88 PART V The Part of Tens
It’s quite amazing! Did you know that there are 10 times more bacteria
in our guts than cells in our entire body?
You need:
✔✔Yogurt with active cultures
✔✔A glass slide with coverslip
✔✔A Q-tip or toothpick
✔✔Methylene blue (optional)
✔✔Gloves (optional)
You only need a small amount of yogurt, so enjoy the rest. Smear a
tiny probe with the toothpick on the slide. If you have methylene blue
available, place a small drop of the solution on the slide. Wear gloves
and do not allow children to handle methylene blue solution be-
cause of its toxicity. Place the coverslip on the slide and have a look
with your microscope using the lowest magnification first. Bacteria
will appear small even at the highest magnification, and you can see
some of the typical species used for yoghurt cultures:
✔✔Lactobacillus delbrueckii (rod shaped)
✔✔Lactobacillus acidophilus or casei
✔✔Streptococcus salivarius (sphere shaped)
✔✔Bifidobacterium bifidus (rod shaped, often branched bacteria)
Pond Water Habitats
Looking for a nice swim? Be aware that there are a lot of little fellows living in
ponds and puddles. The dirtier the water appears, the more fascinating it becomes
under the microscope. You can determine the water quality of a lake by hav-
ing a look at the planktonic organisms present.