EFFECT OF FERMENTATION CONDITIONS ON N-2 FIXATION BY METHYLOCOCCUS-CAPSULATUS

Nitrogen fixation has been investigated during chemostat fermentations with a culture of Methylococcus capsulatus with natural gas. It is de monstrated that nitrogen fixation occurs under conditions when either nitrate or ammonia as nitrogen source is insufficient for the growth o n fixed supply of methane and oxygen. The fixation occurs contrary to expectations within a wide range of dilution rates and with variation of concentration of liquid source of nitrogen. An O-2 optimum is deter mined for the nitrogenase system of the culture in an assay. During fe rmentation a complete abolishment of nitrogenase reaction is attained at 15% air saturation (dissolved oxygen). Conditions for N-2 fixation is unaltered with change of pH from 6.8 to 5.7.