Inter-strain bioluminescence induction in mixed and spatially separated <i>arcA</i>⁺ and <i>arcA</i> mutant cells.

<p>Wild-type cells were mixed with either the dark <i>arcA</i> Δ<i>luxCDABEG</i> strain (JB33) able to produce 3OC6 (A) or the dark <i>arcA</i> Δ<i>luxICDABEG</i> strain (ANS6) lacking the <i>luxI</i> 3OC6 synthase gene (B). Wild-type and <i>arcA</i> mutant cultures and co-cultures were grown in SWTO broth in duplicate aerobic shake flasks to peak luminescence. A sample was removed and dilution plated to determine the CFU ml⁻¹ and the percent of wild-type cells in each co-culture (52% for A, 68% for B). Luminescence values are presented as luminescence per 10⁸ CFU. Luminescence values presented for co-cultures are luminescence per 10⁸ wild-type CFU. (C) Cultures of wild type or the <i>luxI</i> mutant were streaked onto SWTO agar plates next to spotted culture of the dark <i>arcA</i> Δ<i>luxCDABEG</i> strain (JB33) able to produce 3OC6. Inoculated plates were incubated at room temperature overnight and negative images of bioluminescence were captured with a BioRad Fluor-S MultiImager. Scale bar indicates approximately 5 mm.