Table 4. Supplementation of bacterial biofilms with catalase, D-mannitol or Tempol protects against the electricidal effect.

Antioxidant	Concentration of Antioxidant	S. aureus ΔLRF	S. epidermidis ΔLRF	P. aeruginosa ΔLRF
Catalase 200 μA	500 U/ml in biofilm	0.75*	0.62	0.79
	200 U/ml in buffer	0.85*	0.82	0.3
	500 U/ml in buffer	1.18*	1.1	0.82
Mannitol 200 μA	20 mM in biofilm	0.28	0.09	-0.29
	20 mM in buffer	-0.82	0.47	0.79
	50 mM in buffer	-0.78	0.58	0.8
Tempol 200 μA	5mM in biofilm/1 mM in buffer	-0.42	0.32	0.2
	10mM in biofilm/1 mM in buffer	0.12	1.59**	0.33
Tempol 20 μA	5mM in biofilm/1 mM in buffer	ND	ND	0.95
	10mM in biofilm/1 mM in buffer	ND	ND	2.10**

Bacterial biofilms were exposed to 200 μA direct current. A positive number indicates protection; bold font indicates a greater than 0.5 decrease in LRF. ND = Not determined

*p = 0.0463

**p = 0.0495, n = 3 for all samples.