The present invention relates to fusion proteins comprising (i) a fusion moiety based on SEQ ID NO:1 and (ii) a protein. Also provided are nucleic acids encoding such fusion proteins and compositions comprising such fusion proteins. The invention also provides a method for increasing the expression level of a protein in a host cell or increasing the level of secretion of a protein from a host cell, said methods employing a fusion moiety in accordance with the invention. The invention further provides a method of producing a protein, said method comprising culturing an Aliivibrio wodanis host cell comprising a heterologous nucleic acid molecule encoding a protein under conditions suitable for the expression of the encoded protein. Certain deposited strains of Aliivibrio wodanis are also provided.