Oxygen isotope fractionation during respiration for different temperatures of T. utilis and E. coli K12.

The temperature dependence of the oxygen isotope fractionation factor during respiration has been examined for two different microorganisms, namely Torulopsis utilis and Escherichia coli K12 representing a yeast and a bacterium, respectively. The investigation covered a temperature range of 18 degrees C, that is from 16 degrees C to 34 degrees C for T. utilis and from 19 degrees C to 37 degrees C for E. coli K12. Within this temperature range the fractionation factor of T. utilis increases by 0.18% an insignificant change (delta delta 10 degrees C = 0.063%; r = 0.067), whereas with E. coli K12 an increase of 1.12% has been observed (delta delta 10 degrees C = 0.6%; r = 0.55).