Bacteriology of manganese nodules. V. Effect of hydrostatic pressure on bacterial oxidation of MnII and reduction of MnO2.

It was experimentally demonstrated that two strains of Arthrobacter 37, one growing at 25 C and the other at 5 C, could catalyze Mn(II) oxidation at hydrostatic pressures well in excess of the pressure encountered by the parent culture in its original habitat in the ocean (80 atm). The strain grown at 5 C showed an increase in temperature optimum for manganese oxidation with increase in pressure. It was like-wise experimentally shown that induced Bacillus 29 without added ferricyanide and uninduced Bacillus 29 with added ferricyanide could catalyze MnO(2) reduction at hydrostatic pressures in excess of the pressure encountered by this organism in its original habitat (187 atm). The uninduced Bacillus 29, in the presence of ferricyanide, was active over a wider range of pressures (1 to 1,000 atm) than the induced Bacillus 29 in the absence of ferricyanide (1 to 467 atm). At corresponding pressures, the uninduced culture was also considerably more active than the induced culture. Special techniques were developed for measuring Mn(II)-oxidizing and MnO(2)-reducing activity under pressure.