More than you ever wanted to know about yeast

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More than you ever wanted to know about yeast

Post by LG11 » Mon Dec 01, 2014 6:11 am

Hi
I am new here and mentioned a few things in the welcome center, this post in a continuation of that. So if you want a little background on how this post appeared the thread that started it is here http://homedistiller.org/forum/viewtopi ... 27&t=52488.
By request I have been asked to keep this at a level that most people can grasp, I will do my best but equally if anybody wants more in depth information I will supply links etc to papers that should give you all the information you want.
First a quick introduction for those that dont read the 'Hi I am new here threads'
I am a scientist that works in Biotechnology, my professional and personal research at the moment is based around yeast. I dont drink however and my interest in my personal research revolves around getting yeast to make other things besides Ethanol, currently most of my effort is based around getting them to produce Isoamyl Alcohol.
I cant do it all in a single post so I will just keep adding to this thread. Two things first though, some information I use might come from current research I am being paid to do, therefore I will be unable to use anything I have yet to publish in the public domain, where possible I will supply an alternative reference though.
The other thing is I also have a fully equipped laboratory at home as well as work, so if anyone wants certain experiments doing etc shout up and we will get it done. I have access to a well equipped Electronics,Chemistry and biotechnology Labs so most things should be possible. I also have a Gas Chromatograph and mass spectrometer both at home and work so analyzing results will be done using more than the dip finger and taste test :D. While we do have the ability to DNA test strains this is expensive both time and reagent wise so it isnt something i will do doing routinely, but I do hope that if I get sent some interesting samples then I will do a DNA profile.

So what are yeast? what do they do? how do they do it? and where do they come from? Lets start from there.

Yeast are single celled organisms they belong to a order known as eukaryote, this just means its has cells with bits in called organelles (yes over simplified at this point), Most people view yeast as just a kind of bag that takes things in and turns stuff out, the inner workings are way more complex, as we go on we will delve deep inside the yeast cell so we can fully understand how and why it makes you a drink. The following picture is of a typical Eukaryotic cell, dont fret over all the bits yet as and when needed we can refer back to it.
cells organs.png
The pictures for now will be from the web, but as we progress and I go through things like plating wild yeast I will use my own pictures.
So what do yeast do? Well there sole aim is to live and reproduce, if you answered make booze your wrong, not all yeast make alcohol and even those that can dont always, in fact it couldnt care less what comes out of it, in that respect its no different from you and I. we pay more attention to what we ingest and trying to reproduce than we ever do worrying about whats coming out of us. Its important you wipe from your minds the notion that yeast actually want to make you alcohol, they dont care what they make, and what they make depends on what the take in, now at this point it would be easy to say what they eat, or consume. But there are different ways that yeast ingest products.
We say products because in reality not everything yeast ingest is of use to it and some are very much not healthy for them. At this point I am going to say that when I use the term yeast I am talking specifically about Saccharomyces cerevisiae more commonly known as bakers yeast................Yes sorry to disappoint some but the most common yeast you all use (including most Turbo yeasts) is Saccharomyces cerevisiae and this is plain old simple bakers yeast, yes there are different strains and later when we get into genetics I will explain some of this, but on the whole when you hear or read people talking about wine yeasts or beer yeasts, or maybe trying out bakers yeast, they are in fact all exactly the same organism.



Ok so your back from taking a stiff drink at this shocking news, better get the bottle ready again..............Yeast are not the only organism thats involved in making your drink :O..........Knowing that last statement will lead to trouble for some I will at this point offer some proof. The following is a rough flow chart of the most common organisms you will find in the majority of brewing situation, not all ferment, but as we will see later all cells (except two types of human cell) Respire, all respiration produces a by product, so like it or not each and every one of these organisms if present will be 'respiring' (in science terms) or taking a shit (in other terms) in your brew.
Some of the by products you might notice in taste or smell others you may well not notice at all, but all of then will have some effect.
The reason all affect what you produce is simple.........some organisms will be producing products that some of the others are using to make there products, This is the true art form of brewing, the ability to balance the process to obtain results that you find pleasant.
organisims.png
The reference (or proof if you like) was taken from the following paper but there are many others that cite the same


Bokulich NA, Bamforth CW. The Microbiology of Malting and Brewing. Microbiology and Molecular Biology Reviews : MMBR 2013;77(2):157-172. doi:10.1128/MMBR.00060-12.
If anyone wants a copy of the paper the PID is PMCID: PMC3668669

That will do for part1, I will stop at this point in case anyone wants deeper explanation or clarification, I will then continue later

PART 2


So before we go down the deep dark rabbit hole of detail lets take a look at where these beasts occur in the natural world, its probably a good idea to narrow this down a little and look specifically at two areas in particular, Vine yards and orchards. Although much of the following will equally apply to your gardens and hedgerows and the fruits found therein.
I do not have citations as yet that I can use for this section, I will come back and cite papers you can access for free once I have found them, I appologise for this. I had wrongly assumed that seeing as much research had been conducted in this field there would be freely available information, in turns out all the references I have used for this section come from sources such as journals that you need to pay for, or from work that is not for public publication! There will be many sources however I can cite and post links to papers you can down load freely, I just need to come back after digging them up.

So there we are at home with a freshly prepared plate of agar agar with all the correct nutrients in and perfectly sterile, we open the lid and place the petri dish down on a surface for an hour. Then proudly we place the lid on the petri dish TAPE around the outside and place UPSIDE DOWN [ You do ALL place your petri dishes tapped and UPSIDE down dont you?] in our environmental chamber (or incubator,or warm cupboard, or anywhere else that will give us the temperature we require).

If you an old hand in microbio labs jump this bit
With yeast and when using petri dishes it is GOOD and normal practice to place the plate UPSIDE DOWN in the chamber, if its a wild plate (a plate that you have allowed to self inoculate, then it is ESSENTIAL you tape around the edge and seal it. please note a single strip all the way around will suffice, there will be those that scoff at this, however none will be able to show you a paper or book that advocates any other way. So why upside down? Normally you will be plateing up in order to isolate a single colony or colonies of yeast or other organisms, unless you use very high end chambers etc its highly likely you get condensation form on your plate, it dosnt always . But to be on the safe side we store most plates upside down so any condensation formed dosnt run into colonies on the plate and spread them into others, it also helps keep the colonies fresher. So why when air plating do you seal the agar plate? Actualy on a personal level when dealing with any culture or organism I have not directly handled and know beyond reasonable doubt to be pure, I seal ALL plates. Although considered a little over the top when dealing with say culture to culture plating, I have been unfortunate enough to witness what can happen with bad practice So the reason we seal all air plates?
air plate.jpg
air plate.jpg (8.37 KiB) Viewed 5026 times
As you can see the plate contains all kinds of microbes, so what obviously they were in the air anyway so cant possibly hurt me on a plate? WRONG and very dangerous and flawed logic. When you grow a air plate you may get the odd pathogenic microbe land on the plate, if you had breathed in that SINGLE microbe your body would have taken care of it no problem, you breath in nasty pathogens all the time and never notice. However there is something called the infection level threshold, it is basically the number of an organisms you would need to be exposed to in order for infection to occur. This is important to remember, for many pathogens this may be in the region of around 100,000 organisms per ml or cubic meter of air. So your single bug would cause you no harm, however you have now stuck your single organism on a enriched plate and given it the very best of care in order to make it grow!!!! So now on your plate instead of the single pathogenic cell you have MANY MANY BILLIONS of that pathogen growing. For those that dont know this, if you take away one thing from this thread let it be the following...................... One of the biggest fallacies in microbiology is that ASEPTIC technique is designed to protect and preserve the organism your trying to grow. Good aseptic technique is actually designed to protect YOU. Remember a single pathogenic cell may do no harm, incubate it into BILLIONS open the dish and start breathing in millions of cells............... So golden rule is make sure particularly with molds that you are aware what the bad guys look like, in particular go google pics of aspergillus, some can cause some pretty nasty infections of the lungs.
NO yeast plate is worth risk, if you see anything that dosnt look right, or anything you cant identify, then safely destroy the plate and leave the seal intact (we will go through how to kill plates without a autoclave later).

Not everybody dies that messes with unknown microbes, but please take the time to learn a few things so you dont become one of the few that do die.

NEXT section I will go into the main route for yeast to get onto fruit etc, and no air is not it! sorry to have to leave it here but work calls.
............................................................................................................................................................................................

So where do our little friends live when there isnt fruit around? Where do they go and keep warm in the winter?

I have asked this at several talks I have to give at brewing conventions etc, it never ceases to amaze me how many people in the industry will tell you BEES. When I get home tonight I wil attach 2 papers that show you will not find yeast under normal circumstances in Beehives, in fact Bees hate yeast! Its bad news for a bive hive full of sugar to yeast show up. Talk to a beekeeper about propolis and they moan how it takes them ages to clean off a hive that hasnt been opened in a while. They moan about how the bees put it all around the gaps and especially around the brood chamber.
Then you ask them what do Bees make propolis for anyway? Some will instantly answer its just there kind of glue, I have had its a draught excluder (nearly close), and some simply shrug and tell you its the bees way of keeping you out. Propolis is wonderful stuff, in the laboratory I have spent hours taking this stuff apart chemically. Truly amazing properties, it also cost the bees a great deal of energy to produce, more so even than wax. So in a wild situation say in a hollow tree, you will find it all around the outside of the main cone, its also used to connect the cone along its side. This stuff is a anti microbial power house! very sticky at first then it begins to harden as more microbes are ingested on it. Yeast if you ever manage to find any in a Bee hive are always on the propolis being chemically digested.
So anyway No yeast dosnt live in beehives, no one truly knows how bees dont manage to pick up the spores from fruit etc but some how it just dosnt stick to them, all other modes are covered by the bee super glue, so how do we know bees dont get yeast on them? Because if thy did then you would find it in there gut, the main method it would be taken off from them is by grooming, this leads to organisms that get attached to bees are often found in there gut.
Apart from keeping and dissecting many bees myself (varroa research) I have searched the literature thoroughly and can find no reference to yeast in a bees gut. I will attach a paper that details how propolis deals with yeast, also as a side note bee keepers sto moaning about it when you tell them what it does.
So we know where its not so where is it? Wasp or more precisely social wasps are where they stay during the winter (the majority, there are other minor sources), this leads to a remarkable evolutionary..........................................TBC
Last edited by LG11 on Wed Dec 03, 2014 2:23 am, edited 2 times in total.

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Re: More than you ever wanted to know about yeast

Post by HDNB » Mon Dec 01, 2014 8:50 am

Subb'd for more. :ebiggrin:

you are going to have a lot of fans. thanks for the effort!
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Re: More than you ever wanted to know about yeast

Post by MichiganCornhusker » Mon Dec 01, 2014 8:55 am

Welcome, and thanks for the info! :thumbup:
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Re: More than you ever wanted to know about yeast

Post by Jimbo » Mon Dec 01, 2014 9:34 am

Yes all the yeasts we use for booze making are Saccharomyces cerevisiae. But if youre suggesting they're all the same and all bakers yeast, I suggest you roll up yur sleeves, buy a few different strains and start making some ferments. The different strains produce vastly different results, levels of congeners (esters and such), have differnet levels of floculation and attenuation (read up), different alc tolerance, different temp preferences, some work better on maltose, others on fructose/glucose etc etc etc etc. But yes, they are all Saccharomyces cerevisiae, so?
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Re: More than you ever wanted to know about yeast

Post by firewater69 » Mon Dec 01, 2014 10:27 am

Interesting post LG11, & Well put Jimbo.
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Re: More than you ever wanted to know about yeast

Post by Ferment_It » Mon Dec 01, 2014 11:07 am

GC and MS at home? You're shittin us... and genus species level cut offs are arbitrary. just because there 18S is x% similiar doesnt mean the bugs are the same. Calling all yeast the same is likely to ruffle a few feathers around here.

Also as a scientist you should be ashamed to say yeast "take a shit in your brew". You should be well aware that they are excreting the ethanol for the same reason we exhale CO2. Just something to put electrons on.


Anyways welcome from another microbiologist. That Bamforth review is a great tho. I keep a printout on my brew journal.

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Re: More than you ever wanted to know about yeast

Post by LG11 » Mon Dec 01, 2014 11:42 am

Jimbo wrote:Yes all the yeasts we use for booze making are Saccharomyces cerevisiae. But if youre suggesting they're all the same and all bakers yeast, I suggest you roll up yur sleeves, buy a few different strains and start making some ferments. The different strains produce vastly different results, levels of congeners (esters and such), have differnet levels of floculation and attenuation (read up), different alc tolerance, different temp preferences, some work better on maltose, others on fructose/glucose etc etc etc etc. But yes, they are all Saccharomyces cerevisiae, so?
I was waiting for some to jump in lol, Gents this is part one, I was asked to dumb it down a little in the introduction threads when I mentioned a few things, instead I decided to write an article purely based on scientific fact, step by step. We are some way off getting to the part of how the same organism can and does behave in different ways to different situations. My intention is too take things through to how the different genetic variations and nutrients balances lead the organism down one of its 21 different respiration pathways. So relax I am not suggesting there are not different strains or indeed even that a organism used in one batch cannot be made to behave differently in another! As for fermenting...............I work with almost ALL the Scottish distilleries and the company I work for is responsible for a great many of the strains of yeast you enjoy and use. I dont make home brew that is true, however on average I ferment and study over 20,000 400ml batches a year.
But I have limited time each day in which to post, so I am afraid there will often be times in this thread that things are left hanging. Especially at this early stage, I feel its important to take beginners through slowly from the start, once they have a good in depth overview I will start down the path of genes and different nutrient sources and how they affect the way the organism behaves and what changes to the by products of its respiration are. I also intend to show people how to correctly start and keep a yeast bank, immobilize yeast strains and the benefits of doing so.
I will probably just keep editing and adding to the first post, or things will become fragmented. Dont get me wrong I am not here just to pass on some knowledge as stated in my welcome post I am here because I am looking for strains of yeast and microbes from batches that didnt go so well.
one small point though, by the end of this post I will show you how to isolate a wild strain and use it to make both a good wine and a good loaf of bread with exactly the same strain, But I admit to not wanting to try that with commercial strains :D.

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Re: More than you ever wanted to know about yeast

Post by LG11 » Mon Dec 01, 2014 11:46 am

Ferment_It wrote:GC and MS at home? You're shittin us... and genus species level cut offs are arbitrary. just because there 18S is x% similiar doesnt mean the bugs are the same. Calling all yeast the same is likely to ruffle a few feathers around here.

Also as a scientist you should be ashamed to say yeast "take a shit in your brew". You should be well aware that they are excreting the ethanol for the same reason we exhale CO2. Just something to put electrons on.


Anyways welcome from another microbiologist. That Bamforth review is a great tho. I keep a printout on my brew journal.
I posted a link to the first thread I did, it was the one that lead to this post, go read that and you will see why I said taking a shit. As for the GC/MS yes at home along with a great deal of other equipment. Once this gets going you will get a full tour of my home lab and hopefully if people send me samples I will willing analyze them for you.

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Re: More than you ever wanted to know about yeast

Post by Jimbo » Mon Dec 01, 2014 11:59 am

Sounds good LG, I look forward to reading your follow on posts. Thanks for taking the time to share your knowledge.
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Re: More than you ever wanted to know about yeast

Post by LG11 » Mon Dec 01, 2014 12:07 pm

Jimbo wrote:Sounds good LG, I look forward to reading your follow on posts. Thanks for taking the time to share your knowledge.
Your more than welcome, I might also end up with a sample of yeast with the missing gene I am after :D. The big problem with forums and long posts is they are a work in progress for a while. The hard part is picking the stop point for the day. To be honest its kind of fun putting a long article together.

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Re: More than you ever wanted to know about yeast

Post by Ferment_It » Mon Dec 01, 2014 3:39 pm

I didnt see anything your other thread... I am missing something here? Anyways not a big deal, just bein nitpicky- lookin forward to see where this thread takes us and love to hear more about your home lab setup.

Also, you said above that you "will probably just keep editing and adding to the first post". I'm not certain but I think if you just edit your previous posts we wont get notified of new activity, so you may want to post on the thread to give it a bump.

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Re: More than you ever wanted to know about yeast

Post by buflowing » Mon Dec 01, 2014 4:25 pm

Well, LG11, this should be an interesting ride. Looking forward to it.

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Re: More than you ever wanted to know about yeast

Post by warp1 » Mon Dec 01, 2014 4:54 pm

Haven't been this excited about a thread in quite a while.....a topic I frequently google and then get lost on :) Welcome...and teach away.

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Re: More than you ever wanted to know about yeast

Post by bellybuster » Mon Dec 01, 2014 5:31 pm

Subbed, great start. Have a drink boys and let the man talk.
Very interested in your talk of yeast banks, having done so for several years. Would love to hear your take on the value of selecting positive cells from agar plates from a visual standpoint. (Sans microscope)

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Re: More than you ever wanted to know about yeast

Post by LWTCS » Mon Dec 01, 2014 6:02 pm

Welcome welcome.
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Re: More than you ever wanted to know about yeast

Post by HDNB » Mon Dec 01, 2014 6:59 pm

LG11 wrote: The hard part is picking the stop point for the day. To be honest its kind of fun putting a long article together.
you should try writing a novel with 7 other authors and no game plan. that's fun.

I just wanted to say thanks again for putting this together at a remedial level for those of us in high school here. (intellectually speaking)
I'd like to know more about yeasts but need to be brought up to speed on the whole process. Most of the yeast discussions are very dry and way the "F" over my head. Your writing style is easily understood and fun, but as you see there are some smart mo'fo's here that are educated in your subject too. may lead to some heated debate...
I doubt you will be able able to keep this at my level and keep the sharks at bay, so i guess it's up to me to get with the programme and get it figured out.
anyway, we are lucky to have you. a yeast scientist working with all the distilleries in Scotland??? are you kidding me?

you are welcome to enjoy the novel (it used to be a novella, but there is a lot of characters here) http://homedistiller.org/forum/viewtopi ... =7&t=51635
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Re: More than you ever wanted to know about yeast

Post by rad14701 » Mon Dec 01, 2014 8:18 pm

Just write what you know... No need to dumb anything down... And post your links so those of us inclined can read ahead of what you may eventually post... Several of us here have played with yeast and I'm sure any new information would be appreciated...

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Re: More than you ever wanted to know about yeast

Post by Jimbo » Mon Dec 01, 2014 8:35 pm

rad14701 wrote:Just write what you know... No need to dumb anything down...
Thank you.
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Re: More than you ever wanted to know about yeast

Post by LG11 » Wed Dec 03, 2014 2:30 am

Added a few bits, will continue later, I am having trouble attaching papers at the moment, they are just PDF files, but the audit trail software we use on our work laptops sometimes prevents us from posting in non cleared forums etc. I might try and switch over to my home pc later, and grab the files over the network.
Sorry about this It hadnt occurred to me that the server might block me from posting public files!! Nothing I post is not already in the public Domain OR was written by myself or is my own property by the way.
If the first post gets a bit over loaded with attachments etc I will split it and post some further on in this thread, but so far I have just been adding to the top

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Re: More than you ever wanted to know about yeast

Post by firewater69 » Wed Dec 03, 2014 5:15 am

I appreciate your efforts here LG. Keep up the good work.
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Continuation

Post by LG11 » Wed Dec 03, 2014 3:08 pm

I cant edit the first post! so will continue here (sorry about that).

Where was I?? Ah yes wasps, now there is some interesting literature on this but I have kind of battled posting it, on the one hand there is some interesting stuff in it, on the other there is a new paper to be published in NATURE this march. The new paper has been written by myself and two other members of our team, ethics dictate I cant release information that is in pre publication, it has passed review and will be published next year in March.
I will post the old paper as it does contain some good information, however as soon as I am able I will share the new one, this throws some new light on the subject and disproves some previously held beliefs. As always if anyone reads the paper and finds it a slog just give me a shout, I really dont mind explaining what is essentially often very dry material written by people who would describe a pen as a dye application device often used in conjunction with a cellulose material derived from biological material often from the genus populous.
wasps and yeast.pdf
(903.52 KiB) Downloaded 149 times
We are going to start to look at how it all happens, to give you an idea of how many different pathways and variables are involved inside this little organism here is a simplified diagram of some of the pathways we will look into, if anyone want we can go through then and see what effect they have, note that many strains are bred to have some of these pathways or more correctly the gene loci for the transcription of the pathway taken out.
yeast pathways pic.jpg
added in the pic from above for those that want to see what the golgi apparatus is etc
Attachments
cells organs.png

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Re: More than you ever wanted to know about yeast

Post by BoomTown » Wed Dec 03, 2014 3:43 pm

Wow! my kinda guy! love this stuff...Bring it on, please
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Re: More than you ever wanted to know about yeast

Post by woodshed » Wed Dec 03, 2014 9:01 pm

Very nice. Keep it coming.

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Re: More than you ever wanted to know about yeast

Post by Tap » Thu Dec 04, 2014 12:23 am

Subbed.

Love it.
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Re: More than you ever wanted to know about yeast

Post by Ferment_It » Thu Dec 04, 2014 7:35 am

Nature?! Congrats! Looking forward to that read.

For those of us here not in science careers, know that one or two publications in Nature is all you need to get tenure, a couple of grants, and a nice cushy chair in your office.

Sooo.. Now that I'm done gushing, any chance your hiring post docs?

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Re: More than you ever wanted to know about yeast

Post by LG11 » Thu Dec 04, 2014 9:33 am

Ferment_It wrote:Nature?! Congrats! Looking forward to that read.

For those of us here not in science careers, know that one or two publications in Nature is all you need to get tenure, a couple of grants, and a nice cushy chair in your office.

Sooo.. Now that I'm done gushing, any chance your hiring post docs?
Where do you live? We always make room for talent :D. Thanks for the kind words.
This will be my 16th paper in Nature and brings my publishing total to over 500, I will mention to my boss I am long overdue a new chair!! as mine is falling apart :D

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Re: More than you ever wanted to know about yeast

Post by LG11 » Thu Dec 04, 2014 10:01 am

Now we start to hit some rocky bits, as the diagram above shows there are many many many ways that yeast can respire, some depends on its environment like temperature etc, some on its genetic makeup and some on the nutrient/nutrients available. Because of this I can guarantee there will be facts stated that go against what some of you may have witnessed with your own eyes, so I am going to spend some time gong into detail and of course posting publications and references for you to read further.
For example some of you may well have seen the following many time.
Lets take wine just as an example, you mash up a large batch but decide to split it into two or more smaller sized vessels, its the exactly the same condition and the yeast has been added from the same jug (or whatever) at the same time, despite there being zero variables (as far as you see/can know), the wine/wines all turn out slightly different. Once we delve into the different details of the fermentation process as seen from the yeast side of things, you will understand how the is a greater chance of variability than there is of it being exactly the same.
In the Scotch whiskey industry single malts are well known, people assume this means that the whiskey in the bottle comes from a single barrel, this is not true (with this one caveat..... you do get single barrel malt whiskeys, and you PAY for them!!!). What happens is a batch (barrels laid at the same time from the same batch) are blended under the head distiller, this is done because each barrel will have a slightly different but distinct taste, its his job to make a blend of these barrels so the final product is the same as normal. dont get me wrong by same as normal I mean taste the same to 99% of people, I can assure you that there is always a variation.
Those that love single malt Scotch whiskey may be surprised to know how much variation, most will never notice and to be fair that is don to the human skill of the head distiller, but start using Gas Chromatographs and mass spectrometers etc and they tell you a different story. Within a batch of say 2000 bottles of 15 year old malt the bottles will be all the same as they are blended from the barrels, but each barrel can have upto 17% variation in chemical make up, even after its bottled, take two bottles from the same batch and you will have a variation of chemical composition no greater than <0.78%.
This is why most of what will now follow will try and explain some of the inner workings of our yeast. Its also worth noting than although man has used yeast for at least 8000 years, we still discover something new about it and how it does what it does EVERY year.
I am not sure which bit is next! I might start with the cell wall. If I dont post for a little bit dont worry, it just takes time to make sure I can find scientific literature that I can use free of charge etc on a public forum, there is little point me posting something that if you or anyone else wants to check up on has to pay £25 for the paper, so sometimes it takes a while to find a free source with same relevant information to that I have actually used.
I will also start to post in other sections about other things, such as how to do cultures,breed yeast,make a strain genetically stable,aseptic technique etc etc. Before anyone capable of boiling a egg will be able to do most of what I post.
LG

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MitchyBourbon
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Re: More than you ever wanted to know about yeast

Post by MitchyBourbon » Thu Dec 04, 2014 10:13 am

Jimbo wrote:
rad14701 wrote:Just write what you know... No need to dumb anything down...
Thank you.
Yes, thanks rad.

And thank you LG11. I will definitely read everything you are willing to share.
I'm goin the distance...

Galeoturpis
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Posts: 86
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Re: More than you ever wanted to know about yeast

Post by Galeoturpis » Thu Dec 04, 2014 8:21 pm

Welcome aboard LG11. Your posts are fascinating. I recently looked up the genes that the yeast can use to make lipids. I noted that they have no capacity to make omega 3 or 6 fatty acids yet these are a vital component to yeast cell walls. They must pick them up from the environment. Should we be adding them to our ferments? Also what about trehalose- it helps stabilize yeast cell walls and can be up to 15% of the carbohydrate content of dried yeast. It is an additive to turbo yeast. I am considering doing a high gravity ferment experiment nd want to make sure that everything is optimal.
Cheers

Ferment_It
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Posts: 92
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Re: More than you ever wanted to know about yeast

Post by Ferment_It » Fri Dec 05, 2014 7:59 am

A couple Qs galeo:

How do you figure these polyunsaturated fatty acids are "vital"?

What means are you using to claim your yeast are auxotrophic for the "capacity to make them"? Homology? If you have a fully annotated and verified genome I'm sure you wouldn't mind sharing with the rest if the world...

As the old saying goes "absence of evidence is not evidence of absence"

Trehalose is a disaccharide of glucose monomers. Last I checked there is plenty of glucose - or glucose precursors- in your wash.

_____
Edited to add:
To keep this thread clean, I started a new thread where we can discuss related topics and the research articles posted by LG.
viewtopic.php?f=39&t=52627

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