Introduction: Lactate has gained increasing attention as a platform chemical, particularly for the production of the bioplastic poly-lactic acid (PLA).While current microbial lactate production processes primarily rely on the use of sugars as carbon sources, it is possible to envision a future where lactate can be produced from sustainable, non-food substrates.Methanol could be such a potential substrate, as it can be produced by (electro)chemical hydrogenation from CO2.Methods: In this study, the use of the methylotrophic yeast Ogataea polymorpha as a host organism for lactate production from methanol was explored.To enable lactate production in Ogataea polymorpha, four different lactate dehydrogenases were expressed under the control of the methanol-inducible MOX promoter.
The L-lactate dehydrogenase of Lactobacillus helveticus performed well in the yeast, and the lactate production of this engineered strain could jeff rosenstock buffalo additionally be improved by conducting methanol fed-batch experiments in shake flasks.Further, the impact of different nitrogen sources and the resulting pH levels on production was examined more closely.In order to increase methanol assimilation of the lactate-producing strain, an adaptive laboratory evolution experiment was performed.Results and Discussion: The growth rate of the lactate-producing strain on methanol was increased by 55%, while at the same time lactate production was preserved.The highest lactate titer of 3.
8 g/L in this study was obtained by cultivating this evolved strain in a methanol fed-batch experiment in shake flasks with urea as nitrogen source.This study provides a proof of principle that Ogataea polymorpha is a suitable host organism for the production of lactate using methanol as carbon source.In addition, it offers guidance for the engineering of methylotrophic organisms that produce 15-eg2373cl platform chemicals from CO2-derived substrates.With reduced land use, this technology will promote the development of a sustainable industrial biotechnology in the future.