Abstract
BackgroundA microorganism engineered for non-native tasks may suffer stresses it never met before. Therefore, we examined whether a Kluyveromyces marxianus strain engineered with a carotenoid biosynthesis pathway can serve as an anti-stress chassis for building cell factories.ResultsCarotenoids, a family of antioxidants, are valuable natural products with high commercial potential. We showed that the free radical removal ability of carotenoids can confer the engineered host with a higher tolerance to ethanol, so that it can produce more bio-ethanol than the wild type. Moreover, we found that this engineered strain has improved tolerance to other toxic effects including furfurals, heavy metals such as arsenate (biomass contaminant) and isobutanol (end product). Furthermore, the enhanced ethanol tolerance of the host can be applied to bioconversion of a natural medicine that needs to use ethanol as the delivery solvent of hydrophobic precursors. The result suggested that the engineered yeast showed enhanced tolerance to ethanol-dissolved hydrophobic 10-deacetylbaccatin III, which is considered a sustainable precursor for paclitaxel (taxol) bioconversion.ConclusionsThe stress tolerances of the engineered yeast strain showed tolerance to several toxins, so it may serve as a chassis for cell factories to produce target products, and the co-production of carotenoids may make the biorefinary more cost-effective.
Highlights
A microorganism engineered for non-native tasks may suffer stresses it never met before
As the colony color was correlated with the carotenoids amount produced, one of the light red colonies was selected and denoted as Cz5 strain and the reddest colony was selected and denoted as the Cz30 strain
Among the three growth temperatures (25 °C, 30 °C and 37 °C), the strongest color was found at 25 °C (Additional file 1: Fig. S1)
Summary
A microorganism engineered for non-native tasks may suffer stresses it never met before. We examined whether a Kluyveromyces marxianus strain engineered with a carotenoid biosynthesis pathway can serve as an anti-stress chassis for building cell factories. Due to the increasing demand of alternative fuel and biopharmaceuticals, people are looking for reliable and sustainable ways to produce various bio-products. Synthetic biology, which can be used to design and integrate new biological functions into a cell, provides a powerful way to engineer a microbe for a sustainable bio-industry. Its broad applications can incorporate desirable bio-processes into a designer host to convert. Liu et al Microb Cell Fact (2019) 18:155 tolerance against n-butanol by scavenging intracellular or extracellular ROS [6, 7]. The yeast Kluyveromyces marxianus was used as the host because it has several desirable characteristics for industrial applications. K. marxianus is GRAS (generally regarded as safe) and QPS (qualified presumption of safe) and has been widely employed in various biotechnological applications and food industry [9]
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