A single celled organism, vector, and method are provided for continuous production of excreted proteins in the absence of substantial host cell replication and without the necessity for the addition of antibiotics to control cell replication. The vector has (1) an inducible promoter capable of activating a gene for a protein to be produced under conditions that substantially inhibit host cell replication, and (2) a hybrid gene containing a signal sequence fused to a gene for the protein to be produced. Large quantities of the transformed single celled organisms containing the vector can be grown in the absence of inducing conditions, thereby reducing the problem of plasmid loss. Further, the protein is produced under conditions that substantially inhibit host cell replication, thereby allowing immobilization of the single celled organism by entrapment or attachment within or onto a solid support surface. The single celled organism can be immobilized after, before or simultaneously with induction. The single celled organism advantageously may be an encapsulated gram-negative bacterium which has no outer membrane or an outer membrane that is permeable to the proteins to be produced so that the protein products are excreted into the media thereby avoiding difficulty in recovering the desired protein products due to the formation of inclusion bodies or the presence of contaminants produced by cell lyses.