影響。枯草芽孢桿菌E20可從發酵大豆產品中分離取得，應用於水生生物上能夠提升成長以及免疫能力。本實驗選殖枯草芽孢桿菌E20的木聚醣酶基因 (BsXynE20)，並利用枯草芽孢桿菌RIK1285來表達含有173種信號肽之重組木聚醣酶，以達到利用枯草芽孢桿菌高效率分泌木聚醣酶的目的。本實驗根據DNS法檢測木聚醣酶的外泌效率，結果發現信號肽ydjM、ybbc、mpr、aprE以及ypfZ的外泌能力顯著高於BsXynE20本身信號肽 (XynE)，換句話說，實驗結果證明了信號肽能夠影響蛋白質的外泌能力。而本研究也提供了改善木聚醣酶生產的的一種可行方案，以此提供充足的來源以利產業應用所需。

關鍵字

枯草芽孢桿菌；木聚醣酶；信號肽；外泌表現

並列摘要

Replacing the fish meal by vegetable protein may influence the gut morphology and lead to a reduced nutrient digestibility. This negative impact is caused from non-starch polysaccharides. Xylan is a major structural in plant cells wall which is also a kind of non-starch polysaccharides. Xylanases are glycosidases which catalyze the endohydrolysis of 1,4-β-D-xylosidic linkages in xylan, can solve the impact of xylan. Bacillus subtilis isolated from fermented soy product was able to increase the growth and immunity in aquatic species. In this study, we subcloned the xylanase gene of B. subtilis E20 (BsXynE20) into pBE-S expression vector fusioned with 173 of different signal peptides (SPs) to produce recombinant xylanase in Bacillus subtilis RIK1285. The recombinant protein with the efficient secretion of xylanase activity could be detected in B. subtilis RIK1285 cells. The library was assayed the efficiency of xylanase secretion by DNS method. The ydjM, ybbc, mpr, aprE and ypfZ SPs enhanced the secretion of the xylanase efficiently, which were significant higher than the SP of BsXynE20 (XynE). In other words, this result confirmed that signal peptide can enhance the secretory expression of recombinant proteins. This study showed a method to improve the xylanase producing, and hope to meet demand in industry.

並列關鍵字

Bacillus subtilis ； Xylanase ； Signal peptide ； Secretion

參考文獻

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