English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background  2,3-butanediol (2,3-BD) is a bulk platform chemical with various potential applications such as aviation fuel. 2,3-BD has three optical isomers: (2R, 3R)-, (2S, 3S)- and meso-2,3-BD. Optically pure 2,3-BD is a crucial precursor for the chiral synthesis and it can also be used as anti-freeze agent due to its low freezing point. 2,3-BD has been produced in both native and non-native hosts. Several pathogenic bacteria were reported to produce 2,3-BD in mixture of its optical isomers including  Klebsiella pneumoniae  and  Klebsiella oxytoca . Engineered hosts based on episomal plasmid expression such as  Escherichia coli ,  Saccharomyces cerevisiae  and  Bacillus subtilis  are not ideal for industrial fermentation due to plasmid instability.    Results   Pichia pastoris  is generally regarded as safe and a well-established host for high-level heterologous protein production. To produce pure (2R, 3R)-2,3-BD enantiomer, we developed a  P. pastoris  strain by introducing a synthetic pathway. The  als S and  als D genes from  B. subtilis  were codon-optimized and synthesized. The BDH1 gene from  S. cerevisiae  was cloned. These three pathway genes were integrated into the genome of  P. pastoris  and expressed under the control of GAP promoter. Production of (2R, 3R)-2,3-BD was achieved using glucose as feedstock. The optical purity of (2R, 3R)-2,3-BD was more than 99%. The titer of (2R, 3R)-2,3-BD reached 12 g/L with 40 g/L glucose as carbon source in shake flask fermentation. The fermentation conditions including pH, agitation speeds and aeration rates were optimized in batch cultivations. The highest titer of (2R, 3R)-2,3-BD achieved in fed-batch fermentation using YPD media was 45 g/L. The titer of 2,3-BD was enhanced to 74.5 g/L through statistical medium optimization.    Conclusions  The potential of engineering  P. pastoris  into a microbial cell factory for biofuel production was evaluated in this work using (2R, 3R)-2,3-BD as an example. Engineered  P. pastoris  could be a promising workhorse for the production of optically pure (2R, 3R)-2,3-BD.    Electronic supplementary material  The online version of this article (10.1186/s13068-018-1031-1) contains supplementary material, which is available to authorized users.

Production of (2R, 3R)-2,3-butanediol using engineered Pichia pastoris: strain construction, characterization and fermentation