Transcriptomic characterisation of novelly isolated Brucella sp. strain by utilising iron as electron donor for carbon dioxide biofixation

The biofixation of carbon dioxide (CO 2 ) by chemoautotrophic microorganisms has garnered substantial research attention. Zero-valent iron has been considered an outstanding electron donor, however, studies on iron-driven CO 2 biofixation remain limited. Brucella sp. WYQ-2 was firstly time isolated and demonstrated efficient CO 2 fixation at rate of 4.7 g/(m 3 ·d) using iron as sole electron donor. The optimal culture conditions were 80 g/m 3 CO 2 , 1 g iron, and a neutral pH, the tolerated CO 2 concentration was up to 130 g/m 3 (66 % v/v). Furthermore, more than 95 % of CO 2 was converted to biomass and organic compounds (methane, acetate, and cyclobutanol), and the acetate yield was 36.4 mg/L. Transcriptomic analyses further revealed that three CO 2 bioconversion pathways of Wood-Ljungdahl pathway, C4-dicarboxylic acid cycle, and reductive tricarboxylic acid cycle were involved. Overall, this study enriched the species of CO 2 reduction and provided a promising candidate for CO 2 biofixation in future full-scale applications.