Fig. 7From: Investigation of the optimum conditions for electricity generation by haloalkaliphilic archaeon Natrialba sp. GHMN55 using the Plackett–Burman design: single and stacked MFCsThe microbial fuel cell units of the Plackett–Burman design (a); single microbial fuel cell without a mediator (b); and single microbial fuel cell with a mediator (c)Back to article page