The present invention provides an array for rapidly identifying a host
cell population capable of producing
heterologous protein with improved yield and / or quality. The array comprises one or more host
cell populations that have been genetically modified to increase the expression of one or more target genes involved in
protein production, decrease the expression of one or more target genes involved in
protein degradation, or both. One or more of the strains in the array may express the
heterologous protein of interest in a periplasm compartment, or may secrete the
heterologous protein extracellularly through an outer
cell wall. The strain arrays are useful for screening for improved expression of any protein of interest, including therapeutic proteins, hormones, a growth factors,
extracellular receptors or ligands,
proteases, kinases,
blood proteins, chemokines, cytokines, antibodies and the like.