PSYCHROPHILIC GLUCOSE MINERALIZATION IN LAKE-SEDIMENTS DURING WINTER

Glucose mineralization rates were measured at 4°C and 18°C in sediment samples taken during ice-cover from an oligotrophic lake and a eutrophic lake and were found to fit Michaelis-Menten kinetics. Turnover times for glucose mineralization were 20.7 h and 2.6 h at 4 and 18°C, respectively, for the oligotrophic lake, and 26.2 and 5.4 h at 4 and 18°C, respectively, for the eutrophic lake. Vmax values, in units of μg/h/viable cell, were 5.0 × 10-6 and 6.0 × 10-6 at 4 and 18°C, respectively, for the oligotrophic lake, and 1.2 × 10-5 and 3.9 × 10-5 at 4 and 18°C, respectively, for the eutrophic lake. The implications concerning the contribution of psychrophiles to mineralization activity and how well temperature adapted the sediment bacteria are, are discussed. © 1979.