Siderophores function as mechanisms of competition between species, so the importance of their specificity so that, once linked to iron, establish a reserve of this trace element for the species that produced them. On the other hand, a species capable of taking advantage of more than a sideróforo, or capable of producing a more powerful sideróforo and able to rob iron of sideróforos weaker, also would have a competitive advantage, and it is real, it exists.
The biofilms on our teeth also produce organic acids. I guess these are more effective in dissolving the calcium Phosphate.
The cyanobacteria do it in tanks with normal day/night rhythms. It makes no sense for them to be exposed to light when nutrients are used up and so they go into the substrate to accumulate new nutrients.
Not in the test tube but in the tank: The cyanobacteria compete with corals for nitrogen and trace elements. When phosphate is low the coral growth will be slowed down or stopped. Now the cyanobacteria can make use of N and trace elements that the corals consumed previously and of phosphate that is not in the water any more but can be found in the substrates and rocks.
I'll post this in hopes someone has some ideas on what might be killing off oscillatoria here.
Here's a look at oscillatoria dying (or not) in closed spaces.
Culture wells with different amounts of cyano in each well. Sealed the tops off with plastic and left under diffused tank lighting for ~24hrs.
Low concentrations lived, high concentrations mostly died, and higher concentrations died completely.
Top pic, immediate preparation, middle after clumping, bottom pic 24hr later.
I prepared a slurry of oscillatoria from my tank and mixed them up then dropped varying amounts in each well. From left to right 1 drop cyano slurry in 10 drops total (tank water), 3 cyano / 10 total, 9 cyano/10 total etc. as labeled in bottom pic.
[The pink water is from pigment (phycoerythrin) leaking out of cells indicating death of oscillatoria, the strands are green after they've leaked the pigment out.]
The lowest concentrations (1/10, 3/10, 1/20) lived, the 9/10 had mostly dead cyano but there were some ~10% living cyano strands remaining. The 15/15 had all dead cyano and lots of dead nematodes and copepods. (notably, almost nothing kills nematodes)
30/30 was difficult to see anything.
I can't figure what caused death here. Whether the high concentrations of cyano depleted something they need pretty urgently, or the cyano produced something that needed to be diffused or processed out but couldn't.
I have no good candidates for what might've caused this.
Actually, sophisticated test unnecessary in this case. The live wells had no smell, but the dead ones burned my nose with ammonia.
It's true that ammonia from a dead culture doesn't mean that ammonia is what killed it. However it's pretty hard to find things that fit the clues here. Small concentration of oscillatoria is fine but large one self-destructs.
Some tests were a flop. Too much organics - the cultures turned to smelly death.
This on the other hand, I did as an afterthought - start with very little, innoculated with oscillatoria cells and gradually fed particulate matter.
It seems that this has sufficient conditions to grow as much cyano as one could possibly want.
BUT
Which subset of these conditions was actually necessary?
YAs you can see, 1 through 3 were not sufficient on their own. The culture weakened from days 10-13. adding #4 & 5 from day 13 forward really caused the cyano to rally.
- Sand, pre-soaked in Phosphate rich medium (F/2 at double strength for a couple of days)
- Initial media 1/10th F/2 media (5ppm NO3, 0.35ppm PO4, trace elements)
- Washed particulates from a mix of skimmer sludge and algae fish food as nutrients. Daily addition.
- CO2 supplementation: a drop of limewater on day 8, a drop of saturated baking soda water from days 13 on.
- Water changes: 50% water changes from day 13 on with initial media.
My guess is that #1 the sand was unnecessary, and #2 the media could have been totally blank saltwater - assuming that the sludge particulates were nutritious enough.
After adding fresh medium, the Spirulina growth increased but barely at all on the sand, just at the water line....
I also wonder if Oscillatoria has different PO4 requirements. That means @taricha needs to measure the PO4 level in his cultures for me
