Metabolic Engineering Group, Departamento de Microbiología Y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
J Ind Microbiol Biotechnol. 2020 Dec;47(12):1173-1179. doi: 10.1007/s10295-020-02320-5. Epub 2020 Oct 9.
The co-utilization of mixed (pentose/hexose) sugars constitutes a challenge for microbial fermentations. The fungus Ashbya gossypii, which is currently exploited for the industrial production of riboflavin, has been presented as an efficient biocatalyst for the production of biolipids using xylose-rich substrates. However, the utilization of xylose in A. gossypii is hindered by hexose sugars. Three A. gossypii homologs (AFL204C, AFL205C and AFL207C) of the yeast HXT genes that code for hexose transporters have been identified and characterized by gene-targeting approaches. Significant differences in the expression profile of the HXT homologs were found in response to different concentrations of sugars. More importantly, an amino acid replacement (N355V) in AFL205Cp, introduced by CRISPR/Cas9-mediated genomic edition, notably enhanced the utilization of xylose in the presence of glucose. Hence, the introduction of the afl205c-N355V allele in engineered strains of A. gossypii will further benefit the utilization of mixed sugars in this fungus.
混合（戊糖/己糖）糖的共同利用对微生物发酵构成了挑战。木霉（Ashbya gossypii）真菌目前被用于工业生产核黄素，它被认为是利用富含木糖的底物生产生物脂的有效生物催化剂。然而，木糖在木霉中的利用受到己糖的阻碍。通过基因靶向方法，已经鉴定并表征了编码己糖转运蛋白的酵母 HXT 基因的三个木霉同源物（AFL204C、AFL205C 和 AFL207C）。发现 HXT 同源物的表达谱在不同糖浓度下有显著差异。更重要的是，通过 CRISPR/Cas9 介导的基因组编辑引入 AFL205Cp 中的氨基酸替换（N355V），显著增强了在葡萄糖存在下利用木糖的能力。因此，在木霉工程菌株中引入 afl205c-N355V 等位基因将进一步有利于该真菌混合糖的利用。
