These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
Gas-phase bioproduction, in which immobilized biocatalysts are employed and chemical reactions are performed in a gas phase, has attracted researchers’ attention as a green process. However, there is difficulty in the employment of whole cell catalysts for gas-phase bioproduction due to the lack of a suitable cell immobilization method. Acinetobacter sp. Tol 5 is a unique bacterium, which is remarkably sticky and can be easily immobilized onto various material surfaces through the adhesive bacterionanofiber protein AtaA. In this study, we demonstrate the gas-phase bioproduction of (E)-geranic acid (GA), a high-value-added monoterpenoid, from geraniol using immobilized Tol 5 transformant cells, into which a gene involved in a (E)-GA synthetic pathway was introduced. Time course analysis of the liquid-phase bioproduction of (E)-GA revealed the inherent metabolism of Tol 5 involved in the degradation of (E)-GA. By disrupting the fadD4-ortholog gene, which encodes a key enzyme of the (E)-GA degradation, we successfully generated a (E)-GA-accumulating strain, Tol 5 ΔfadD4 (pGeoA). The immobilized cells of this mutant strain on a polyurethane support enabled the production of (E)-GA with a passive supply of gaseous geraniol in a batch gas-phase reaction. A major fraction of the (E)-GA, which was produced, was adsorbed onto the polyurethane support but easily extracted into ethanol, a safe solvent without environmental impact. This is the first example of gas-phase bioproduction of a complex and high-value-added compound. Tol 5 is a highly promising platform for gas-phase bioproduction.