The present invention relates to methods and products for improved production of the lantibiotic mersacidin. There is provided a method of producing a mersacidin variant which comprises introducing into a cell which is a ΔMrsA host cell an expression vector encoding said variant, and recovering said variant from the cell culture. Preferred variants include the novel variants of Table 1, e.g. mersacidin F3W, said mersacidin F3W optionally having a further one or more variations, e.g. mersacidin F3W G8A. Also provided is a Bacillus cell which is a SigH deficient strain of Bacillus sp. HIL Y-85,54728 (NCIMB Accession Number NCIMB 41211); this cell may also be used in the production of mersacidin and its variants. Further aspects of the invention include a DNA cassette which comprises a nucleotide sequence encoding the mersacidin mrsA propeptide, and a method to transform a Bacillus HIL host cell with plasmid, which method includes the step of electroporation.