yeast

[Ron Reefman]

In another forum (here at RC) I saw a post about using baker's yeast to remove diatoms in a reef. There was very little info from the video posted. I thought it might make for a better discussion over here.

Has anybody used yeast in a saltwater reef?
What for?
How effective was it?

Can anybody explain what the process is supposed to be? (What happens in the tank and why)

I'm not doing it and I've never heard of anybody else doing it. But then at one point somebody dose vodka to their tank and we all went... WHAT??? Now it's fairly common practice. I'm just curious to hear what others know about this process, or how it works (or doesn't work). And what are the risks.

[bertoni]

Brewer's yeast seems to have a fair amount of protein and carbohydrates in it. The protein should act as nitrate dosing, and the carbohydrates probably would act as carbon dosing. In addition, some corals or other organisms might use some of the amino acids more directly. I'd probably stick with vinegar or vodka, but if someone wants to experiment, adding small amounts should be safe.

Anything that changes the profile of mineralized nutrients in the water column can effect the population of bacteria. Many snails will eat diatoms, though, and I suspect that silicate availability can be managed so as to keep diatoms from reaching plague proportions. That said, there are other microbes that are harder to handle, and that might be what people actually are seeing.

[farfromsea]

I have absolutely no experience in this but I just wanted to chime in with a question...how would this work exactly? When I bake if I put too much salt this inhibits the yeast growth, there is a delicate balance. I've ruined plenty of breads by getting distracted when I'm measuring. I can't imagine that the amount of salt we put in would not inhibit/kill baker's yeast....

[Ron Reefman]

Thanks Jonathan.

farfromsea, I have no idea. I asked here because I saw this post in a different forum here at RC. http://www.reefcentral.com/forums/showthread.php?t=2585982

I felt it might get a better answer here in the chemistry forum. The video talks about using yeast to get rid of algae and really doesn't say how or why at all. I'm just curious.

[farfromsea]

I briefly watched the video. So they dosed bread yeast at 1/4 tsp per 400 gallons every couple of days and reportedly saw the end of the diatom bloom within 5-7 days.

I did some research into the organism (yeast)'s behavior in environments with hypersalinity and it looks like due to the stress the yeast can produce more glycerol which I would suppose is analogous to vodka (ethanol)'s role dropping phosphates and nitrates.

http://www.soeagra.com/abr/vol1/169-76.pdf

However, they also cite a study that says 3% salt (NaCl) is toxic for baker's yeast.
http://mic.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.2007/010751-0#tab2

To my knowledge salinity of 35 ppt correlates to 3.5% and if this is true I suspect the yeast would die and any potentially beneficial glycerol hyper-production would be completely eliminated.

I'm thoroughly skeptical the yeast was at all responsible.

Unless dead yeast helps export nitrates/phosphates...

[bertoni]

Well, I definitely agree that the yeast would die in short order. I actually hadn't thought that someone would try to grow yeast. I just assumed it was added as a form of food for organisms. It might serve as a form of carbon dosing, along with adding fixed nitrogen. That might allow the tank to remove more phosphate. I would stick with dosing vodka or vinegar for carbon and sodium nitrate for fixed nitrogen, but in theory, the yeast might supply some other nutrients. The advantage of the simpler additives is that we know more about what might be happening.

[Ron Reefman]

Here is a link to the thread in the Reef Discussion forum
http://www.reefcentral.com/forums/showthread.php?t=2585982
There is a video there and some posters are saying it worked for them.

I'm completely skeptical, but I'm no chemist.

[bertoni]

If it worked, which is hard to prove, I suspect it worked as does carbon dosing. If the blooms actually were diatoms, though, I suspect that they'd go away on their own, when the diatoms become limited by the availability of silicate, for example. The dosing rate that they state is very low. I'm not sure how much effect it'd have, but there are lots of possibilities as to how it might work.

[UCT]

Just commenting off the top of my head. There is a process called salt stressing where yeast are exposed to 7 percent salt concentrations before baking so its unlikely that seawater concentrations would kill off the yeast. In the presence of oxygen and carbon sources, yeast produces CO2 which raises ph. When baking, the oxygen is first consumed by the yeast in respiration process, then the yeast start anaerobic fermentation process. O2 is continuously added to the water in the reef tank, so the respiration process can continue. The reefkeeping article mentions raising ph to get rid of dinos. Perhaps this is the process?

[Anubreed]

Just commenting off the top of my head. There is a process called salt stressing where yeast are exposed to 7 percent salt concentrations before baking so its unlikely that seawater concentrations would kill off the yeast. In the presence of oxygen and carbon sources, yeast produces CO2 which raises ph. When baking, the oxygen is first consumed by the yeast in respiration process, then the yeast start anaerobic fermentation process. O2 is continuously added to the water in the reef tank, so the respiration process can continue. The reefkeeping article mentions raising ph to get rid of dinos. Perhaps this is the process?

As far as I know for the yeast to produce Co2 it needs sugars of some kind and not all sugars are ferment able especially by bakers yeast.

Maybe I will do an experiment and get out my home brew equipment and put some wine yeast in a saltwater mix and some in a salt and sugar mix and check for Co2 production.

[UCT]

As far as I know for the yeast to produce Co2 it needs sugars of some kind and not all sugars are ferment able especially by bakers yeast.

Maybe I will do an experiment and get out my home brew equipment and put some wine yeast in a saltwater mix and some in a salt and sugar mix and check for Co2 production.

Yeast produces CO2 with either aerobic respiration or anaerobic fermentation. It does not require sugar for aerobic respiration. It can use non-fermentable carbon sources. If O2 is added during the brewing process of beer, it can convert the ethanol in beer to acetic acid.

[blanden.adam]

I agree with Jon, if it works, there are many mechanisms you could hypothesize.

You might imagine a compound or impurity in baker's yeast that is magically toxic to diatoms, or that there are particular nutrients in the yeast that allow a bacteria population to out-compete the diatoms (yeast extract is one of the magic ingredients used in enriched media for bacteria growth in the lab for example). Those seem plausible to me, so who knows?

Also, I'm far from an expert in baker's yeast biology, but I do know that different strains can show drastically different tolerances to things like salt, ethanol, temperature, calcium, and any number of other things. So, I'd be surprised if the bakers yeast survived for any length of time and grew to any significant extent, but I don't think I'd rule it out 100% without testing.

[bertoni]

It's interesting that there's some evidence the yeast might survive for some time in a salt solution. I'm still a bit skeptical about it growing to any extent, but there might be some way to check or test that. Maybe it's a research topic for later on...

[Anubreed]

It's interesting that there's some evidence the yeast might survive for some time in a salt solution. I'm still a bit skeptical about it growing to any extent, but there might be some way to check or test that. Maybe it's a research topic for later on...

The thing is yeast is everywhere in the air already. So if it can live in saltwater even for a little while it would already be there.

[bertoni]

That's another good point. Microbes generally spread well on their own.

[UCT]

Wild yeast prefer a very acidic environment, which it is used for sour dough bread which is very acidic. Baker's yeast has been cultivated to work much faster than wild yeast and in a more basic environment than wild yeast can tolerate. It still prefers a more acidic condition than our reef tanks.

[farfromsea]

Yes I really can't imagine that the yeast can live at all in the tanks...

but perhaps like others stated the dead form of yeast helps in some way or another? My understanding of the chemistry of nitrate dosing is limited I need to read more.

Salt-stressing yeast is an interesting concept I haven't heard of before. I was looking into it and apparently there is a study but I can't read it because of the paywall. If anyone has some university access to this paper and wants to email it to me that would be awesome http://onlinelibrary.wiley.com/doi/10.1111/j.1750-3841.2009.01337.x/abstract Some online have stated this was a strange strain of yeast which was cultivated to survive in environments with higher salinity but of course the abstract is garbage like most papers...have to get past the paywall to find out!

I swear I would go back to school just to get access to all of the journals ;) I miss having everything at my fingertips