Rings - take 3
Juan Pablo Gomez-Escribano, John Innes Centre
Most of the compounds we use as antibiotics, or that we transform into useful antibiotics, are obtained from soil-dwelling microbes called actinomycetes. These bacteria grow as filaments on a solid substrate. When the environmental conditions are adequate, part of the filaments grow into the air and develop into spores, tiny but strong reproductive structures that can persist even under very tough conditions (very high or very low temperature, complete dryness).
In this macro-photograph of some colonies of the actinomycete Streptomyces coelicolor, you can see the lawn of thin white filaments extending outside the colony. This microbe produces several coloured antibiotics, two of them are the blue actinorhodin and the red prodigiosine and in these colonies they form beautiful rings as the colony develops and grows on a nutritious substrate.