Cai from Multus offered us a pretty good price to make up 50x 100ml bottles of trace nutrient solution. All that we needed to do was provide them with the powders.
Sourcing chemicals to produce Rabaey, Yu or SL6 or even a combination of these that minimised chlorides (to avoid Cl2 then hypochlorous acid [bleach] production at the anode) but included all critical ions wasn’t so difficult.
But I had a bee in my bonnet about getting these food grade, so that we could say that our single cell protein strains have only ever been fed with food grade nutrients. Unfortunately we haven’t managed to find suppliers of food grade:
NiCl2.6H2O: Nickel(II) Chloride Hexahydrate
CoCl2.6H2O: Cobalt(II) Chloride Hexahydrate - could we use vitamin B12?
H3BO3: Boric Acid - we found one US supplier, but they won’t ship overseas, and are making enquiries with a European supplier we have just found.
It seems very unlikely that we’ll find a food grade source for nickel. In this paper from 1970 it does appear that nickel is a required trace element for Xanthobacter autotrophicus, so we can’t just leave it out.
Something caught my eye while looking at a new amendment to EU regulations regarding maximum nickel levels in food that comes into force next year. Maybe a wild idea, but given the comparatively large amount of nickel allowed in seaweed (30-40 mg/kg), could we use seaweed as a source of trace minerals?
I was thinking that the question would be how we know if a particular seaweed has all the nutrients required. One relatively easy way would be running comparisons with full-range trace minerals and seaweed. I was thinking that the seaweed may not let the optimum culture grow, but conversely any given nutrient mix may conceivably optimise conditions for a sub-optimal strain. It could be that we have a better strain (in terms of taste, nutrition, etc.) in an enrichment culture but it is outcompeted by an inferior strain for us. Given our limited analytical capabilities we’d never know. So perhaps I’ve been overthinking it…
Perhaps the best route is to take the best ingredients (in terms of sustainability, availability, cost & consumer optics) and just see what grows with them. If it’s good, great. If nothing grows, try different ingredients. If that’s correct then the main thing is probably getting as many different cultures running as we can.
Earlier in this thread I mentioned SeaChem Flourish tabs:
I went through the whole list of Seachem products today and almost fell off my chair when comparing the ingredients of Seachem - Reef Trace to our list of trace elements:
Boron
Cobalt
Copper
Manganese
Molybdenum
Zinc
Rubidium
Nickel
Vanadium
It contains everything from Yu et al and SL-6 and is only missing iron and calcium from Rabaey et al (which may not be required). It has some rubidium that may not be necessary, but everything else is useful for HOB! I’ve ordered a 100mL bottle so that I can finally start my first HOB experiment.
Brilliant, and an excellent price, I’ve just bought a bottle myself - I see under Allergen Information on Amazon that they are Yam Free!, but more usefully, here’s the contents per 1 g:
So I’ve been trying to calculate how Reef Trace compares to Yu et al and Rabaey et al. I used ChatGPT to calculate the proportions of each element (based on the molar mass of the compounds) and their amounts per gram (to be able to compare against the information provided by Seachem):
So one element that Reef Trace could be deficient in compared to the others is cobalt, but the other elements are at least in the same ball park. That is if the calculations are correct - it may be a good idea for someone to double-check this.
Well I tried to do this with in my first chat with ChatGPT’s new Advanced Voice. I also did it in a spreadsheet and got the following when I exclude Rabaey’s iron and calcium (which we can easily get elsewhere):
Reef Trace
Rabaey (ex Fe & Ca)
Yu
SL6
Zn
53.26%
23.60%
14.92%
14.80%
Mn
26.79%
19.51%
5.46%
5.42%
B
8.82%
0.74%
34.41%
34.14%
Cu
10.08%
0.52%
1.67%
2.43%
Ni
0.01%
4.16%
3.24%
3.21%
Mo
0.95%
10.03%
7.80%
7.74%
Co
0.09%
41.43%
32.50%
32.25%
So yes, by my calculations cobalt is most lacking, but nickel is only fractionally better (the two hardest elements to source food grade, not that Reef Trace is food grade anyway). Molybdenum is also only 12% of the lowest of the three published trace minerals.
Glad to hear your results match mine. So I think we should be able to use Reef Trace as a trace mineral solution, adding 1mL per litre. It will be interesting to see if the lower levels of nickel and cobalt turn out to be rate-limiting.
Do you think we’ll then be selecting for HOB that can cope with low CoNiMo?
Definitely worth cracking on anyway to see what we get. But if the Reef Trace cultures underperform the literature, that would be the first thing to check.
