Influence onEuglena gracilis of three types of inhibitors

Three groups of antibiotics were established according to their mechanism of action on the incorporation of¹⁴C-labelled precursors inEuglena gracilis:1. antibiotics markedly inhibiting nucleic acid synthesis and negligibly affecting protein synthesis and inducing permanently bleachedE. gracilis; 2. antibiotics markedly inhibiting protein synthesis and only moderately nucleic acid synthesis and not causing permanent bleaching ofE. gracilis; 3. compounds inhibiting both protein synthesis and nucleic acid synthesis to a similar degree, some of them bringing about permanent bleaching ofE. gracilis. Nitrofurantoin was comparable to compounds of the first group, sodium azide to those of the third group. Both exhibited 100 % bleaching ofE. gracilis, although with the latter this occurred only after a short-term increase of the incubation temperature from 25 to 37 °C.