Presentation Information
[1ASBA-12-KL]Engineering the acid-tolerant yeast Issatchenkia orientalis for low-pH bioconversion of lignocellulosic hydrolysates to value-added products
○Yong-Su Jin1,2 (1. University of Illinois, Urbana-Champaign (USA), 2. Illinois Advanced Research Center at Singapore (Singapore))
Keywords:
Lignocellulose,Xylose,Ethanol,3-Hydroxypropionic acid,Lactic acid
Lignocellulosic biomass is an abundant and sustainable carbon source for next-generation biorefineries. However, its microbial conversion to value-added products remains challenging due to incomplete xylose utilization, the presence of toxic inhibitors, and limited nutrient availability. In addition, microbial conversion of lignocellulosic hydrolysates into organic acids typically requires pH control at neutral levels, which increases downstream processing costs. These limitations highlight the need for robust microbial platforms capable of efficient conversion under low-pH, inhibitor-rich, and nutrient-limited conditions.
Here, we engineered the acid and inhibitor-tolerant yeast Issatchenkia orientalis as a versatile host for low-pH bioconversion of lignocellulosic hydrolysates. We established a Cas9-based genome-editing system using the cloNAT resistance marker, enabling rapid and auxotrophy-independent genome engineering across diverse I. orientalis strains. Introduction of a heterologous xylose utilization pathway consisting of XYL1, XYL2, and XYL3 from Scheffersomyces stipitis enabled efficient xylose utilization and revealed a strong dependence of fermentation performance on host strain background.
Engineered strains were further tailored for the production of organic acids directly from lignocellulosic hydrolysates. A 3-hydroxypropionic acid (3-HP)-producing strain produced 56 g/L of 3-HP from sorghum hydrolysate without nutrient supplementation. A lactic acid-producing strain produced 67 g/L of lactic acid from glucose and xylose mixtures that mimic sorghum hydrolysates. In addition, a partial pH control strategy, in which pH was maintained only during early fermentation, was effective in improving productivity.
Together, these results establish engineered xylose-utilizing I. orientalis as a robust platform for converting lignocellulosic hydrolysates into fuels and organic acids via nutrient-independent and low-pH bioconversion processes, highlighting its potential for sustainable, cost-effective industrial biomanufacturing.
Here, we engineered the acid and inhibitor-tolerant yeast Issatchenkia orientalis as a versatile host for low-pH bioconversion of lignocellulosic hydrolysates. We established a Cas9-based genome-editing system using the cloNAT resistance marker, enabling rapid and auxotrophy-independent genome engineering across diverse I. orientalis strains. Introduction of a heterologous xylose utilization pathway consisting of XYL1, XYL2, and XYL3 from Scheffersomyces stipitis enabled efficient xylose utilization and revealed a strong dependence of fermentation performance on host strain background.
Engineered strains were further tailored for the production of organic acids directly from lignocellulosic hydrolysates. A 3-hydroxypropionic acid (3-HP)-producing strain produced 56 g/L of 3-HP from sorghum hydrolysate without nutrient supplementation. A lactic acid-producing strain produced 67 g/L of lactic acid from glucose and xylose mixtures that mimic sorghum hydrolysates. In addition, a partial pH control strategy, in which pH was maintained only during early fermentation, was effective in improving productivity.
Together, these results establish engineered xylose-utilizing I. orientalis as a robust platform for converting lignocellulosic hydrolysates into fuels and organic acids via nutrient-independent and low-pH bioconversion processes, highlighting its potential for sustainable, cost-effective industrial biomanufacturing.
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