The term that best describes heterotrophic bacteria that feed on dead organic matter is saprotrophs.

Here's why:

* Heterotrophic: This means they obtain their nutrients from consuming other organisms.

* Saprotrophic: This specifically refers to organisms that obtain their nutrients from dead organic matter.

So, saprotrophs are a type of heterotroph that specialize in breaking down dead plants and animals, playing a crucial role in decomposition and recycling nutrients in ecosystems.