The relative expression of prtA, psaB, psaC, psaA, and pcpA genes was normalized with the housekeeping gene gyrA.

aGene numbers refer to D39 locus tags.bD39 annotation/TIGR4 annotation. [34,62]The log2 fold increase is relative to the expression in the D39 wild-type grown in CDMchelex with 0.3 mM Ni2+ to that with 0 mM Ni2+. Standard deviation of three independent replications is given in parentheses.