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TWiM 63 Letters

Hugh writes:

Hi Vincent,

I really enjoyed hearing about Carl Woese in TWiM #50. You mentioned the controversy surrounding of Woese's 1977 discovery of Archea as a third domain of life, as it contradicted entrenched scientific beliefs. Although Archea soon found its way into general scientific thinking, his work brings up another fundamental idea that is still controversial today. It relates to the word 'prokaryote.' Norm Pace, one of Woese's former students, is a strong believer that we need to stop using this word. I think he makes extremely compelling arguments about the harm this word does to basic biological understanding, and thought this could be an interesting discussion point on TWiM. Here are the the titles of two papers by Norm Pace that discuss this issue. They're both geared towards a general audience: Problems with "procaryote" (Journal of Bacteriology, 2009); Time for a Change (Nature, 2006).

I recently discovered TWiM and TWiV and am now an avid listener, mostly while cooking dinner and washing dishes, which always seems like deja vu after a long day of experiments and washing glasswear at the lab. Thank you for making that process infinitely more enjoyable. Writing from Seattle, WA,

Hugh

[we had a brief discussion of this on an early TWiM; Elio if I recall does not mind the term]

Megan writes:

Hi TWIM team,

Could you do a TWIM about the archea and viruses that infect them? It is a fascinating area that doesn't get as much attention as bacteria.


Thanks,

Megan

Jim writes:

Just another update on the hand-washing issue. This link discusses the article, which costs $10 to see at the journal.

Regards,

Jim
Smithfield, VA


Mark writes:

Hello Vincent, Michael, Elio --

I enjoy TWiM, and have listened since episode #1. Keep up the good work and keep going. Out of TWiV, TWiP, and TWiM, I discuss episodes of TWiM with my wife the most!

I am writing, belatedly, to correct some inaccuracies in episode 49 "Grape-like Clusters". These are:

1. Someone, VR?, commented that French wines were the best. This is not FACT, but a matter of taste. The Latin expression "De gustibus non est disputandum" applies.

2. Michael speculated that natural yeast was used to ferment wine. This is a common belief and is mostly wrong. There is a vigorous industry dedicated to selling commercial yeasts to winemakers. A small number of boutique wineries are experimenting with using natural yeast -- these are a minority, and the quality of their results is highly variable.

I am an amateur wine maker of 17 years. See the attached image of a macro bin containing 0.5 ton of Cabernet Franc grapes from 2012. Note the white, powder-like color on the grapes -- this is natural yeast that grows in the vineyard. Note also the stems with missing grapes -- as harvest occurs the growers typically take weekly samples to measure sugar content.

In wine making, after the crush (in which a machine separate the stems from the grape berries, and in which the berries are lightly crushed) potassium metabisulfite is added to the must (the residual grapes & juice) to kill natural yeasts and inhibit fermentation. Typically 24 hours later the must is inoculated with a yeast starter and nutrients. The image of nubile virgins stamping barefoot on grapes to make wine is, sadly, a myth.


Our winemaking group purchases yeast from a company which supplies commercial wineries, Gusmer Enterprises. Attached is their 2012 catalog. Its front and back covers commemorate scientists whose discoveries were key to wine making -- Pasteur, Leeuwenhoek, Riley, or Dewar.


There are subterranean links to virology. Vincent can speak to physicist-turned-virologist Max Delbruck and his seminal work. Did you know that his uncle, also named Max -- http://en.wikipedia.org/wiki/Max_Delbrück_(chemist) -- developed a yeast, Torulaspora delbrueckii, that will live in high alcohol levels? These yeasts are especially important in California because our climate products grapes with very high sugar levels which, through fermentation, produces high alcohol levels.

3. The paper that Michael presented provided a quantitative framework to characterize and measure the differences between grapes grown in different blocks on the research vineyard. As winemakers we see a qualitative difference in each barrel of wine. Rule of thumb: half a ton of grapes = 1 barrel = 24-25 cases of wine. It is too labor intensive to produce and label at such levels, thus wine from each barrel is blended which averages out the different tastes of each barrel.


I have TWO recommendations for listener-picks-of-the-week:

-- to learn about how a Californian coup d'etat established their wines as equals to French wine makers, watch the movie "Bottle Shock" which combines fact and Hollywood sensuality; watch the trailer here: http://www.youtube.com/watch?v=DYs0kblXToA

-- to read more about the entire process of making wines from growing grapes, figuring out when to harvest them, and fermentation I recommend the book "From Vines to Wines" http://www.amazon.com/From-Vines-Wines-Complete-Growing/dp/1580171052


In closing,

in vino veritas

Mark

PS - feel free to use the grape image. The catalog image is technically copyrighted, though I doubt Gusmer would care if you want post it.

grapes: https://docs.google.com/file/d/0B8dwAT4VdQdjRHlIdlFjdVJndVU/edit?usp=sharing

catalog: https://docs.google.com/file/d/0B8dwAT4VdQdjN3RUMHZqcjFjSmM/edit?usp=sharing

 

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