|WikiProject Microbiology||(Rated Start-class, Mid-importance)|
Cyclic electron transport, etc
I highly doubt it's the SAME electron that recombines with P840, etc. The hole will likely be filled almost immediately before that electron completes the chain (primary donor should be S or Fe). In fact, it's likely a chain reaction of electron transfers at the appropriate energy levels. Perhaps the simple explanation is more understandable though.
As to the restriction to cyclic electron flow - I believe the terminal electron acceptor is CO2 (after Cytochromes, Quinones and NADPH) so where's the cycle? Perhaps I'm incorrect or missing the point here as well. AFAIK, FAPs can grow photomixotrophically, so they should be able to fix carbon. GSBs definitely should be able to fix carbon - there's no supplied carbon source aside from calcium carbonate (which is just dissolved CO2) in the media.
I don't know if there's an intrinsic restriction on PSII not being able to split water in the absence of PSI. My impression was the little buggers would never want to invest in the extra C-terminal domain protein if it ended up producing a toxin for their growth - most of these guys shy away from oxygen. Additionally, isn't producing oxygen a "waste of energy?" (I'd have to look again at my energy diagrams for delta G/E) There'd be no selective advantage (besides killing your neighbors with oxygen toxicity) to re-inventing the water-splitting wheel. Obviously if they split water into oxygen, they would, by definition no longer be anoxygenic phototrophs.
Retinalophototrophy not a word
This article has a passage that Wikilinks to "Bacterial rhodopsins" piped to "rhodopsin-based retinalophototrophy." The problem is that there is nothing in the "Bacterial rhodopsins" article that discusses "retinalophototrophy." Furthermore, the word "retinalophototrophy" gets no hits on Google Scholar. On Google Search it gets hits, but mainly to the entire sentence found here, suggesting those hits are just quoting this article. The exception is some dissertations, which don't carry a lot of weight. I would like to recommend using more widely recognized terminology. Zyxwv99 (talk) 22:17, 4 October 2015 (UTC)
Retinalophototrophy was a term used by D. Bryant (and/or D. Ward) in lectures and seminars circa 2010 - especially to distinguish it from chlorophototrophy. My apologies for using a word not entered into the peer-reviewed literature. Pagelm (talk) 19:55, 5 October 2016 (UTC)