The
pET system is commonly used for producing foreign proteins
in Escherichia coli, but its reliance
on the costly and metabolically demanding inducer IPTG limits its
industrial use. This study engineered a low-temperature inducible
system (LTIS) in E. coli Nissle 1917
(EcN) by combining the T7 expression system with the thermal inducible
mechanism CI857-λPRPL to generate the
new LTIS strain, ENL7P. The strain ENL7P-sfGFP-Km underwent overnight
culture at 37 °C for 14–16 h, followed by subculturing
at 30 °C for 24 h. This resulted in a notable 5.53-fold increase
in the sfGFP induction rate when the strain was cultivated under 37–30
°C conditions. Moreover, gene expression was induced using a
two-stage strategy. Initially, the strain was cultured overnight at
39 °C for 14–16 h, followed by a subculture at 30 °C
for 6 h, and finally, another subculture at 30 °C for 24 h. This
cultivation strategy led to an impressive 158.37-fold induction rate
for sfGFP. Similar effects could be achieved through utilization of
the LTIS system for inducing the production of thermophilic trehalose
synthase from Thermus antranikianii (TaTS). The results of this study proved that the LTIS system has
the potential for industrial applications.