Antimicrobial+action+of+nutritives

Pick an herbal 'medicine' that helps with a bacterial condition (or even not) or a common house plant and test its effectivness in controlling bacterial or fungal growth. Easy to do. However, it seems unlikely that there would be a hit.

Could do the same thing with simple extracts from household plants and common garden plants. Ethanolic extracts or even boiling water extracts can be concentrated and then disk diffusion assays performed.

The place to start is by searching PubMed, or perhaps more easily Google Scholar using the scientific names of common houseplants and garden plants and keywords such as antibacterial, antifungal, and antimicrobial. Surprisingly, most plants that I searched already had some studies done on them. But I found several that either didn't have anything (and hence no pub) or haven't been looked at. For instance, I did not find anything for the jade plant.

Another avenue for adventure is to look at parts of the plant not examined. Most of the studies I've seen are for leaves, flowers, seeds, and some bark. Pretty sure that roots were not examined. The soil is a complex system of chemical warfare, and roots surely have to defend themselves. Marigolds produce a variety of thiophenes (5-membered ring with a nitrogen) to kill nematodes. Roots are hard to wash very well and there is a chance that plants grown in sand, won't be stimulated to produce defense compounds.

A similar twist is to revisit common plants that have been examined for antibacterials let's say, and then look for effects on something different such as algae or protozoans.