Microcins are small antibacterial proteins (<10 kDa) secreted by gram-negative bacteria.1,2 They recognize specific surface protein receptors of target bacteria and cross the outer membrane, eventually reaching the inner membrane or cytoplasm, where they exert antibacterial action.1,2 Microcins are divided into class I and class II.1,2 Class I microcins are highly post-translationally modified, while class II microcins are either unmodified, except for internal disulfide bonds (class IIa), or...
