When the aerobic incubations of symbionts were made
anaerobic and vice versa, the nitrate respiration rates adjusted
to the new incubation conditions after a lag of about 20 min
(Fig. 1). Symbiont respiration clearly does not come to an
immediate halt, as has been documented for Escherichia coli
(12) and Pseudomonas spp. (2, 11). If electron transport to
oxygen is not present in the symbiont respiratory chain, then
the electron flow cannot be redirected to cytochrome oxidase.
A time lag would be expected