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Christmas spores. Merry Christmas from the REACT team

By Christina Julius

When we think about bacteria, we tend to think of spoiled food and illness. But not all bacteria are bad- they are the most diverse organisms on the planet!  They are important for a range of biochemical processes, such as helping cattle to digest grass and producing cheese from milk. To study bacteria, we can grow bacteria into colonies on plates containing a media (agar) of essential nutrients and chemicals.  We can also use bacteria to make some fascinating and festive images to wish you all a Merry Christmas.

For making these images I had a lot of help finding strains and media. I want to thank all my colleagues at CBCB (Newcastle University)- especially Yulia Yuzenkova, Amber Riaz-Bradley, Charles Winterhalter, Kaveh Emami, Fernando Santos Beneit, Valeria Verrone and Olga Chrobak.

The bacteria behind the photos

1. Christmas Tree: Synechocystis sp. PCC 6803. Cyanobacteria are usually green due to photosynthesis but here it seems that the presence of a lot of glucose (food) lead the strain to turn slightly yellow.
Christmas Baubles:  Streptomyces spp. Streptomyces are actinobacteria and the natural source of many antibiotics e.g. streptomycin, tetracycline or chloramphenicol.

2. Merry Christmas: E. coli MG1655. E. coli is the most commonly used model organism in microbiology.
Stars: E. coli MG25113. This strain is genetically altered and contains GFP (green fluorescent protein). The addition of arabinose induces the expression of GFP.

3. Snowman: Streptomyces coelicolor M145. This Streptomyces produces the antibiotic actinorhodin which diffuses into the agar and dyes it blue. At prolonged incubation, the cells will start to produce spores as a survival mechanism, which would turn the snowman white.

4. Small Christmas Tree: Klebsiella pneumoniae. An opportunistic pathogen that causes urinary or respiratory tract infections and is often transmitted via hospital equipment or staff. Many strains also have a multitude of antibiotic resistances. The patients from which the strains were isolated suffered from reoccurring bacteremia (blood infection).
Christmas baubles: E. coli.The strain here is not a model organism from the lab but a blood isolate from the hospital. Some pathogenic strains of the otherwise harmless species E.coli can cause very severe conditions. Often they are multi-resistant.

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