Rings - take 1
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 a colony of the actinomycete Streptomyces coelicolor, you can see the lawn of thin white filaments over which drops of water have condensed. A ring of the blue antibiotic made by this microbe is spreading on the edge of the colony.