Oxygen isotope fractionation during respiration for different temperatures ofT. utilis andE. coli K12

Summary The temperature dependence of the oxygen isotope fractionation factor during respiration has been examined for two different microorganisms, namelyTorulopsis utilis andEscherichia coli K12 representing a yeast and a bacterium, respectively. The investigation covered a temperature range of 18° C, that is from 16° C to 34° C forT. utilis and from 19° C to 37° C forE. coli K12. Within this temperature range the fractionation factor ofT. utilis increases by 0.18; an insignificant change ( _{10° C} = 0.063;r = 0.067), whereas withE. coli K 12 an increase of 1.12; has been observed ( _{10° C} = 0.6;r = 0.55).