Escherichia coli (E. coli) have been widely used genetic model for the production of recombinant proteins. Because of its simplicity in cloning and fast replication, scientists have chosen E. coli to generate higher yields of heterologous proteins. In recent years, the demand for recombinant proteins increased for biomedical applications from basic research to diagnostics. However, the abundance in the expression of soluble recombinant proteins in E. coli is challenging. More often, recombinant proteins misfold and form aggregates in the host. In this chapter, we propose the strategies for enhancing the soluble expression of disulfide bond proteins and non-disulfide bond proteins.