Secondary electron micrographs of rubber-degrading strains on synthetic cis-1,4-polyisoprene (IR). Shown are the noninoculated control (A), growth of Gordonia sp. strain VH2 after 4 days (B) and after 1 week (C), growth of M. fortuitum NF4 after 1 week (D), and the growth of M. aurantiaca W2b after 1 (E) and 4 (F) weeks. Bars, 5 μm (A, B, D to F) and 50 μm (C).