Effectiveness of the Bacillus subtilis genome-reduced strain as an ethanol production host

• Published in: Bioscience, biotechnology, and biochemistry Vol. 86; no. 4; pp. 543 - 551
• Main Authors: Grinanda, Dita, Hirasawa, Takashi
• Format: Journal Article
• Language: English
• Published: England 21.03.2022
• Subjects: Bacillus subtilis - genetics; Bacillus subtilis - metabolism; Ethanol - metabolism; Fermentation; Lactic Acid - metabolism; Zymomonas - genetics; genome-reduced strain; Bacillus subtilis; ethanol
• ISSN: 1347-6947; 1347-6947
• DOI: 10.1093/bbb/zbac017

We investigated the performance of a genome-reduced strain of Bacillus subtilis MGB874, whose 0.87 Mbp of genomic DNA was cumulatively deleted, as an ethanol production host. A recombinant strain A267_EtOH was constructed by introducing the pdc and adhB genes from Zymomonas mobilis, both of which were expressed from an isopropyl-β-d-1-thiogalactopyranoside-inducible spac promoter, into the A267 strain, a tryptophan prototrophic derivative of the MGB874 with disruption of metabolic pathways for producing lactic acid, acetic acid, and acetoin. Focusing on the stationary phase in fed-batch fermentation, 1.6 g L-1 ethanol was produced by the A267_EtOH strain after 144 h. Moreover, its ethanol production further increased by approximately 3.7-fold (5.9 g L-1) at 80 h through replacing the spac promoter for expressing pdc and adhB genes with the lytR promoter and the yield was about 112%. These results indicate that the MGB874 is an effective host for ethanol production during the stationary phase.