Comment on "Computational improvements reveal great bacterial diversity and high metal toxicity in soil".

Based on analysis of the reassociation kinetics of bacterial DNA in soil, Gans et al. (Reports, 26 August 2005, p. 1387) claimed that millions of microbe species existed in 10 grams of pristine soil and that 99.9% of the diversity was lost as a result of toxic metals. We show that the data do not support these startling conclusions unambiguously.