Table 1.
Bacteria from Bacteroidetes phylum with culture conditions and previous mentions of iridescence.
Table 2.
Iridescence phenomenon of strains belonging to the Bacteroidetes phylum.
Figure 1.
Iridescence colors of Bacteroidetes.
Iridescence was observed after 24 h of growth (or 48 h for Z. uliginosa and P. gondwanensis) on CYT medium (A, B, C), for marine strains, or CY medium (D) for terrestrial strains.
Figure 2.
Spectral properties of the different glitter-like iridescence profiles.
The color maps show the angle-dependent spectral reflectance of Cellulophaga spp. colonies grown 24 h on different media. Samples were illuminated at a fixed light angle of −70°. Scattered wavelengths from 300 nm to 850 nm were recorded at different detection angles from −65° to 70° with 5° angle step resolution. Results are shown using a color intensity scale. As shown in the small inserts (upper left in each color map), iridescence profiles correspond to: (A) green and red iridescence profile with high intensity from C. lytica DSM 2040, moderate intensity from C. lytica CECT 8139, and low intensity from C. lytica DSM 7489; (B) other color profiles with green profile from C. lytica DSM 2040 on LN, yellow profile from C. lytica DSM 2039 and red iridescence profile from C. baltica CIP 106307; (C) non-iridescent controls with C. lytica CIP 103822, C. lytica CECT 8139 on sNA and the CYT agar control. Wavelength values: UV, <400 nm; violet, 400 to 435 nm; blue, 435 to 490 nm; cyan, 490 to 520 nm; green, 520 to 560 nm; yellow, 560 to 590 nm; orange, 590 to 620 nm; red, 620 to 700 nm; and infrared, >700 nm.
Figure 3.
Edges patterns of Bacteroidetes colonies.
Marine bacteria (A, B) and terrestrial bacteria (C) were grown 24 h on CYT and CY media, respectively. In (A), pictures of the entire colonies of C. lytica CECT 8139 and its mutant (impaired in gliding motility) are shown for comparison at the macroscopic level. The mutant was not iridescent on SYP, CYT, LN and sNA culture media (data not shown). All iridescent colonies exhibited typical spreading and jagged edges. Iridescent strains were: C. lytica CECT 8139 and DSM 2040 (and to a lesser extent DSM 7489), C. baltica CIP 106307, C. fucicola CIP 106308, C. pacifica LMG 21938, C. geojensis CCUG 60801, C. tyrosinoxydans DSM 21164, M. dokdonensis DSM 1720, F. johnsoniae DSM 2064, F. succinicans DSM 4002 and S. cauliformis DSM 3657.
Table 3.
Gliding motility and iridescence on CYT or CY media.
Figure 4.
Phase contrast observation of colony edges of different C. lytica strains at high magnifications.
Iridescent C. lytica CECT 8139 growing on CYT was observed at different colony positions: an edge (a) and an extreme edge (b). Low or non-iridescent conditions were CECT 8139 gliding defective mutant on CYT, C. lytica CECT 8139 grown on sNA and CIP 103822 strains grown on CYT. Magnification was ×400 (left column) and ×1000 (right column).
Figure 5.
Dynamic formation of iridescence.
A glitter centre (black arrow) was observed on the edges of a C. lytica DSM 2040 colony after 24 h incubation on CYT medium. Colony was photographed every 5 min for 60 min. Scales bars (A) 0.5 mm and (B) 0.1 mm.