Organization of genes associated with 2-MIB biosynthesis in different organisms.

<p>The grayed, oblique-line, filled and opened arrows indicate <i>cnb</i>, <i>mtf</i>, <i>mic</i> and other predicted functional genes respectively.</p

Transcriptional changes in 2-MIB genes under darkness.

<p>The levels of <i>mtf</i> and <i>mic</i> expression under 72 h darkness were calculated relative to the expression in control culture (light density as 30 µmol photons·m⁻²·s⁻¹).</p

Biosynthesis pathways of 2-MIB in actinomycetes.

<p>Geranyl pyrophosohate (GPP), the universal precursor of monoterpenes, is converted to 2-MIB through two steps: methylation of GPP and cyclization of methyl-GPP subsequently.</p

GC-MS analysis of volatile compounds obtained from the gaseous phase of the <i>Pseudanabaena</i> sp. dqh15 culture.

<p>Mass spectrum revealed that the main volatile compound (retenion time as 11.64 min, m/z 168) is 2-MIB.</p

2-MIB biosynthesis associated genes identified from cyanobacterial strains.

<p>A: <i>Pseudanabaena</i> sp. dqh15; B: <i>Planktothricoides raciborskii</i> CHAB 3331. The <i>cnb</i>, <i>mtf</i> and <i>mic</i> reprents cyclic nucleotide-binding protein gene, methyltransferase gene and 2-MIB cyclase gene respectively. These genes form putative operon in chromosome.</p

Alignment of amino acid sequences of 2-MIB cyclases.

<p>Mic-PS and Mic-PL representing proteins from <i>Pseudanabaena</i> sp. dqh15 and <i>Planktothricoides raciborskii</i> CHAB 3331 respectively; Sco7700, Sgr1269, Scab5041, Ndas2620, Caci4612, and Snas1991 represent proteins from <i>Streptomyces coelicolor</i> A3(2) (AL93912), <i>S. griseus</i> NBRC 13350 (AP009493), <i>S. scabiei</i> 87.22 (FN554889), <i>Nocardiopsis dassonvillei</i> DSM 43111 (CP002040), <i>Catenulispora acidiphila</i> DSM 44928 (CP001700), and <i>Stackebrandtia nassauensis</i> DSM 44728 (CP001778), respectively. Black boxed residues show the possible Mg²⁺ binding sites; sites marked by * and # at the bottom indicate putative substrate binding pockets and active site lid residues respectively.</p

Expression changes of 2-MIB associated genes under different light intensities.

<p>The levels of <i>mtf</i> and <i>mic</i> expression in different light density (10 and 60 µmol photons·m⁻²·s⁻¹) were calculated relative to the expression in control culture (30 µmol photons·m⁻²·s⁻¹).</p

Unrooted neighbor-joining (NJ) phylogenetic trees of 2-MIB associated genes.

<p>A: The phylogenetic tree based on putative <i>mic</i> genes; B: The tree based on <i>mtf</i> genes; C: The tree based on <i>cnb</i> genes. Bootstrap values (>50%) are displayed at the nodes. Accession numbers: <i>Am. mediterranei</i> U32 (CP002000); <i>Ca. acidiphila</i> DSM 44928 (CP001700); <i>No. dassonvillei</i> DSM 43111 (CP002040); <i>P. fluorescens</i> Pf0-1 (CP000094); <i>Sa. erythraea</i> NRRL2338 (AM420293); <i>St. nassauensis</i> DSM 44728 (CP001778); <i>S. ambofaciens</i> ATCC 23877 (AM238663); <i>S. bingchenggensis</i> BCW-1 (CP002047); <i>S. coelicolor</i> A3(2) (AL939132); <i>S. griseus</i> NBRC 13350 (AP009493); <i>S. lasaliensis</i> ATCC 31180 (AB547324); <i>S. scabiei</i> 87.22 (FN554889); <i>Cyanothece</i> sp. PCC 7424 (CP001291); <i>Cyanothece</i> sp. PCC 7425 (CP001344).</p