%0 Journal Article %A Waters, Paul %A Lloyd, David %T Salt, pH and Temperature Dependencies of Growth and Bioluminescence of Three Species of Luminous Bacteria Analysed on Gradient Plates %D 1985 %J Microbiology, %V 131 %N 11 %P 2865-2869 %@ 1465-2080 %R https://doi.org/10.1099/00221287-131-11-2865 %I Microbiology Society, %X Summary: Two-dimensional diffusion gradients (of NaCl and H+ concentrations) were established in solid growth medium containing glycerol and yeast extract as major carbon sources. These were used to investigate conditions favourable for growth and bioluminescence of three species of luminous bacteria during incubation at different temperatures. Photobacterium leiognathi, Photobacterium phosphoreum and Vibrio fischeri all grew over the entire salt range used [0.9–3% (w/v) NaCl] and at pH values < 7 at the most favourable temperatures (20 °C, 20 °C and 15 °C respectively); upper and lower temperature limits for growth over a 72 h period were 30 and 10, 25 and 5, and 30 and 5 °C respectively. Bioluminescence was observed at all temperatures that supported growth; in P. leiognathi emission at 10 °C was hardly detectable even after 72 h, but at higher temperatures it occurred at all NaCl concentrations. Low pH values and high NaCl concentrations favoured luminescence in the other two organisms; after 48 h light emission decreased from the high pH and low NaCl regions of the gels. These results are discussed with reference to the symbiotic (P. leiognathi, V. fisheri) or free-living (P. phosphoreum) origins of the organisms studied. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-131-11-2865