Question

You discover a unicellular organism in a pool in an abandoned salt mine. The organism has cell walls, but the walls do not contain peptidoglycan. The new organism is likely a species of bacteria.

True
False

Answer 1

False.

Bacteria characteristically have cell walls containing peptidoglycan. A unicellular organism with a cell wall that lacks peptidoglycan is much more likely an archaeon (e.g., halophilic Archaea with pseudomurein or S‑layer proteins), especially from an extreme salty environment.