Method for Rapidly Screening Microbial Hosts to Identify Certain Strains with Improved Yield and/or Quality in the Expression of Heterologous Proteins

A method for selecting an optimal expression system for overexpressing at least one heterologous protein, said method comprising:

• assembling an array by placing in separate addressable locations at least 10 nonidentical test expression systems, said at least 10 nonidentical test expression systems each comprising a different combination of
• a) a Pseudomonad or E. coli host cell population, and
• b) at least one expression vector encoding the at least one heterologous protein
• wherein the array includes at least 5 different host cell populations and at least 2 different expression vectors, and further wherein at least 3 of said at least 10 different host cell populations are deficient in their expression of at least one protease;
• measuring the yield of the heterologous protein expressed;
• and
• selecting at least one optimal expression system from among the test expression systems based on the yield of the heterologous protein measured.

An array of expression systems for testing expression of at least one heterologous protein, said array comprising:

• at least 10 nonidentical test expression systems in separate addressable locations, said at least 10 nonidentical test expression systems each comprising a different combination of
• a) a Pseudomonad or E. coli host cell population, and
• b) at least one expression vector encoding at least one heterologous protein,
• wherein the array includes at least 5 different host cell populations and at least 2 different expression vectors, and further wherein at least 3 of said at least 5 different host cell populations are deficient in their expression of at least one protease;
• and wherein at least one of the nonidentical test expression systems overexpresses the heterologous protein.

A method of assembling an array of expression systems for testing expression of at least one heterologous protein, said method comprising:

• placing in separate addressable locations at least 10 nonidentical test expression systems, said at least 10 nonidentical test expression systems each comprising a different combination of
• a) a Pseudomonad or E. coli host cell population, and
• b) at least one expression vector encoding the at least one heterologous protein,
• wherein the array includes at least 4 different host cell populations and at least 2 different expression vectors, and further wherein at least 2 of said at least 4 different host cell populations are deficient in their expression of at least one protease;
• and wherein at least one of the nonidentical test expression systems overexpresses the at least one heterologous protein.