OK and NB conceived the study. MB designed and performed the experimental part using L. lactis as nisin production host. TB and JN designed and performed the experimental part using E. coli as nisin production host. DP and RW designed and produced the amber codon scanned library of nisA. MB and TB drafted and wrote the manuscript. OK and NB equally contributed to the revision of the manuscript to obtain the final version. All contributors read and approved the final version of this manuscript.