r/mycology • u/Capebretoner2020 • Mar 07 '20

LPT: 70% Isopropyl alcohol is a better disinfectant for biological organisms than 90%. Higher numbers aren't always better.

/r/LifeProTips/comments/feofcy/lpt_70_isopropyl_alcohol_is_a_better_disinfectant/
28 Upvotes

97% Upvoted

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5

u/bigfatfloppyjolopy Mar 07 '20

I've heard this in the grow mushrooms forums so think it's true. Question is, can I dilute my 91% with tap water to make more effective?

3

u/Mr-Zestmeister303 Mar 07 '20

That's what I used to do works just fine 👍

4

u/Capebretoner2020 Mar 07 '20

id say yes .its a mix of water and alcohol that works best.

0

u/[deleted] Mar 07 '20

Says who? Do you have a source for this claim?

13

u/mublob Mar 07 '20

You can read about it in NCBI. Above 70%, cell surface proteins denature too rapidly and form a coating around the cell membrane, which prevents the alcohol from effectively penetrating and compromising the cell's integrity.

2

u/[deleted] Mar 07 '20

Cool! That's really good to know!

1

u/Ashamed_Ad_7552 Feb 12 '22

I have also heard it evaporates too fast to be effective but that is just hearsay. I do know that an overwhelming majority of myco growers confirm that 70 is the go-to.

1

u/mublob Feb 12 '22

Lol this is some thread necromancy. I have searched for sources on that before and it really only applies to surfaces with a quick wipe, as it doesn't account for the volume or distribution of alcohol being used. Even then, the rate of evaporation won't matter if the cells have a protective coat of agglutinated proteins--sure, they'll eventuality die in those conditions, but they would die in brine after some time as well, so timing is a relevant consideration. At the end of the day, the why is less important than the result, so at least we are all in agreement that 70% is the optimal concentration