Fig. 4.

Ferric reductase activity in E. coli and B. japonicum cells. The production of ferrous ferrozine produced by whole cells was measured and is presented as nanomoles of ferrous iron produced per hour. Ferric reductase activity is expressed as nanomoles of Fe²⁺ produced/hour/10⁹ cells, and the values are presented as the averages plus standard deviations (error bars) of three replicate samples. (A) B. japonicum wild-type (WT) or frcB mutant strains were grown in low-iron media (Fe −) or supplemented with 12 μM FeCl₃ (Fe +). (B) E. coli DH5α harboring empty vector (pSK) or vector plus bll3557 (frcB) (pSKfrcB), grown in LB medium.