Pulse Induction System in a set of Artificial Regulons of Bacillus subtilis to Assess Reversible Transcriptional Control

In prokaryotes, transcriptional regulation is required for the cell to quickly adapt to the ever-changing outer environment. In this study, we proposed the artificial operon with capability of reversible transcriptional regulation control based on intrinsically reversible gnt operon in Bacillus subtilis. The results of pulse induction system showed no lacZ activity of each strain in absence of inducer, while the maximum activation of enzyme was observed in 1 h, 2h and 4h after addition of 1, 2.5 and 5 mM gluconate into culture media, respectively. Our data indicated that addition of 1 mM gluconate was enough for normal bacterial growth and transient induction/repression. Also, the longer degradation of inducer and enzyme activity was appeared by more concentration of gluconate which also resulted in growth arrest. However, CAT activity was high even in the absence of inducer due to probably longer half-life of chloramphenicol acetyl transferase than betagalactosidase enzyme, suggesting as more efficient use of lacZ than CAT reporter. We concluded that this reversible artificial operon will be helpful tool in the field of metabolic engineering to achieve adequate amount of metabolite at any desired time.