In this study, minicell-forming mutants have been constructed to increase the production of value-added chemicals. Minicell-forming mutants have improved tolerance to toxic chemicals and showed higher intracellular NADH/NAD+ rate than wild types. When toxic chemicals such as isobutanol, isobutyraldehyde, and isobutyl acetate were produced in this mutant, the titers increased by 67%, 175%, and 214%, respectively. In addition, morphological changes and membrane dispersion mechanisms in minicell-forming mutants improved lycopene production by 259%. This increase in production capacity was more pronounced when biomass hydrolysate was used as the substrate.
In addition, minicells possess functional metabolism despite their inability to grow and divide. Minicells exhibit not only superior stability when compared with bacterial cells but also exceptional tolerance-characteristics that are essential for a de novo bioreactor platform. To understand the biological properties of minicells and to produce toxic chemicals using them, minicells were designed. The minicells were constructed to accumulate target proteins and showed advantages over bacterial cells in C6-C10 alcohol and ester production. When chemicals restricted from production in bacterial cells such as hexanol, octanol, phenethyl acetate, and butyl butyrate were produced in the engineered minicells, the titers increased by 1875%, 300%, 542%, and 254%, respectively, compared to the bacterial production.
The production capacity of these minicells also was used to perform the production microbial autoinducer production that is limited in expanding bacterial population. Because bacterial population growth was nonexistent, the minicells produced autoinducers in constant amounts, which allowed precise control of the bacterial population having autoinducer-responsive gene circuits.
These results indicate that minicell-forming mutants are an excellent platform for biochemical production. Additionally, this study demonstrates the potential of minicells as bioreactors suitable for products with known limitations in microbial production, thus providing new possibilities for bioreactor engineering.