Indole-producing bacteria from the biosynthetic organs of a muricid mollusc could contribute to tyrian purple production

The muricid mollusc Dicathais orbita produces Tyrian purple, which is a brominated derivative of the blue dye indigo. This study aimed to establish whether distinct bacterial communities occur in the organs of D. orbita associated with Tyrian purple production and to identify indole-producing bacteria using 16S rRNA sequencing. Biochemical profiles of microbial communities from different D. orbita tissues were investigated and the composition of aerobic heterotrophic bacterial populations from homogenates and swabs assessed. There were significant differences in biochemical activity profiles and bacterial communities cultured from different D. orbita tissues, but no significant differences between males and females. Bacterial communities derived from foot tissue and seawater samples were similar. The biochemical and molecular evidence from swabs and tissue homogenates suggest indole-producing isolates are Vibrio spp. This study suggests Tyrian purple indole precursors could be obtained from opportunistic ubiquitous bacteria.