This study demonstrates that inoculum choice significantly impacts early performance, microbial adaptation, and stability of TBR systems in CO conversion. The reactor inoculated with AS stabilized at higher LRCO, achieving reliable CO conversion more quickly. In contrast, reactors inoculated with AD and CM adapted more slowly, with the CM reactor requiring a lower CO loading rate. The slower adaptation in the CM reactor was likely due to differences in microbial community composition and the need for sufficient enrichment of CO-utilizing functional groups.