What is the difference between a bacterium and a fungus?
Question
The other day, our microbiology professor asked us to compare bacteria and fungi, and it got me thinking about how often we confuse the two. I remembered reading in Brock’s textbook how different their cell structures, reproduction, and even roles in nature are. This breakdown really helped me understand their unique features clearly—especially why antibiotics don’t work on fungi.
Answer ( 1 )
Cell type
Cell wall composition
Membrane lipids
Size and morphology
Bacteria are unicellular rods, cocci or spirals (0.5‑5 μm). Fungi can be unicellular yeasts (3‑10 μm) or multicellular molds with branching hyphae; some are dimorphic.
Reproduction
Bacteria divide by binary fission and exchange genes via plasmids or phages. Fungi reproduce by budding, fission or by forming sexual and asexual spores.
Nutrition
Both are heterotrophic, but fungi secrete enzymes and absorb dissolved nutrients, while bacteria show a wider range of metabolisms including autotrophy.
Medical treatment
Antibiotics that hit peptidoglycan or 70 S ribosomes work on bacteria but not on fungi. Antifungals target ergosterol synthesis (azoles), bind ergosterol (amphotericin B) or block β‑glucan synthesis (echinocandins).
Bottom line
Bacteria are simpler prokaryotes, fungi are more complex eukaryotes with a very different cell wall and membrane chemistry. That is why the drugs and diagnostic tests we use for each group are so different.