When bacteria grow as colonies on agar, most form circular forms that are cream or off-white in colour. An occasional bacterial species though will grow as a vividly coloured colony. In 2016, I collected a unique palette (16 different bacteria) of living bacterial colour (see images below) which were used by artist JoWonder to paint an interpretation of John Millais’ famous pre-Raphaelite painting “Ophelia”.
As a source of natural colour there is an obvious link to the use of these bacteria in other art and design speculations where colour is important, for example in their use to provide textile designs or dyes for clothing. What is not often appreciated here though, is that these bacterial pigments aren’t just simple replacements for synthetic dyes, because bacteria produce these chemicals for other purposes, and they just accidentally happen to be colourful to our eyes. In this sense then, these bacterially generated compounds offer far more than just colour to the world of materials and textiles. Yes, they do provide vivid colour but they can also imbue materials with additional functionalities far beyond what conventional synthetic dyes offer. I’ve called this BioFunctionality, and an example of this concept follows.
Kocuria rhizophila, formerly known as Micrococcus luteus, is a very common yellow pigmented human skin inhabitant that has adapted to be able to survive in this unexpectedly harsh environment.
Like human skin is, bacteria are also susceptible to the damaging effects of Ultraviolet light (UV) and so exposed to sunlight on a daily basis K. rhizophila synthesises a pigment that absorbs wavelengths of light from 350 to 475 nm. This pigment then absorbs damaging UV light and protects this bacterium from its bactericidal effects. Exposure to these wavelengths of UV, commonly referred to as UVA, has also been correlated with an increased incidence of skin cancer, and so textiles dyed with this bacterium, in addition to being a vivid yellow would possess a BioFunctional sunscreen that would protect the wearer against UVA. Coming soon a BioFunctional and yellow tee-shirt for summer………