Transcriptomic Insights into the Adaptive Colonization of Escherichia coli O157:H7 during Production and Storage of Alfalfa Sprout

STEC further adapted to sprout environment by inducing high-affinity uptake systems for potassium (kdpA/B/C/F), phosphorus (pstSCAB), and sulfur (tauABCD), alongside enterobactin-mediated iron acquisition. To survive sprout microenvironment, STEC elevated the transcription of acid resistance (gadA/C, cadA/B), oxidative stress defense (sodA, katE/G), and envelope protection (degP, pspA–D, baeS) genes. Although initial colonization at D5 involved the induction of flagellar components, the transition to a sessile biofilm-associated lifestyle at D8 was marked by the repression of motility genes and the strong induction of curli fimbriae (csg) and colanic acid (wca) loci.

Functional enrichment at D5 and D8, compared to D0, indicated coordinated stress regulation and translation. The major transcriptional trends observed in RNA seq were confirmed using RT-qPCR. Collectively, these findings highlight a multi tiered molecular adaptation strategy, enabling STEC adaptation and persistence in sprout environment, thus, providing insights that could be translated into STEC risk mitigation during sprout production