streak plate?

Question

why it is important to avoid ploughing up the surface of the agar when inoculating?....why have to invert the dishes when they incubated?

Answer 1

The gouges in the agar just make trying to pick any colony which grows in that area more difficult. Additionally, you might cultivate an anaerobic bacterium under the agar, rather than just having aerobic or aerotolerant organisms on the surface. You invert the dishes so that drops of condensation from the lid don't drop onto the surface of the agar and allow colonies to mix.