Sniffing Petrol

Science isn’t just about pouring colourful liquids between test tubes. Sometimes your experiments are bizarre and fun — more often they’re tedious and require more focus than you knew you had. Below are the weirder technologies that researchers used to work out why bacteria make geosmin.

How to collect the volatile chemicals bacteria produce as they grow.

How do you show that your bacteria are making geosmin?

1. Take another of your agar plates and grow your bacteria.
2. Put your plate in a Toppits®️ cooking bag — yes, really — and seal it airtight.
3. Make two holes in your bag — one to blow filtered air in, and another to suck the air out through a filter which will capture chemicals your bacteria give off. Leave it for a day.
4. Remove your capture filter and rinse it in heptane, one of the major components of petrol.
5. The heptane will dissolve the chemicals your bacteria produced, which you can analyse to detect geosmin.