Teachers discover that bacteria prefer milk chocolate

Bacteria prefer milk chocolate to dark chocolate and will swim towards it on an agar plate, so teachers have found out this week (15-19 July) at a summer school run by the Society for General Microbiology at the University of Reading. The experiment is one of a series of A-level practicals currently being produced for teachers by the Society.
“We have developed the chocolate experiment to show that bacteria can detect a food source and swim towards it – a process called chemotaxis. But we’ve seen that they are fussy eaters. They swim towards milk chocolate, but away from dark chocolate. The experiment is really visual because the bacterium we use, Janthinobacterium lividum, produces a bright purple pigment around the milk chocolate drop,” says Dr Liz Sockett from Nottingham University.

The week-long residential course has given 50 teachers from around Britain the chance to hear about new research in areas of microbiology that can tied to the A-level biology syllabus. Teachers have been brushing up on their practical microbiology techniques as well as listening to talks on bioethics, antibiotic resistance and vaccination.

The SGM provides a range of resources for teachers, including one-day workshops, basic practical microbiology manual, posters, briefing papers, and a dedicated website at www.microbiologyonline.org. Schools can also join the Society for £10 per year, which entitles them to advanced mailings of new resources, reduced rates to attend courses, and a quarterly copy of our award-winning house magazine Microbiology Today.