Unusual mould

Petri dish with unusual mould

My colleague David C recently posted an image of Bernard convection cells in a conical flask noticed by an HND Chemistry student. That was one occasion when a mobile phone with a good camera came in very useful!

One of our technicians came up with the Petri dish illustrated here – showing a black fine structured mould that seems to be growing in perfect concentric circles. The general feeling is that the mould grows in cycles, and perhaps produces a toxin after a period of growth that kills off the mould cells in the clear circles. Most of the deliberately exposed Petri dishes had ‘normal’ green mould of the kind you see on bread left in a warm room for too long. Only this dish had the finer structured ‘rust’ like mould with the circular growth pattern.

Pictures: We rigged up an improvised light box using an overhead projector, some paper and a ruler for scale. My basic snapshot digital camera has a ‘macro’ mode, and the detailed shot here is cropped from the full 1600 by 1200 frame. The camera was handheld.

mould in concentric circles - detail

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