Independent Exponential Feeding of Glycerol and Methanol for Fed-Batch Culture of Recombinant Hansenula polymorpha DL-1

Genome-scale model reconstruction of the methylotrophic yeast Ogataea polymorpha

Background

Ogataea polymorpha is a thermotolerant, methylotrophic yeast with significant industrial applications. While previously mainly used for protein synthesis, it also holds promise for producing platform chemicals. O. polymorpha has the distinct advantage of using methanol as a substrate, which could be potentially derived from carbon capture and utilization streams. Full development of the organism into a production strain and estimation of the metabolic capabilities require additional strain design, guided by metabolic modeling with a genome-scale metabolic model. However, to date, no genome-scale metabolic model is available for O. polymorpha.

Results

To overcome this limitation, we used a published reconstruction of the closely related yeast Komagataella phaffii as a reference and corrected reactions based on KEGG and MGOB annotation. Additionally, we conducted phenotype microarray experiments to test the suitability of 190 substrates as carbon sources. Over three-quarter of the substrate use was correctly reproduced by the model and 27 new substrates were added, that were not present in the K. phaffii reference model.

Conclusion

The developed genome-scale metabolic model of O. polymorpha will support the engineering of synthetic metabolic capabilities and enable the optimization of production processes, thereby supporting a sustainable future methanol economy.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12896-021-00675-w).

A novel strategy and kinetics analysis of half-fractional high cell density fed-batch cultivation of Zygosaccharomyces rouxii

Zygosaccharomyces rouxii is an important microorganism for aroma production in traditional fermented foods. Using Z. rouxii as the original strain, the batch was split after glucose depletion in the culture medium. Half of the volume of the culture medium was released, and fresh culture medium was fed in. The exponential culture kinetics and the formula for the half-fractional fed-batch cultivations were determined to achieve a new strategy for high cell density culturing of Z. rouxii. Based on a full cultivation, three half-fractional fed-batch cultivations were performed after every 10 hr of culture. The specific growth rates of Z. rouxii at the different stages were in the order μ X0>μ X1>μ X2>μ X3 (0.525 to 0.229 hr-1). The glucose substrate consumption rates gradually decreased following the order μ S0>μ S1>μ S2>μ S3 (-1.165 to -0.722, g/g). The equation models for cell growth and glucose substrate consumption showed typical exponential behavior. The total cell yield was 1.78-fold higher than the yield from a full cultivation, and this continuous subculture strategy also indicated a higher efficiency than traditional full cultivation. A new strategy for highly efficient culturing of Z. rouxii was achieved in a pilot scale. A foundation with data support for the production and application of Z. rouxii was developed.