Competitive Inhibition for Amino Acid Uptake by the Indigenous Microflora of Upper Klamath Lake

ABSTRACT

The uptake of a specific ¹⁴C-amino acid by the heterotrophic microorganisms in the epilimnion of an eutrophic lake was influenced by the presence of other amino acids. The effect of unlabeled serine on ¹⁴C-glycine uptake was shown to be caused by competitive inhibition, which changed the interpretation of the kinetic parameters, the turnover time, T_t, and the sum of a transport constant, (K_t + (S_n), and the natural substrate concentration. The maximum velocity of uptake, V_max, is unaffected by the competitive inhibition.