Figure 6From: The Bacillus BioBrick Box: generation and evaluation of essential genetic building blocks for standardized work with Bacillus subtilisInference of promoter activity from luminescence measurements. (A) Quantitative mathematical model used to infer the underlying promoter activity from luminescence time-series. Here, the promoter activity is reflected in a time-dependent transcription rate, α(t). luxABCDE mRNA is degraded at rate log(2)/τm , translated at rate β into Lux proteins, which are in turn degraded at rate log(2)/τp. For simplicity, the model assumes a single Lux protein species, which is rate-limiting for luciferase activity and considered to be directly proportional to luminescence output. (B) As a test case for our method, the luciferase activity of pBS3Clux-P liaI (TMB1858) induced with 30 μg/ml bacitracin (symbols) was fitted by our quantitative mathematical model (solid lines). Since the luxABCDE mRNA half-life is unknown in B. subtilis, we fitted the data using a physiological spectrum of half-lives (τm = 3, 5 and 10 min) and found that the model can reproduce the highly dynamic luciferase activity (arrow) only for mRNA half-lives of 5 min and shorter. (C) Underlying apparent promoter activity in arbitrary units (au) for the fits in (B). For all details see main text.Back to article page