Congrats to Siva Emani, Anton Kan, Timothy Storms, Shanna Bonanno and all the other co-authors on our new paper published in Synthetic Biology! The paper characterizes the relationship between protein secretion and cellular growth. This work was conducted using E. coli Nissle 1917, a probiotic strain, and plasmid variants derived from the presence or absence of the inner/outer membrane secretion tags, and outer membrane secretion machinery to identify major sources of burden. Our results show that growth decline is related to periplasmic accumulation of proteins containing the outer membrane tag, and secretion through the outer membrane. These results motivate additional strategies for optimizing total protein production and secretion for engineered living systems.