Microbial art

Microbial art, agar art, or germ art is artwork created by culturing microorganisms in certain patterns. The microbes used can be bacteria, yeast, fungi, or less commonly, protists. The microbes can be chosen for their natural colours, or can be engineered to express fluorescent proteins and viewed under ultraviolet light to make them fluoresce in colour. Agar plates are used as a canvas, while pigmented or fluorescent bacteria and yeasts represent the paint. In order to preserve a piece of microbial art after a sufficient incubation, the microbe culture is sealed with epoxy. Microbe species can be chosen for their natural colours to form a palette for the artwork. Suitable species of bacteria (with their colours) include Bacillus subtilis (cream to brown), Chromobacterium violaceum (violet), Escherichia coli (colourless), Micrococcus luteus (yellow), Micrococcus roseus (pink), Proteus mirabilis, Pseudomonas aeruginosa (brown), Pseudomonas fluorescens (naturally blue-green fluorescent with pyoverdine), Serratia marcescens (pink or orange), Staphylococcus aureus (yellow), and Vibrio fischeri (bioluminescent). Yeast species – which are fungi – used include Saccharomyces cerevisiae (yellow-white) Aspergillus flavus (yellow-green spores), Aspergillus ochraceus (yellow), Aureobasidium pullulans (black), Candida albicans (whitish buff), Candida sake, Candida sp. (whitish), Cladosporium herbarum (brown to black), Cladosporium resinae, Epicoccum nigrum (yellow, orange, red, brown, and black), Fusarium sp., Rhodotorula sp., and Scopulariopsis brevicaulis. Protist species used include Euglena gracilis (photosynthetic, green) and Physarum polycephalum (yellow-green). A technique called "bacteriography" involves selectively killing certain areas of a bacterial culture with radiation, in order to produce artistic patterns. After incubation, the culture is sealed with acrylic. The type of medium in the agar plates is also important. Chromagar Candida is a differential medium that is used to identify different Candida species.