The expression of acetate assimilation system encoded by acs-yjcH-actP operon was highly induced during APEC early colonization in lung tissues in vivo. A For duck model, qRT-PCR data acquired from three individual experiments were used to determine the transcription of acs, yjcH, actP, satP, ackA, and pta genes during wild-type FY26 colonization in duck organs in vivo at 24 hpi. Transcriptional differences of these genes were determined relative to that of the routine condition in vitro. B For chick model, transcriptional differences of acs, yjcH, actP, satP, ackA, and pta genes during FY26 colonization in chick tissues in vivo at 24 hpi were determined relative to that of the routine condition in vitro. Significant differences of qRT-PCR results were identified using one-way ANOVA statistical analysis (*P < 0.01).