EFFECT OF CULTURE-MEDIUM IONS ON CHROMATE REDUCTION BY RESTING CELLS OF AGROBACTERIUM-RADIOBACTER

The influence of some ions in pre-growth culture medium on chromate re duction by resting cells of Agrobacterium radiobacter strain EPS-916 w as investigated. The reduction was dependent on the Fe2+ content of th e culture medium: the higher the iron content, the lower the reduction rate. The cells showed maximum chromate reduction when pre-grown in t he presence of 0.243 muM Mg2+, 20 muM Ca2+ and 3.6 muM Mn2+ . Chromate reduction was not affected by the addition of MgCl2, CdCl2, ZnCl2, Mn Cl2, Na2SO4 (1000 muM), and Na2MoO4 (100 muM) to the activity assays. However, activity was inhibited by the presence of Na2SO4 (10 mM), Na2 MoO4 (200 muM) and ferric citrate.