Bacterium getting resistant on one type of sanitizer?

I"ve read that bacteria can became tolerant if we are using same sanitizer continuously.

What I am wondering is:

- is this entirely true or there are some special circumstances (type of sanitizer, concentration..)?
- how long to use one sort of sanitizer and when to switch to another?
- is there sanitizer that can last longer than other?

Maybe someone can give scientific view on this topic.. or have own experiences.

I am using local sanitize solution for while and it is based on chloride (so far o problems). Now I'm not sure whether to continue to use it or replace it with something like Star San (which is based on phosphoric acid).

Does anyone here changing sanitizer to prevent bacteria become resistant?

There was a podcast years ago discussing this, and I had posted it a couple of times, but I can't seem to find it. It was either an old basic brewing or the australian podcast "craft brewer radio" (which all trace of it has been pulled down.) I tried searching a couple different keywords, but it's not leading me to what I posted. But they called them "house bugs" and did indeed say that some things can become tolerant of our sanitizers, and that it was a good idea on occasion to through them a curve ball, and switch up....if you predominately use starsan, switch to iodophor for a couple batches....every now and then alternate.

I found an old post of mine that had the links....There was a mention in the podcast on basic brewing with the guy from New Glarus, if I recall it was just a side comment about something. But unfortunately the in depth one WAS craftbrewer radio...and like I said they're gone.

But here's the post with the links.

The sanitizing products that brewers use are very good at doing their job, when used correctly. The issue with developing resistance is based mostly on human error. When suboptimal concentration (<300ppm for starsan) or pH (>~2) is of the product used, it is not as effective at sanitizing our equipment and can leave some cells behind, which could be slightly tougher (so to speak). This process repeatedly selects for contaminating bacteria/fungus that are more resistant naturally.

Like Revvy said, it certainly wouldn't hurt anything to switch sanitizers occasionally. Although when used correctly, one sanitizer would be fine for a very long time.

And you mean a chlorine based santizer, not chloride right? Never mix acids and chlorine.

I am not a microbiologist, and I don't know in which specific ways iodine and phosphoric acid kill the bacteria. But generally members of a population, if they have any amount of genetic diversity to them, exhibit varying levels of sensitivity to a toxic substance - some die much sooner than others. If any members survive the sanitation (which, by definition, they do), "natural selection" (in which you and your sanitizer play the part of nature) will cause subsequent generations to be increasingly resistant to that sanitizer. Throwing a second sanitizer at them from time to time will essentially keep those superbugs well behaved, because the odds of being resistant to both types of sanitizers are very low.

Two caveats: First of all, the sanitizers may be so toxic that all bacteria that are exposed to them for a sufficient amount of time die, no matter what. The fact that some of them survive the sanitation is then a fact of simply not having been exposed (e.g. surviving in scratches in the fermentor), rather than surviving exposure. If that is true, than it's not natural selection at work, but simply random chance. Resistance would not, or only very slowly, develop as a result.

Second, many (most?) microorganisms reproduce asexually, which makes them essentially clones of each other, with the odd mutation thrown in. If there is little genetic diversity in your bacteria, then natural selection doesn't have anything to act on.

I am (partially) a microbiologist, and the answer is "it depends", but in most situations resistance is unlikely. Sanitizers which offer easy routes to resistance rarely make it to market...

Some sanitizing agents, if used properly, work through mechanisms that cannot be evolved around. Chlorine & iodine/iodophore being examples of this - these sanitizers work by being so chemically reactive that they damage pretty much all organic materials. You cannot evolve around that - so long as there is enough sanitizer present, and it is left in contact long enough, any "buffering" capacity evolved by the bugs will be overcome.

pH (starsan) is a slightly different beast. It is exceedingly unlikely that a conventional beer-spoilage organism would evolve around these substances, which kill by denaturing (destroying) the proteins that support the organisms survival. However, if made up incorrectly (ie. not acidic enough), these sanitizers could drive evolution towards more acid-tolerant strains. It would take a hell of a lot of exposures to improperly prepared starsan to produce a strain resistant to properly prepared starsan, but it is theoretically possible. Used properly, starsan should not give bacteria an opportunity to evolve sufficient acid resistance.

Sulfate-based sanitizers have a modest risk leading to resistance. These products work primarily by messing up the movement of electrons inside of cells (which is needed for all sorts of things, including making energy). You can evolve resistance to this - indeed, there are a number of moulds and yeasts that handle it just fine - so if mis-used, there is a chance of developing resistance. That said, sulfates work best in highly acidic foods (more acidic than beer), so you shouldn't be using these anyways.

Organic sanitizers. Over the years a number of organic (as in carbon-based, not as in that stupid food movement) sanitizing agents have been developed. I'm not aware of any being used for brewing, but they are commonly found in anti-bacterial products & hand soaps (i.e. triclosan). If used improperly, these sanitizers can readily drive the evolution of resistance. Indeed, the widespread (mis)use of triclosan and other organic sanitizers, has lead to a large number of resistant organisms. But again - misuse (i.e. exposing bacteria to too little for too short a time) is needed for resistance to form.

Long story short, don't use sulfates or organic sanitizers in beer, and make up & use your sanitizers properly. Do that, and there should be no need to switch sanitizing agents.

Bryan

Revvy said:

But here's the post with the links.

Click to expand...

I'll try to search for that podcast.
As I understand, problem stated in your post was mainly because of poor or insufficient sanitation of autosiphon, so I assume if everything was done properly solution would kill the bastards.

ColoHox said:

And you mean a chlorine based santizer, not chloride right? Never mix acids and chlorine.

Click to expand...

Typo, it is chlorine..

ArcaneXor said:

If any members survive the sanitation (which, by definition, they do), "natural selection" (in which you and your sanitizer play the part of nature) will cause subsequent generations to be increasingly resistant to that sanitizer.

Click to expand...

That is how I though about it, and the reason for eventual switching sanitizers from time to time.

Warthaug said:

I am (partially) a microbiologist, and the answer is "it depends", but in most situations resistance is unlikely. Sanitizers which offer easy routes to resistance rarely make it to market... Long story short, don't use sulfates or organic sanitizers in beer, and make up & use your sanitizers properly. Do that, and there should be no need to switch sanitizing agents.
Bryan

Click to expand...

Thanks for detailed explanation.
So far I had no problems with chlorine based sanitizer I'm using, but I would rather safe than sorry.

So all in all, we can be save as long we are using sanitizer properly in right concentration (off-course, with proper cleaning before disinfection)?
I still have to find and listen to Revvy's podcast.

Yes, so long as you are using them correctly, at the right concentration, you'll be fine - especially if using bleach! If something is surviving bleach, that means you've got a thick biofilm growing somewhere, at which point that piece of equipment should be considered garbage.

Bryan

Bleach should be a 'last resort' in the brewery. Unless all traces are removed from the brewing equipment, it has a possibility of incorporating chlorophenols into your beers. There are too many other sanitizing options to consider using bleach in the brewery.

With my professional clients in the dairy and brewing industries, peracetic acid (PAA) is very popular. It has incredible killing power and persistance. I've never used it in my homebrewery. But, I'd consider it. I've been infection free with Iodophor and StarSan. I do ocassionally alternate the sanitizer to help keep any otherwise resistant bug get wiped out, although I agree with Bryan that at the concentrations we sanitize with...there is very little opportunity for an organism to become resistant. Resistance is developed when a chemical or substance is present in the environment at very low levels. We don't typically have that.

Peroxyacetic acid is a very popular brewery and dairy sanitizer as already mentioned. The biggest reason there isn't peroxyacetic offered to the homebrew market is because it can cause acid burns on your hands when not diluted. I've gotten many burn spots since starting at my brewery job. I even use gloves but if you don't know whether it's water on your gloves or acid from the bucket pump sometimes you get bit. I've started dipping my gloved/bare hands in a bucket of diluted sanitizer after pumping sanitizer to help eliminate sanitizer burns. A little caustic or isopropyl alcohol neutralizes the acid fast enough once your skin turns white, but the tingling is what lets you know you got yourself.. Anyhow I use starsan at home because it's a safer product to keep around my house compared to an industrial sanitizer that can cause burns. Peroxyacetic is attractive because it is a non-foaming sanitizer and I do hate the foaming of starsan. I know the foaming doesn't leave enough behind to affect anything but I'd still like to be able to pour it out of the damn carboy or keg.

The resistance issue has already been explained but yeah it really depends on the method of sanitizing.

I think there is a bit of confusion here regarding the term "resistance". On any given surface there is a diverse community of microorganisms, which all differe in their suceptibility to a given sanitizer. With repeated use of the same sanitizer, the issue is not that the bacteria will become resistant (extremely unlikely on a homebrewer level), but that a certain bacteria or wild yeast which is already resistant will now thrive on the surface without any competition. This is not natural selection, but rather a chemical selection mechanism.

The sanitizers used in brewing are extremely effective against the organisms were are concerned with, and the ones resistant to the sanitizers are not going to be an issue in the beer due to pH, alcohol, or oxygen content.

We're getting off topic, but...

theredben said:

I think there is a bit of confusion here regarding the term "resistance". On any given surface there is a diverse community of microorganisms, which all differe in their suceptibility to a given sanitizer.

Click to expand...

Depends on the sanitizer; no organism on earth will be resistant to a 10% bleach solution or 12ppm iodine. The various carbohydrates, lipids, and nucleic acids life is made up of are simply far too reactive with these substances for resistance of any meaningful sort to be possible.

Now sanitizers based on pH, organic sanitizers, etc, are another story.

theredben said:

With repeated use of the same sanitizer, the issue is not that the bacteria will become resistant (extremely unlikely on a homebrewer level), but that a certain bacteria or wild yeast which is already resistant will now thrive on the surface without any competition. This is not natural selection, but rather a chemical selection mechanism.

Click to expand...

You are partially correct - used correctly it is unlikely that exposed organisms will evolve resistance, and if resistant organisms are present*, they can then flourish. However, used incorrectly (i.e. too low a concentration, or too sort an exposure), and resistance can arise in beer-spoilers from repeated exposures. Resistance will increase over successive exposures, as mutation & gene transfer enrich the frequency and potency of resistance genes in the population.

That said, it is natural selection if you consider humans part of nature...selection is selection, with the same end-effect, regardless of its source.

*'if they are present' is a key point here. Most of the microorganisms you will find on the average home surface will not be of the sort resistant to things like low pH or sulfates.

Bryan

I love the science, it is my career. Although we have concluded, as mentioned by many posters, that these sanitizers are effective WHEN USED CORRECTLY. Beyond that, the mechanisms of developing resistance, the selection over time of resistant organisms involved in spoilage, and conditions provided by various sanitizing solutions, is not a relevant concern of the homebrewer.

I actually am a microbiologist, and I agree with Warthaug, Bryan and ColoHox that if used properly, we don't need to worry about resistance developing. The main concern is making sure there are no scratches or biofilm/scum that the bacteria are hiding in. Bacteria in a biofilm can be 100 times harder to kill. So if I got an infection I'd swap equipment or processes before I considered swapping the disinfectant, assuming you're using something 100% effective like starsan or iodine.