The refolding level of thermally inactivated bacterial luciferases by trigger factor (TF) of the mesophilic bacterium Escherichia coli (TF_Ec) and the psychrophilic bacterium Psychrobacter frigidicola (TF_Pf) was measured. Refolding of heat inactivated luciferases reached a maximum of 25-30% in E. coli ΔdnaKdnaJ cells containing plasmids with a tig gene (encoding TF) and luxAB genes (encoding heterodimeric (αβ) luciferase from Photobacterium leiognathi). However, while the activity of TF_Ec was characterized by a significant reduction in refolding with an increase in TF concentration, the chaperone activity of the psychrophilic TF remained at a plateau at higher concentrations. TF_Pf also did not affect the growth kinetics of the host bacterial cells at high TF concentrations, unlike TF_Ec, which exerted a lethal effect on bacterial cells with increased concentration. Moreover, TF_Ec and TF_Pf effectively assisted in refolding dimeric forms of luciferase but were unable to refold an enzyme variant in monomeric form. Finally, luciferase refolding by TF_Pf was found to be more efficient in E. coli strains lacking the ClpB chaperone than in clpB⁺ strains.