51�Թ�

By contrast, S. oneidensis and G. metallireducens are Gram-negative bacteria, which have two lipid membranes separated by a region called the periplasm that contains cell-wall material.

In these bacteria, tens of haem molecules bound to three types of protein establish a path for electrons to move across the periplasm and the outer lipid membrane8.

In all three papers it is proposed that N-glycan depolymerization occurs primarily in the periplasm.