The invention provides improvements of lantibiotics useful for reducing the numbers of microbes or the reproduction of microbes in or on subjects or objects. One embodiment of the invention provides variants of antibiotics wherein the amino acid at position (1) is changed to Ile or Gly, the amino acid at position (4) is changed to an Ala, the amino acid at position (4) is removed, the amino acid at position (5) is changed to an Ala, or wherein, as in the case of MU1140, the amino acid at position (13) is Arg, the Arg at position (13) is substituted with Asp, or combinations of two or more these changes or a pharmaceutically acceptable salt thereof.