Figure 1: Light-driven pump activity of Krokinobacter eikastus.

(a) Light-induced pump activity in native K. eikastus cell suspensions containing 100 mM NaCl is measured using a pH electrode (top; black lines). Cells are collected at 10, 48 and 96 h in the growth phase (bottom). Red and blue lines show the pump activities measured after the addition of CCCP and CCCP+TPP⁺, respectively. (b) Phylogenetic tree of microbial rhodopsins’ amino-acid sequences. KR1 and KR2 are indicated by red circles.