iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, 1049-001, Portugal.
Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, 1049-001, Portugal.
Sci Rep. 2024 Oct 8;14(1):23366. doi: 10.1038/s41598-024-74919-y.
The oleaginous yeast species Rhodotorula toruloides is a promising candidate for applications in circular bioeconomy due to its ability to efficiently utilize diverse carbon sources being tolerant to cellular stress in bioprocessing. Previous studies including genome-wide analyses of the multi-stress tolerant strain IST536 MM15, derived through adaptive laboratory evolution from a promising IST536 strain for lipid production from sugar beet hydrolysates, suggested the occurrence of significant modifications in the cell wall. In this study, the cell wall integrity and carbohydrate composition of those strains was characterized to gain insights into the physicochemical changes associated to the remarkable multi-stress tolerance phenotype of the evolved strain. Compared to the original strain, the evolved strain exhibited a higher proportion of glucomannans, fucogalactomannans, and chitin relative to (1→4)-linked glucans, and an increased presence of glycoproteins with short glucosamine derived oligosaccharides, which have been found to be associated to ethanol stress tolerance and physical strength of the cell wall. Furthermore, the evolved strain cells were found to be significantly smaller than the original strain and more resistant to thermal and mechanical disruption, consistent with higher proportion of beta-linked polymers instead of glycogen, conferring a more rigid and robust cell wall. These findings provide further insights into the cell wall composition of this basidiomycetous red yeast species and into the alterations occurring in a multi-stress tolerant evolved strain. This new information can guide yeast genome engineering towards more robust strains of biotechnological relevance.
油脂酵母属物种罗伦隐球酵母由于其能够有效利用多种碳源，并且在生物加工过程中耐受细胞应激，因此是循环生物经济中极具应用前景的候选菌株。先前的研究包括对多应激耐受菌株 IST536 MM15 的全基因组分析，该菌株是通过适应性实验室进化从生产糖甜菜水解物的有前途的 IST536 菌株中衍生而来，表明细胞壁发生了重大变化。在这项研究中，对这些菌株的细胞壁完整性和碳水化合物组成进行了表征，以深入了解与进化菌株显著的多应激耐受表型相关的物理化学变化。与原始菌株相比，进化菌株的（1→4）-连接葡聚糖的比例更高，而甘露糖醛酸聚糖、几丁质和葡聚糖的比例更高，并且短葡糖胺衍生低聚糖的糖蛋白含量增加，这些低聚糖与乙醇应激耐受和细胞壁物理强度有关。此外，与原始菌株相比，进化菌株的细胞明显更小，并且对热和机械破坏的抵抗力更强，这与更多的β-连接聚合物而不是糖原有关，赋予细胞壁更刚性和更强的结构。这些发现进一步了解了这种担子菌红色酵母属物种的细胞壁组成以及多应激耐受进化菌株中发生的变化。这些新信息可以指导酵母基因组工程，以获得更具生物技术相关性的更健壮菌株。
