Reconstruction of amino acid biosynthetic pathways increases the productivity of 2-keto-l-gulonic acid in Ketogulonicigenium vulgare-Bacillus endophyticus consortium via genes screening
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Defect in the amino acid biosynthetic pathways of Ketogulonicigenium vulgare, the producing strain for 2-keto-l-gulonic acid (2-KGA), is the key reason for its poor growth and low productivity. In this study, five different strains were firstly reconstructed by expressing absent genes in threonine, proline and histidine biosynthetic pathways for better 2-KGA productivity. When mono-cultured in the shake flasks, the strain SyBE_Kv02080002 expressing hsk from Gluconobacter oxydans in threonine biosynthetic pathway achieved the highest biomass and the titer increased by 25.13%. When co-cultured with Bacillus endophyticus, the fermentation cycle decreased by 28.57% than that of the original consortium in 5-L fermenter. Furthermore, reconstruction of threonine biosynthetic pathway resulted in up-regulation of genes encoding sorbosone dehydrogenase and idonate-dehydrogenase, which increased the 2-KGA productivity in SyBE_Kv02080002. This study shows that reconstruction of absent biosynthetic pathways in bacteria is an effective way to enhance the productivity of target products.
KeywordsMicrobial consortium Ketogulonicigenium vulgare Bacillus endophyticus 2-Keto-l-gulonic acid Amino acids metabolism
This work was funded by the Ministry of Science and Technology of China (“973” Program: 2014CB745102), the National Natural Science Foundation of China (21390203, 21676190), and the International S&T Cooperation Program of China (2015DFA00960). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Conflict of interest
The authors declare no conflict of interest.
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