KINETIC-STUDY ON THE MINERALIZATION OF LOW-MOLECULAR FATTY-ACIDS IN AN ANOXIC MARINE SEDIMENT

The mineralization Kinetics of low molecular fatty acids and glucose w ere investigated in the anoxic sediment of Uranouchi Inlet, Japan. The V-max values of mineralization of acetate, propionate, lactate, and g lucose were 0.30-2.68 nmol/g/h, 0.45-1.57 nmol/g/h, 1.34-3.68 nmol/g/h , and 0.47-1.86 nmol/g/h, respectively. Those of formate mineralizatio n were highest in all substrates tested, 90.8-637 nmol/g/h: 3 orders o f magnitude higher than the other compounds. Turnover time varied acco rding to substrate and temperature, ranging from 1.5-4.2 h for formate to up to 70 h for acetate without molybdate. The highest V-max values and shortest turnover time of fatty acids mineralization were recorde d in summer sediment samples. Thus, the anaerobic mineralization poten tial and turnover of fatty acids in the terminal steps of decompositio n of organic matter were higher in summer than winter, and were mainly affected by the temperature of the sediment. Furthermore, sulfate-red ucing bacteria accounted for a significant part of the mineralization potential and turnover.