Abstract: Caulobacter optimized for use in expression of heterologous peptides as part of a hybrid Caulobacter S-layer protein are provided as well as methods for producing such Caulobacter. Caulobacter of this invention are deficient in a native Caulobacter protease that cleaves hybrid S-layer proteins. Also provided are Caulobacter libraries and methods for sorting such libraries using cell sorting technology such as FACS.

Abstract: DNA constructs are provided which code for at least the extreme C-terminal amino acids of the rsaA protein of Caulobacter crescentus fused with heterologous polypeptides. Baterial cells containing, or which express the DNA constructs and secrete the resulting protein are also provided. Chimeric proteins including the C-terminal amino acids of the rsaA protein are provided, including chimeric proteins comprising antigenic epitopes of the Infectious Hematopoietic Necrosis Virus.

Abstract: DNA constructs are provided which code for at least the extreme C-terminal amino acids of the rsaA protein of Caulobacter crescentus fused with heterologous polypeptides. Baterial cells containing, or which express the DNA constructs and secrete the resulting protein are also provided. Chimeric proteins including the C-terminal amino acids of the rsaA protein are provided, including chimeric proteins comprising antigenic epitopes of the Infectious Hematopoietic Necrosis Virus.

Abstract: DNA constructs are provided which code for a chimeric protein in which the C-terminal region corresponds to the extreme C-terminal amino acids of a Caulobacter S-layer protein, fused with a heterologous polypeptide. Bacterial cells containing the DNA constructs, or which express the DNA constructs and secrete the resulting protein, are provided. Chimeric proteins including the C-terminal amino acids of a Caulobacter S-layer protein are provided, including proteins which include antigenic epitopes of the Infectious Hematopoietic Necrosis Virus.

Abstract: DNA constructs are provided which code for at least the extreme C-terminal amino acids of the rsaA protein of Caulobacter crescentus fused with heterologous polypeptides. Baterial cells containing, or which express the DNA constructs and secrete the resulting protein are also provided. Chimeric proteins including the C-terminal amino acids of the rsaA protein are provided, including chimeric proteins comprising antigenic epitopes of the Infectious Hematopoietic Necrosis Virus.

Abstract: This invention provides a bacterium having an S-layer modified such that the bacterium S-layer protein gene contains one or more in-frame sequences coding for one or more heterologous polypeptides and, the S-layer is a fusion product of the S-layer protein and the heterologous polypeptide. The bacterium is preferably a Caulobacter which may be cultured as a film in a bioreactor or may be used to present an antigenic epitope to the environment of the bacterium. This invention also provides a method of expressing and presenting to the environment of a Caulobacter, a polypeptide that is heterologous to the S-layer of Caulobacter which comprises cloning a coding sequence for the polypeptide in-frame into an S-layer protein gene of Caulobacter whereby the polypeptide is expressed and presented on the surface of the Caulobacter as a fusion product of the S-layer protein and the polypeptide in the S-layer of the Caulobacter.