  We discuss the perturbative running of alpha_s in a model independent way.
Our analysis contains data on the hadronic tau decay and hadronic cross
sections in e+e- annihilation between 5 GeV and M_Z. We determine the color
coefficients and the perturbative beta-function of the strong interaction. The
results are in agreement with QCD and rule out the QCD+light gluino scenarios
on the 70.8 - 93.0% CL. We combine our method with that of the multi-jet
analysis at LEP. The combined result rules out light gluinos at least on the
99.76% CL, provided that nonperturbative effects are not large.
