Biologically synthesized magnetic particles by magnetotactic bacteria (BacMPs) have promising potential in the area of functional protein display technology for various biotechnological and biomedical applications. Functional proteins fused with an anchor protein, Mms13, have been demonstrated to be an effective and stable method for the display of functional proteins on BacMPs. However, the expression of some human proteins is relatively low. Useful host strains of Escherichia coli have been developed for the enhanced expression of recombinant proteins using a genetic engineering approach. To improve human protein expression level on BacMPs in Magnetospirillum magneticum AMB-1, a mutant strain with a deleted native mms13 gene (Δmms13 strain) was established and evaluated for effective functional protein display technology. As a result, the Δmms13 strain synthesized BacMPs with significantly improved expression of two human proteins, thyroid-stimulating hormone receptor (TSHRaa1-165) and the class II major histocompatibility complex (MHC II) molecules. The Δmms13 strain could therefore be an effective strain for the display of other important human proteins on BacMPs and may be useful for further applications.