Liangzhi Li,Lina Gu,Xin Ju,Cuiying Hu,Jiaolong Fu,Hongying Cheng,Pei Kang
This study investigated the production of erythritol by Trichosporonoides oedocephalis in response to the varying osmotic pressure. Osmotic pressure was exerted by adding NaCl or KCl into the fermentation broth. It was demonstrated that appropriate raise in osmotic pressure enhanced erythritol production, wherein 5 g/L KCl addition increased erythritol yield by 44.21% compared to the control. The reason for the significant increase in the erythritol production showed that the 5 g/L KCl addition accelerated the glucose utilization in the late period of fermentation time. It was also revealed that 5 g/L KCl increased the activity of erythrose reductase (ER) in the same fermentation period. In bioreactor, the erythritol yield with initial 5 g/L KCl addition was up to 50.54 g/L, which was 47.69% higher than the control (34.22 g/L). The study provided a novel fermentation regulation, that is, economical addition of KCl made more effective production of erythritol when using T. oedocephalis.
Taotao Zhou,Xin Ju,Lishi Yan,Ruiqi Fang,Xinqi Xu,Liangzhi Li
A large quantity of orange peel waste (OPW) is generated per year, yet effective biorefinery methods are lacking. In this study, Trichosporonoides oedocephalis ATCC 16958 was employed for hydrolyzing OPW to produce soluble sugars. Glycosyl hydrolases from Paenibacillus sp. LLZ1 which can hydrolyze cellulose and hemicellulose were mined and characterized, with the highest β-mannanase activity of 39.1 U/mg at pH 6.0 and 50 ℃. The enzyme was overexpressed in T. oedocephalis and the sugar production was enhanced by 16 %. The accumulated sugar contains 57 % value-added mannooligosaccharides by the hydrolysis of mannans. The process was intensified by a pretreatment combining H 2 O 2 submergence and steam explosion to remove potential inhibitors. The mannooligosaccharides yield of 6.5 g/L was achieved in flask conversion and increased to 9.7 g/L in a 5-L fermenter. This study improved the effectiveness of orange peel waste processing, and provided a hydrolysis-based methodology for the utilization of fruit wastes.
Yue Tang,Xin Ju,Yuqi Peng,Zhicheng Xie,Wei Liu,Jiaolong Fu,Jiajia Chen,Liangzhi Li
D-Arabitol is a naturally occurring pentitol widely used as a low-calorie sweetener and functional ingredient in food formulations. However, microbial production from biomass-derived D-xylose remains constrained by low product titers, limited conversion yields, and the lack of efficient engineered xylose-utilizing strains. In this study, the osmotolerant yeast Trichosporonoides oedocephalis was engineered to produce D-arabitol from D-xylose through the introduction of a heterologous XI (xylose isomerase)-ArDH (arabitol dehydrogenase) pathway. Fermentation conditions relevant to high-sugar food systems were systematically optimized. Compared with the addition of 0.5 g/L KCl (yielding 17.69 g/L D-arabitol), supplementation with 30 g/L KCl significantly increased D-arabitol production, reaching 35.13 g/L in shake flasks and 43.91 g/L in a 5-L bioreactor. Semi-batch fermentation further increased the final titer to 55.21 g/L with a yield of 0.280 g/g. Kinetic analysis indicated predominantly growth-associated D-arabitol formation under these conditions (Luedeking-Piret coefficient, α = 0.61). Comparative transcriptomic analysis revealed that KCl supplementation induced phase-dependent physiological responses, including enrichment of nucleotide metabolism and coordinated transcriptional regulation of central carbon metabolism during exponential growth, as well as increased expression of sugar transport and protein maintenance pathways during the stationary phase. These changes were accompanied by elevated activities of xylose isomerase and arabitol dehydrogenase, suggesting that salt stress is associated with efficient carbon utilization and the biosynthesis of polyols. Importantly, KCl represents a food-compatible and physiologically relevant process regulator, highlighting the potential of salt-mediated metabolic regulation for food-related polyol fermentations. These findings provide an effective strategy for food-related D-arabitol production from xylose and offer insights into salt-associated metabolic regulation in yeast.
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