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Efficient xylose utilization leads to highest lipid productivity in Candida tropicalis SY005 among six yeast strains grown in mixed sugar medium.
Applied Microbiology and Biotechnology ( IF 3.9 ) Pub Date : 2020-02-19 , DOI: 10.1007/s00253-020-10443-z
Atrayee Chattopadhyay 1 , Mrinal K Maiti 1
Affiliation  

Six local isolates of yeasts were screened for cell mass and lipid production in mixed glucose and xylose medium. Candida tropicalis SY005 and Trichosporon (Apiotrichum) loubieri SY006 showed significant lipid accumulation of 24.6% and 32% (dry cell weight), respectively when grown in medium containing equal mass of both the sugars. SY005 produced relatively higher cell mass of 9.66 gL-1 due to higher rate of sugar consumption, which raised the lipid productivity of the organism to 0.792 gL-1day-1 as compared to 0.446 gL-1day-1 in SY006. When grown with each sugar separately, the xylose consumption rate of SY005 was found to be 0.55 gL-1 h-1 after 4 days as compared to 0.52 gL-1 h-1 for SY006. Transcript expression of the high affinity xylose transporter (Cthaxt), xylose reductase (Ctxyl1), and xylitol dehydrogenase (Ctxyl2) of SY005 was monitored to unravel such high rate of sugar consumption. Expression of all the three genes was observed to vary in mixed sugars with Cthaxt exhibiting the highest expression in presence of only xylose. Expression levels of both Ctxyl1 and Ctxyl2, involved in xylose catabolism, were maximum during 24-48 h of growth, indicating that xylose utilization started in the presence of glucose, which was depleted in the medium after 96 h. Together, the present study documents that C. tropicalis SY005 consumes xylose concomitant to glucose during early period of growth, and it is a promising yeast strain for viable production of storage lipid or other high-value oleochemicals utilizing lignocellulose hydrolysate.

中文翻译:

在混合糖培养基中生长的六种酵母菌株中,有效利用木糖可以使热带假丝酵母SY005的脂质生产率最高。

在混合的葡萄糖和木糖培养基中筛选了六个酵母的局部分离株的细胞质量和脂质产生。当在含有相等质量的两种糖的培养基中生长时,热带假丝酵母SY005和Trichosporon(Apiotrichum)loubieri SY006分别显示出显着的脂质蓄积,分别为24.6%和32%(干细胞重量)。由于较高的糖消耗速率,SY005产生了相对较高的9.66 gL-1细胞质量,与SY006中的0.446 gL-1day-1相比,该生物的脂质生产率提高到0.792 gL-1day-1。当分别与每种糖一起生长时,发现SY005的木糖消耗率在4天后为0.55 gL-1 h-1,而SY006的木糖消耗率为0.52 gL-1 h-1。高亲和力木糖转运蛋白(Cthaxt),木糖还原酶(Ctxyl1)的转录表达 并监测了SY005的木糖醇脱氢酶(Ctxyl2),以揭示如此高的糖消耗率。观察到所有三个基因的表达在混合糖中变化,而Cthaxt在仅木糖的情况下表现出最高的表达。木糖分解代谢中涉及的Ctxyl1和Ctxyl2的表达水平在生长的24-48小时内达到最高,表明木糖的利用在葡萄糖存在下开始,葡萄糖在96小时后被耗尽。总之,本研究表明,热带假丝酵母SY005在生长的早期消耗木糖,同时它是葡萄糖,它是一种有希望的酵母菌株,可利用木质纤维素水解物切实生产储存脂质或其他高价值的油脂化学产品。观察到所有三种基因的表达在混合糖中均发生变化,其中Cthaxt仅在木糖存在下表现出最高的表达。木糖分解代谢中涉及的Ctxyl1和Ctxyl2的表达水平在生长的24-48小时内达到最高,表明木糖的利用在葡萄糖存在下开始,葡萄糖在96小时后被耗尽。总之,本研究表明,热带假丝酵母SY005在生长的早期消耗木糖,同时它是葡萄糖,它是一种有希望的酵母菌株,可利用木质纤维素水解产物可靠地生产储存脂质或其他高价值的油脂化学品。观察到所有三种基因的表达在混合糖中均发生变化,其中Cthaxt仅在木糖存在下表现出最高的表达。木糖分解代谢中涉及的Ctxyl1和Ctxyl2的表达水平在生长的24-48小时内达到最高,表明木糖的利用在葡萄糖存在下开始,葡萄糖在96小时后被耗尽。总之,本研究表明,热带假丝酵母SY005在生长的早期消耗木糖,同时它是葡萄糖,它是一种有前景的酵母菌株,可利用木质纤维素水解物切实生产储存脂质或其他高价值的油脂化学产品。在生长的24-48小时内,木糖利用率达到最大值,这表明木糖的利用是在葡萄糖存在下开始的,葡萄糖在96小时后在培养基中被消耗掉。总之,本研究表明,热带假丝酵母SY005在生长的早期消耗木糖,同时它是葡萄糖,它是一种有前景的酵母菌株,可利用木质纤维素水解物切实生产储存脂质或其他高价值的油脂化学产品。在生长的24-48小时内,木糖利用率达到最大值,表明木糖利用是在葡萄糖存在下开始的,葡萄糖在96小时后被耗尽。总之,本研究表明,热带假丝酵母SY005在生长的早期消耗木糖,同时它是葡萄糖,它是一种有前景的酵母菌株,可利用木质纤维素水解物切实生产储存脂质或其他高价值的油脂化学产品。
更新日期:2020-03-19
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