Development of Fluorescence-Based Reporter Systems for Acetogenic Bacterium, Eubacterium callanderi KIST612

Abstract

Eubacterium callanderi KIST612, an acetogen and anaerobic bacterium, is a promising biocatalyst for using C1 gases (e.g., CO and CO2) to produce valuable chemicals. Despite its whole genome and genetic toolboxes secured, establishing the reporter system is still required for better suitability and sensitivity due to limitations in some available reporter genes and strain characteristics. The objective of this study is to establish fluorescent reporter systems to effectively operate in anaerobic and CO-rich conditions. As an initial step, we investigated the intrinsic fluorescence (autofluorescence) properties of the strain to avoid high background signals. After analyzing the autofluorescence (420-440/480-530 nm) of wild-type E. callanderi KIST612 using excitation- emission matrix (EEM) data, fluorescence-activating and absorption-shifting tag (FAST) were tested. The obtained data showed that FAST could be expressed in E. callanderi KIST612 under anaerobic and CO-rich condition. To test the capability under various CO conditions, FAST was applied to CO-sensing biosensor in E. coli DH5α. This study seeks to create a comprehensive fluorescent reporter system that is applicable to E. callanderi KIST612 and could be extended to other acetogenic strains.