Does all photosynthesis use CO2?

[dae]

I can't find an easy answer to this online, so does all photosynthesizing life use carbon dioxide (or carbonic acid/bicarbonate/carbonate) as the source of carbon?

Thanks!

[JackBean]

That's definitelly good question We have always learned about different hydrogen donors, but never about this
As there are, besides photoautothrophs (like plants etc.), also photoheterotrophs, I would guess yes, also other compounds can be found. Try to find more about them and maybe will you find your answer

[JackBean]

OK, bad shot
http://www.oxygraphics.co.uk/anoxy.htm
"Although the amount of bacteriochlorophyll in these photoheterotrophs is lower than in other photosynthetic bacteria, they are capable of fixing CO2 during photosynthesis, and light enhances their growth."

So then, I guess yes, all of them use CO2

[MrMistery]

yeah, I think all of them use CO2, since i have never heard of photosynthesis without Rubisco.