Abstract: A method of producing a protein or polypeptide, in which an expression vector that encodes a fusion protein comprising the protein or polypeptide peptide located carboxy-terminally to YebF, or a biologically active variant or portion thereof, is expressed in a suitable bacterial cell, to make the fusion protein. The method may further comprise the step of purifying the secreted fusion protein from the growth medium. The fusion protein may further comprise a peptide tag, or a protein cleavage site to separate the protein or polypeptide from the YebF portion, or the tag. Expression of a fusion protein into the culture medium provides a starting material for purification, in which the secreted fusion protein is relatively pure.