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A novel approach targeting self-inducible surfactin synthesis under oxygen-limited conditions is presented. Because both the nitrate (NarGHI) and nitrite (NasDE) reductase are highly expressed during anaerobic growth of  B. subtilis , the native promoter P  srfA   of the surfactin operon in strain  B. subtilis  JABs24 was replaced by promoters P  narG   and P  nasD   to induce surfactin synthesis anaerobically. Shake flask cultivations with varying oxygen availabilities indicated no significant differences in native P  srfA   expression. As hypothesized, activity of P  narG   and P  nasD   increased with lower oxygen levels and surfactin was not produced by P  srfA  ::P  narG   as well as P  srfA  ::P  nasD   mutant strains under conditions with highest oxygen availability. P  narG   showed expressions similar to P  srfA   at lowest oxygen availability, while maximum value of P  nasD   was more than 5.5-fold higher. Although the promoter exchange P  srfA  ::P  narG   resulted in a decreased surfactin titer at lowest oxygen availability, the strain carrying P  srfA  ::P  nasD   reached a 1.4-fold increased surfactin concentration with 696 mg/L and revealed an exceptional high overall  Y  P/X  of 1.007 g/g. This value also surpassed the  Y  P/X  of the reference strain JABs24 at highest and moderate oxygen availability. Bioreactor cultivations illustrated that significant cell lysis occurred when the process of “anaerobization” was performed too fast. However, processes with a constantly low agitation and aeration rate showed promising potential for process improvement, especially by employing the strain carrying P  srfA  ::P  nasD   promoter exchange. Additionally, replacement of other native promoters by nitrite reductase promoter P  nasD   represents a promising tool for anaerobic-inducible bioprocesses in  Bacillus .   Supplementary Information  The online version contains supplementary material available at 10.1186/s13568-021-01218-4.

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Evaluation of an oxygen‐dependent self‐inducible surfactin synthesis in B. subtilis by substitution of native promoter PsrfA by anaerobically active PnarG and PnasD