we make our TBS/T stock like this:
50 ml 2M Tris pH7.6
70 g NaCl
8 ml Tween 20
dH2O up to 1 L
Now, twice already our stock wash got full of hairy mould. The first time the contamination was in the stock Tris as well, in some other buffers so I autoclaved all the bottles used for the next time.
But yesterday again, moulds. No other solution was afected this time. I don't think the stock Wash was opened more than a few times and expect normal circumstances.
I don't know what to do to prevent this, we don't do WB so often, so the stock may stay there for month or so. It is not very efficient get contamination again and again and remake it everytime before doing WB.
I wonder what can be improved. I'm not sure at all about the quality of our distilled water, but in other stocks it doesn't make such problems. I can have autoclaved dH2O. But what other options, can I autoclave TBS/T? Or just TBS and then add Tween later?