Tuning cell surface charge in E. coli with conjugated oligoelectrolytes

Abstract

Conjugated oligoelectrolytes intercalate into and associate with membranes, thereby changing the surface charge of microbes, as determined by zeta potential measurements.

Membrane permeabilization by conjugated oligoelectrolytes accelerates whole-cell catalysis

“…It is worth pointing out that the maximum association of DSSN+ with E. coli, previously shown to be 20 nmol/OD 600 nm , is equivalent to a staining concentration of 12 mM in our experimental conditions. 32 These data thus suggest that little additional DSSN+ associates with cells above 10 mM, causing only a minor additional impact on OM permeability. Additionally, the OM permeability increases rapidly over the rst 4 h of staining, then tapers for all DSSN+ concentrations.…”

“…56 It is also important to note that COEs alter the physiochemical properties of the cell in a manner that may affect cell-electrode interactions. 32 Thus we cannot rule out that DSSN+ improves E. coli MFC performance through a combination of effects, such as increased permeability and cell attachment.…”

“…This limiting value reinforces the idea that permeability changes are proportional the amount of DSSN+ associated with the cell. 32 A comparison of these turnover rates (Table 1) shows that DSSN+ stained cells hydrolyzed ONPG up to 2-fold more rapidly than unstained cells. This 2-fold increase in turnover does not match with the 20-fold increase in OM permeabilization, indicating a different rate limiting process may be occurring.…”

“…8,11 Chemical and physical methods have been developed to increase membrane permeability and accelerate reaction rates despite possible complications in downstream processing, added processing steps, and excessive membrane damage or lysis. 8,12 While genetic modi-cations can also improve permeability, they are oen more effective at enhancing transport across the IM than the OM and are complicated to implement alongside other genetic modi-cations, such as enzyme overexpression. 13 Thus, there is a paucity of well-characterized, one-step methods for altering membrane permeability that do not introduce additional limitations.…”

“…13 To add to mechanistic complexity, recent results suggest that COEs may interact with other components in the cell envelope, such as lipopolysaccharides and cholic acid. [31][32][33] The degree to which such processes dominate bioelectrochemical changes, relative to electron transfer mechanisms, is not entirely known. Regardless, it is generally acknowledged that the ability of COEs to spontaneously intercalate in the membrane underlies their ability to increase charge transfer in bioelectrochemical devices.…”