Glucose mineralization activity and the use of the heterotrophic activity method in an acidified lake

This paper concerns bacterial glucose mineralization in Silver Lake sampled during the summer; specifically, whether or not it occurs, and whether or not the “heterotrophic activity method” can be used to measure it, in this acidified lake.For Sampling I, linearity between turnover time (t/f) and added substrate concentration (A) did not exist at the in situ pH (3.2) or the experimental pH's (5.5 and 7.0), even though time studies showed that glucose was being mineralized at measurable rates. For Sampling II, modifications were made to the concentrations of labelled glucose and the incubation time. A highly significant linear relationship between t/f and A was demonstrated, and the turnover time and V_max were calculated to be 472.3 h and 0.005 μm l⁻¹ h⁻¹, respectively. For Sampling III, even though the environmental conditions were similar to those for the previous sampling, a statistically-significant relationship between t/f and A did not result.