Introduction I II 2000 2000 2001 III 2002 1993 1999 Escherichia coli E. coli 2000 Streptomyces aeriouvifer 1996 Bacillus subtilis, 2000 E. coli 2004 1 IV d V d VI 1997 1998 d 1978 1981 1982 1989 VI C d 1998 1 Fig. 1 d C d C d C d C d C d italics YpgA  1995 B. subtilis B. subtilis B. subtilis B. subtilis 1995 B. subtilis 1999 B. subtilis 2000 2000 1998 2001 2005 B. subtilis 2002 B. subtilis E. coli B. subtilis Bacillus 2003 d 1984 1998 E. coli Saccharomyces cerevisiae 1999 2001 1997 2003 B. subtilis B. subtilis Bacillus Materials and methods Bacterial strains and media 1 B. subtilis B. subtilis 1998 d Table 1 B. subtilis E. coli Enzyme E. coli B. subtilis Essential gene Mutant strain Dxs (1) dxs dxs/yqiE + yqiE IspC/Dxr (2) dxr yluB + yluB IspD (3) ygbP yacM + yacM IspE (4) ychB yabH + yabH IspF (5) ygbB yacN + yacN IspG (6) gcpE yqfY + yqfY IspH (7) lytB yqfP + yqfP Idi I idi –  – Idi II (8) – ypgA a – ypgA IpsA/FPPS (9) ispA yqiD + yqiD a Streptomyces 2001 Detection of bacterial isoprene emission B. subtilis 2000 600 nm Results Bacillus B. subtilis 3 2 B. subtilis B. subtilis 3 600 nm 3 600 nm B. subtilis 3 600 nm 3 600 nm 2 Fig. 2 B. subtilis B. subtilis  Table 2 Bacillus subtilis 600 nm Bacillus subtilis 600 nm 168 149 6051 166 23059 192 23856 111 Mutant strains 3 yqfY B. subtilis Table 3 Bacillus 600 nm Bacillus Limited expression (μM IPTG) 600 nm Relative decrease Limited induction Full induction Full repression yqiE 10 8 119 27 15.2 yluB 1 31 167 13 5.4 yacM 50 4 113 4 27.9 yabH 25 29 160 7 5.6 yacN 10 14 119 20 8.8 yqfY – n.d. 194 147 – yqfP 1 13 130 17 9.8 ypgA – – – 103 – yqiD 10 122 166 139 1.4 The relative decrease is calculated as the maximal amount of isoprene at full induction devided by the maximal amount of isoprene at limited induction (dashes indicate that measurement did not apply here; explained in detail in the text, with numbering of the respective enzymatic steps). n.d. For all conditional knock out strains isoprene emission was measured at the concentration of IPTG with limited expression in comparison to 1 mM (full induction) and no IPTG (full repression). 3 yqiE dxs B. subtilis 3 600 nm 3 600 nm Fig. 3 B. subtilis  3 yluB yacM yabH yacN yqfP ypgA B. subtilis yqiD 7 E. coli Discussion B. subtilis 1995 B. subtilis 1997 B. subtilis B. subtilis B. subtilis 1995 B. subtilis B. subtilis yqiE yqiE dxs d B. subtilis 1999 2001 2006 1998 1998 yluB yacM yabH yacN yqfP B. subtilis yqfY 2006 ypgA B. subtilis ypgA 2004 E. coli 1999 2000 ypgA B. subtilis 2004 idiI E. coli 1999 ypgA 2004 2004 yqiD B. subtilis yluB yacM yabH yacN yqfP, yqfY B. subtilis E. coli 2003 2006 2006 2006 B. subtilis