The Bacillus secretion stress response is an indicator for α-amylase production levels

Aims: Overproduced α-amylases in Bacillus subtilis provoke a specific stress response involving the CssRS two-component system, which controls expression of the HtrA and HtrB proteases. Previously, the B. subtilis TepA protein was implicated in high-level α-amylase secretion. Our present studies were aimed at investigating a possible role of TepA in secretion stress management, and characterizing the intensity of the secretion stress response in relation to α-amylase production. Methods and Results: The expression of a transcriptional htrB–lacZ gene fusion, and the levels of α-amylase production were monitored simultaneously using tepA mutant B. subtilis strains. TepA was shown to be dispensable for secretion stress management. Importantly, however, the levels of htrB-lacZ expression can be correlated with the levels of α-amylase production. Conclusion: Our observations show that the secretion stress response can serve as an indicator for α-amylase production levels. Significance and Impact of Study: Conceivably, this stress response can be employed to monitor the biotechnological production of various secretory proteins by the Bacillus cell factory.