Archive for the ‘microbiology’ Category

Acetone Yoghurt

November 3, 2010

My favourite breakfast had a bit of spritz about it but it wasn’t out of date. I like my passionfruit yoghurt but did wonder why it seemed a bit lively and tangy this one morning. The following day I was crook with a cold which lingered and so did not have my ‘normal’ breakfast for a week or so. But then, when I cranked out the large tub of favourite yoghurt (still not past it’s use by date) I was overpowered by the acetone smell that emerged. The concentration must have been high as it smelt stronger even than a close up whiff of nail polish remover.

I read a bit online about bacteriological produced acetone. Clostridium acetobutylicum, the most well documented, is sometimes called the “Weizmann Organism”, after Chaim Weizmann, who in 1916 helped discover how C. acetobutylicum culture could be used to produce acetone, butanol, and ethanol from starch using the ‘Acetone Butanol Ethanol process’.

Still this organism seemed a little unlikely in this case as it produces acetone et al in anaerobic conditions, and a tub of yoghurt in the fridge at 4 degrees C didn’t seem like the ideal conditions for acetone production. I froze a sample on the off chance it might be useful later and streaked the yoghurt on nutrient agar in an effort to isolate the relevant organism. Clearly I will have to isolate it from the Lactobacillus and Streptococcus species I expect to find in the yoghurt. I wonder if this is a well known bacteria? I will update if I can identify it.