Adaptive laboratory evolution of Rhodosporidium toruloides to inhibitors derived from lignocellulosic biomass and genetic variations behind evolution

Zhijia Liu,Mohammad Radi,Elsayed T.T Mohamed,Adam M Feist,Giuliano Dragone,Solange I Mussatto

doi:10.1016/j.biortech.2021.125171

Zhijia Liu, Mohammad Radi + Show 4 more

Open Access

https://doi.org/10.1016/j.biortech.2021.125171

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Abstract

Using lignocellulosic biomass hydrolysate for the production of microbial lipids and carotenoids is still a challenge due to the poor tolerance of oleaginous yeasts to the inhibitors generated during biomass pretreatment. In this study, a strategy of adaptive laboratory evolution in hydrolysate-based medium was developed to improve the tolerance of Rhodosporidium toruloides to inhibitors present in biomass hydrolysate. The evolved strains presented better performance to grow in hydrolysate medium, with a significant reduction in their lag phases, and improved ability to accumulate lipids and produce carotenoids when compared to the wild-type starting strain. In the best cases, the lag phase was reduced by 72 h and resulted in lipid accumulation of 27.89 ± 0.80% (dry cell weight) and carotenoid production of 14.09 ± 0.12 mg/g (dry cell weight). Whole genome sequencing analysis indicated that the wild-type strain naturally contained tolerance-related genes, which provided a background that allowed the strain to evolve in biomass-derived inhibitors.

Highlights

In the last years, oleaginous yeasts have attracted increased attention due to their ability to produce lipids and carotenoids from different carbon sources
Biomass hydrolysates usually contain a mixture of different inhibitory compounds and their synergistic effect may strongly affect the microbial performance during fermentation (Mussatto and Roberto, 2004)
The Adaptive laboratory evolution (ALE) strategy used in the present study consisted in using biomass hydrolysate as culture medium for evolution in order to improve the ability of the strain to grow in the presence of different compounds present simultaneously in the medium

Summary

Introduction

Oleaginous yeasts have attracted increased attention due to their ability to produce lipids and carotenoids from different carbon sources. Carotenoids present anti-oxidant and anti-tumor activities, and help reduce the risk of many diseases (Novoveská et al, 2019). These compounds have been widely utilized in food, feed, pharmaceutical and cosmetic industries, and their market is estimated to reach $2.00 billion by 2026 (MarketsandMarkets, 2020). Using oleaginous yeasts to replace edible plants to produce lipids and carotenoids can help reduce the conflict with food production. Seeking for cheap and renewable carbon sources for cultivation of oleaginous yeast is a key strategy to reach this sustainable goal

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