GeoChip 2.0 was used to examine phenanthrene-spiked soil microcosms to examine the effect of phenanthrene on microbial communities (Ding et al., 2012) . Communities were examined after a 21-day incubation and compared with communities from day 0. A larger number of genes were detected in spiked soils compared to the control soils. Genes showing an increase in the spiked soils included dioxygenases involved in aromatic compound degradation, genes involved in the degradation of PAHs (nahA, rhda, nahQ, narR) , and genes involved in the degradation of one-ring aromatic compounds. In addition, an overall shift in community composition and structure was noted in spiked soils as determined by non-metric multidimensional scaling.