Transcriptome profiles of central carbon metabolism under autotrophic, heterotrophic, and mixotrophic conditions in Hydrogenophilus thermoluteolus TH-1

Abstract

The facultative chemolithoautotroph, Hydrogenophilus thermoluteolus TH-1 has an ability to grow autotrophically or heterotrophically. In this study, the growth under the mixotrophic condition was demonstrated for the first time with carbon dioxide and butyrate as carbon sources. The transcriptome profiles of the cells grown under the autotrophic, heterotrophic, and mixotrophic conditions were investigated. We re-confirmed the function of Calvin-Benson-Bassham (CBB) cycle as a carbon dioxide fixation pathway under the autotrophic condition. The transcriptome profiles also indicated that the CBB cycle is active under the mixotrophic condition. Quite interestingly, we found the concomitant function of phosphoglycolate phosphatase, glycolate oxidase, and malate synthase under the autotrophic or mixotrophic condition. These reactions were thought to be active for the detoxification of glycolate, which originated from the oxygenase reaction of RubisCO. Furthermore, superoxide dismutase/ peroxidase system was considered to be the primary system to detoxify reactive oxygen species in strain TH-1.