Yeah, that was a glaring error by the author of the article... However, upon re-reading, I noticed this sentence a few paragraphs above:<p><i>&gt; &quot;The bacteria get all of their carbon from just one source, be it methane or carbon dioxide,&quot;</i><p>So I&#x27;m guessing the author really wanted to say &quot;the bacteria&#x27;s ability to <i>fix carbon from</i> methane and carbon dioxide is of particular interest&quot;.<p>I&#x27;m guessing that the full cycle is the same as the above-ground cycle of photosynthesis (CO2 + H2O + energy =&gt; O2 + food) and respiration (O2 + food =&gt; CO2 + H2O), except replacing <i>photo</i>synthesis by <i>chemo</i>synthesis.