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Scientists brew cannabis using modified beer yeast

nature.com

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Re: Scientists brew cannabis using modified beer yeast

#71

Post by vanderZwan »

bullfightonmars wrote: post #69
vanderZwan wrote: post #47

Earlier quoted context omitted.

So this accidentally made me go down a speculative rabbit hole... Cannabis is apparently a C3 plant[0]. It's also not a perennial. So while you have a point, there is still room for improving efficiency. I tried looking up what the current status with genetically modifying plants with high photosynthetic efficiency was. First thing I found was... tobacco[1]. Yeah, that's not all that useful. More generally, I wonder…

Given that tobacco is also a C3 plant your link to the post about improving tobacco photosynthesis by reducing the cost of photorespiration is exactly the mechanism I expect to be exploited by any scientist/company seeking to improve C3 photosynthesis. This work is based around is tobacco because it is an excellent model crop for transformation and in situ agricultural studies. Not because this lab is explicitly seek…

I apologize for being too negative about the tobacco, you are absolutely right. The paper concludes that it is hopeful for improving grain crop yields:

> We are optimistic that similar gains may be achieved and translated into increased yield in C3 grain crops because photorespiration is common to all C3 plants and higher photosynthetic rates under elevated CO2, which suppresses photorespiration and increases harvestable yield in C3 crops.

However, does not refute the other papers I have linked about C3/C4/CAM photosynthesis that suggest that C4 may not be universally beneficial, but an optimization in certain contexts only. I do hope enhancements to plants in agroforestry settings, or restorative agricultural practices in general, are also possible. Those are badly needed if we want to regenerate topsoil and perhaps even make food production a net carbon-sink.

Re: Scientists brew cannabis using modified beer yeast

#72

Post by Obi_Juan_Kenobi »

jakobegger wrote: post #22
a_imho wrote: post #18

How does yeast modification actually work?

You take a gene from a plant, change the codons to whatever yeast uses, and then you put it into the yeast DNA. The hard part is that presumably multiple genes are required to produce a compound, and getting all of them to produce stuff at the right rate is probably difficult as well, since we don't 100% understand how to regulate gene expression.

> You take a gene from a plant, change the codons to whatever yeast uses

This isn't necessary; codon usage is very basal. The biggest challenge you might face is prokaryotic vs. eukaryotic expression, but that's due to processing of the transcript (e.g. splicing) and the nascent peptide (e.g. all kinds of stuff). Messing with codons is simply optimization.

Expression is indeed the hard part, but not because of regulation. The general strategy is to use inducible promoters: grow the yeast, add chemical, get protein/metabolite.

Because this isn't constitutive, you can get away with a lot; even high levels of expression that will kill the cell will still produce enough of the desired product that it's an effective approach. And even relative gene-product dosage isn't too bad because you can associate the different gene products with particular known promoters and enhancers, etc.

What you have to account for is the general state of the cell; is it producing enough precursors, are intermediate products toxic, do they need to be confined for modification/processing, etc. etc. Doing complicated biochemistry gets messy.

Making simple peptides, e.g. insulin, is easy, and that's why it was the first GM pharmaceutical. Making a whole biochemical processing facility in a cell is .. a bit more of a challenge.

Re: Scientists brew cannabis using modified beer yeast

#73

Post by Obi_Juan_Kenobi »

a_imho wrote: post #24
jakobegger wrote: post #22

Earlier quoted context omitted.

You take a gene from a plant, change the codons to whatever yeast uses, and then you put it into the yeast DNA. The hard part is that presumably multiple genes are required to produce a compound, and getting all of them to produce stuff at the right rate is probably difficult as well, since we don't 100% understand how to regulate gene expression.

Thanks! Could you shed some more light on how one actually takes a gene from a plant (in a lab setting I suppose) and put it into yeast?

* Extract RNA

* Reverse-transcribe this into DNA

* PCR amplify target sequence using custom primers. Generally you design the primers to create restriction sites flaking the sequence of interest.

* Restriction digest the amplicons

* Pop that into a cloning vector, e.g. Gateway

* Clone and isolate a colony

* Sanger sequence to confirm you've got what you want

* Move construct into expression vector

* Transform yeast with expression vector construct

* Sequence some colonies to find one that worked well (these vectors use resistance genes to provide an easy screening process)

* Once you've confirmed it worked, you're all set.

You can just use plasmids or do a stable transformation; the latter is harder but it's what you'd want for commercial production I think.

Re: Scientists brew cannabis using modified beer yeast

#74

Post by foxyv »

This seems like a nice end-around for the argument that weed isn't medically pure. I remember one of the arguments against medical marijuana was that CBD and THC aren't the only active chemicals that weed is producing. In this case you can create only the chemicals you want when conducting trials and manufacturing pharmaceuticals.

Re: Scientists brew cannabis using modified beer yeast

#75

Post by schwartzworld »

cma wrote: post #70
klmr wrote: post #39

Earlier quoted context omitted.

> When you use yeast, you have to supply the energy for the entire system The “entire system” is a vat with yeast in it. For starters, that’s a much more space efficient way of growing something than in plants. Secondly, the energy you provide to the system, in brewing, is just sugar, which is incredibly cheap. In fact, given that this works well, at large scale, for beer brewing (i.e. ethanol production), why do you…

> For starters, that’s a much more space efficient way of growing something than in plants. You have to account for the land use by the sugarcane (no idea how things would net out).

Sugar can come from other sources than cane. Most cheap alcohol is made from grain which has had its starches converted to sugar with enzymes. If you aren't concerned about flavor, the process is very inexpensive.

Re: Scientists brew cannabis using modified beer yeast

#76

Post by schwartzworld »

dumbfoundded wrote: post #5

As someone in this industry, I doubt this will become a reality. The real problem is cost. When you use yeast, you have to supply the energy for the entire system. When you grow a plant, you get free energy from the sun. The cost savings are hard to beat. Nicotine extracts aren't made from yeast either. That should be a big warning flag for the business sides of these cool projects.

Much cannabis is grown indoors where you also have to "provide the energy for the entire system".

Re: Scientists brew cannabis using modified beer yeast

#77

Post by dang »

klmr wrote: post #40
dang wrote: post #38

Earlier quoted context omitted.

Ok we've modified the title.

Why? The original title was totally fine.

If a user complains about a title being baity and they have a point, we tend to change the title on the grounds that many other readers probably feel the same way.

This was a borderline case but I think they had a small point that 'hacked' was a bit baity. Also, the GP comment was heavily upvoted, indicating that a lot of users agreed.

Re: Scientists brew cannabis using modified beer yeast

#78

Post by klmr »

dang wrote: post #77
klmr wrote: post #40

Earlier quoted context omitted.

Why? The original title was totally fine.

If a user complains about a title being baity and they have a point, we tend to change the title on the grounds that many other readers probably feel the same way. This was a borderline case but I think they had a small point that 'hacked' was a bit baity. Also, the GP comment was heavily upvoted, indicating that a lot of users agreed.

> and they have a point

But they don’t: the usage of “hack” in the title was squarely within the original definition of “to hack” (for instance, it’s covered by definition 6 in the Jargon File if we accept [as is generally done in hacker culture] that such hacks aren’t restricted to computer usage). In non-technical usage the term “hack” tends to mean something else but given that HN literally has “hacker” in its title, shouldn’t we accept correct usage of the word on this site, even if it doesn’t fall outside its non-technical mainstream definition?

Speaking as a biologist, the usage of “hack” in the title is completely idiomatic within the field (compare: “genome hacking”). The claim that this usage is bait is simply factually incorrect.

> Also, the GP comment was heavily upvoted

On the contrary, it was downvoted (greyed out) at the time the title was changed. It’s now back to black.

Re: Scientists brew cannabis using modified beer yeast

#79

Post by klmr »

AllegedAlec wrote: post #42
dang wrote: post #38

Earlier quoted context omitted.

Ok we've modified the title.

It wasn't meant as commentary on you using it as the title. It's more that it's a stupid pop-sci term that has no place in the communication of a giant such as Nature.

It’s not pop-sci at all. It’s a term typically used within the field for what is described here.

Re: Scientists brew cannabis using modified beer yeast

#80

Post by dang »

klmr wrote: post #78
dang wrote: post #77

Earlier quoted context omitted.

If a user complains about a title being baity and they have a point, we tend to change the title on the grounds that many other readers probably feel the same way. This was a borderline case but I think they had a small point that 'hacked' was a bit baity. Also, the GP comment was heavily upvoted, indicating that a lot of users agreed.

> and they have a point But they don’t: the usage of “hack” in the title was squarely within the original definition of “to hack” (for instance, it’s covered by definition 6 in the Jargon File if we accept [as is generally done in hacker culture] that such hacks aren’t restricted to computer usage). In non-technical usage the term “hack” tends to mean something else but given that HN literally has “hacker” in its tit…

The baitiness comes from the over-use of the word in headlines. I don't disagree with you but unfortunately accuracy is not the only concern.

Re the GP comment, I was referring to https://news.ycombinator.com/item?id=19299892, which was always upvoted and quickly reached a high positive score. When users are expressing an allergic reaction like that, we've learned that it's best to just yield. A modified title can be just as accurate and usually reduces inflammation.

That said, I think your argument is at least as persuasive. We did the standard moderation thing in this case because, as I said, it's proved to be globally optimal. But it doesn't seem to have been locally optimal here.

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