I was looking this up and I'm wondering if so far I'm correct about the following:

• For the most part eukaryotes do aerobic respiration, which involves glycolysis, the Krebs cycle and oxidative phosphorylation involving ATP synthase and an ETC
• Prokaryotes can either do aerobic respiration, anaerobic respiration or fermentation, the first two of which require an ETC and ATP synthases, which would be located in the plasma membrane of the prokaryote

If that is the case, I was wondering if there are prokaryotes that only do fermentation, and if so do they have ATP synthases and an ETC? In other words, are there any organisms without ATP synthases and an ETC (which would force them to survive on fermentation alone, unless there is some other method of energy production in prokaryotes that doesn't use ATP synthases and an ETC that I'm missing)?

Thanks