How to feed bacteria out of lab
In a lab there are so many ways of doing this. However, at home is a little tricky. This is what I would do:

Keep your bacteria in a liquid media.

Liquid Media: make the media out of NaCl and AS CLEAN AS POSSIBLE (distilled if possible) water (concentration 18g NaCl / L). Place a sample of the bacteria into the solution. Freeze solution with bacteria (-20 degrees C if possible). Take out when wanted.