Morton table salt contains a small amount of calcium silicate as an anti-caking agent. Will this interfere when making nutrient broth to grow
bacteria?
And if it does, are there any convenient ways to purify the salt? Wikipedia and the CDC say calcium silicate has a solubility in water of 0.01% at
20C. I'm thinking of dissolving table salt in distilled water, chilling the water, filtering the solution to trap some of the silicate, spinning the
filtrate in a centrifuge to sediment any remaining silicate and then decanting the solution and maybe recrystallizing it.
Will this work? Is there an easier way?
Also, is there a special name for what remains on the filter when something is filtered?
MrHomeScientist - 12-2-2019 at 14:22
Seems unnecessary, but then again I don't know anything about bacteria. The amount of other chemicals in table salt is miniscule. If you want to be
sure, you can follow the procedure you suggested. Personally, dissolving and filtering off insolubles at room temperature, and then crystallizing the
salt is plenty pure for me.
A quick googling suggests that "filtride" covers the solids and filtrate is the liquids, although I've never heard anyone use the term filtride
before.
[Edited on 2-12-2019 by MrHomeScientist]morganbw - 12-2-2019 at 16:03
Perhaps if it could be used as an antibiotic if that is determined to be the case.
Big industry involved trying to determine how to destroy bacteria.j_sum1 - 12-2-2019 at 16:05
Also, is there a special name for what remains on the filter when something is filtered?
IME, most people use the terms "filter cake" or "residue".
Filtride is actually a pretty good name. I might start using it.CharlieA - 12-2-2019 at 18:05
For the solid remaining on the filter, I have seen the terms filtrand, and (a nod to j_sum 1) filter cake or residue. I have never seen the term
filtride before, but one can always learn something new.Tsjerk - 13-2-2019 at 08:03
Bacteria will be fine with table salt, no need to purify. A bit of calcium will be there anyway and I don't see how silicate would intefer.
What species are you growing?
[Edited on 13-2-2019 by Tsjerk]Carbon8 - 13-2-2019 at 11:18
Thanks to all for their comments.
I'm preparing to grow E. coli strain BL21, which contains a plasmid that codes for luminescence proteins. Here's a link:
Are you using ampicillin? It helps to keep the coli maintain the plasmid. Not necessary persé, but if you can I would do it. Most important though is
that it keeps contaminations out if you are re-streaking your strain.
Coli can definitely handle a bit of anti-caking agent. Carbon8 - 15-2-2019 at 14:15
Tsjerk, thanks for the tip. I didn't buy ampicillin, but I have some amoxicillin from a old prescription that I'll try instead.ModernCaveman - 29-2-2020 at 17:45
e. coli is usually grown in Luria broth which contains (depending on recipe) various amounts of salt. I've used plain table salt, celtic sea salt,
etc. and it has never been a problem.
Texium - 29-2-2020 at 19:42
I use Canning and Pickling Salt for chemistry, because it doesn’t contain any anti-caking agents or other additives and it comes in a large box for
very cheap. Just good ol’ NaCl.unionised - 1-3-2020 at 01:32
If the traces of calcium silicate in salt killed e coli then it wouldn't be in all our guts.
