Bioproduction of succinic acid from xylose by engineered Yarrowia lipolytica without pH control

Abstract

Background Xylose is a most prevalent sugar available in hemicellulose fraction of lignocellulosic biomass (LCB) and of great interest for the green economy. Unfortunately, most of the cell factories cannot inherently metabolize xylose as sole carbon source. Yarrowia lipolytica is a non-conventional yeast to produce industrially important metabolites, and it is able to metabolize a large variety of substrates including both hydrophilic and hydrophobic carbon sources. However, Y. lipolytica lacks effective metabolic pathway for xylose uptake and only scarce information is available on utilization of xylose. For the economically feasible of LCB-based biorefineries, effective utilization of both pentose and hexose sugars is obligatory. Results In the present study, succinic acid (SA) production from xylose by Y. lipolytica was examined. To this end, Y. lipolytica PSA02004 strain was engineered by overexpressing pentose pathway cassette comprising of xylose reductase ( XR ), xylitol dehydrogenase ( XDH ) and xylulose kinase ( XK ) gene. The recombinant strain exhibited a robust growth on xylose as sole carbon source and accumulated SA (3.8 g/L) with a yield of 0.19 g/g in shake flask studies. Substrate inhibition studies revealed a marked negative impact on cell growth and product formation above 60 g/L xylose concentration. The modelling based on inhibition kinetics revealed that Aiba model showed better fit with experimental data, which resulted the correlation coefficient (R 2 ) of 0.82 and inhibition constant (K I ) 88.9 g/L. The batch cultivation of recombinant strain in bioreactor resulted in a maximum biomass concentration of 7.3 g/L and SA titer of 11.2 g/L with the yield of 0.18 g/g. Similar results in term of cell growth and SA production were obtained with xylose-rich hydrolysate derived from sugarcane bagasse. The fed-batch fermentation yielded biomass concentration of 11.8 g/L (OD 600 : 56.1) and SA titer of 22.3 g/L with a gradual decrease in pH below 4.0. Acetic acid was obtained as a main byproduct in all the fermentations. Conclusion The recombinant strain displayed potential bioconversion of xylose to succinic acid. Further this study provided a new insight on conversion of LCB into value-added products. To the best of our knowledge, this is the first study on SA production by Y. lipolytica using xylose as a sole carbon source.

Efficient production of the β-ionone aroma compound from organic waste hydrolysates using an engineered Yarrowia lipolytica strain

“…Although Y. lipolytica has endogenous genes for pentose catabolism (Ryu et al, 2016;Ryu and Trinh, 2018) this yeast cannot use xylose as a sole carbon source (Ledesma- Amaro et al, 2016;Niehus et al, 2018;Ong et al, 2019;Prabhu et al, 2020). Conversely, a synergistic effect of mixed-sugar utilization was reported in Y. lipolytica (Ryu et al, 2016;Ryu and Trinh, 2021), where xylose could be utilized in the presence of a glucose-xylose mixed sugar feedstock.…”

Modular Co-Culture Engineering of Yarrowia Lipolytica for Amorphadiene Biosynthesis

“…Y. lipolytica lacks an effective metabolic pathway for xylose uptake. Efforts have been made to engineer strains that can use xylose as a sole carbon source in the media (45). Due to the ability of engineered strains in a co-culture system to uptake and deal with the mixed feedstock in media and the weakness of Y. lipolytica to uptake xylose as a sole sugar source, we studied co-utilization of 20 g/L xylose with 20 g/L glucose.…”

Bioconversion of Untreated Corn Hull into L-Malic Acid by Trifunctional Xylanolytic Enzyme from Paenibacillus curdlanolyticus B-6 and Acetobacter tropicalis H-1

“…It is noteworthy that L-MA production decreased slightly from day 5 to day 7, which may be due to the limitations of xylose in utilization under the late stationary growth phase, and the possibility to convert small amounts of L-MA to other metabolic intermediates under the TCA cycle. Prabhu et al [38] reported that after the maximum production of succinic acid from xylose by Yarrowia lipolytica, the succinic acid is reduced because it is converted to other by-products. On the other hand, the pH decreased slightly from 6.95 to 6.07 due to the formation of L-MA.…”