Showing posts with label Fungi. Show all posts
Showing posts with label Fungi. Show all posts

Monday, August 20, 2018

Wines by modern Prometheus?

I recently read an article entitled 'Frankenstein wine' warning over French supergrapes.

Apparently, French wine scientists have developed some vines that are impervious to fungal attack, specifically downy mildew and powdery mildew, and therefore requiring little or no fungicidal chemicals.  You'd think that this was a good thing and would be welcomed.  But no, some people, who may have a vested interest in turning back innovation, are claiming that the "lab-grown creations" combine genes from around the world and could lead to dumbed-down, low-grade "Frankenstein wine", whatever the hell that means.  The implication is that the new varieties are somehow unnatural.  As far as I can tell, genetic engineering has not been involved; conventional cross breeding has been used.

Let's just step back from this hysterical attack on scientific improvement in winemaking.  As a result of claimed cancer links among grape growers, the French are under intense pressure to reduce the amount of fungicides used.  The use of these new varieties would therefore seem to be a good move.  However, a winemaker and researcher from western France has claimed that these vines, which are  hybrids, would lead to "artificial and unnatural 'Frankenstein wine'."  According to the article, he likened the development of the new vines to crossing a monkey with a man - technically feasible but going against nature. That is a completely over-the-top reaction, but I'd be keen to see the resulting animal!

The development and growing of hybrid grape varieties has in fact been going on since the 1950s in the northeast and Pacific Northwest of North America.  Those varieties have enabled production of wines in these short season, cooler and more humid areas.  They also have greater resistance to disease and therefore require less use of chemicals.

Though rare, natural interspecific hybrids do occur as a result of cross-pollination, the earliest known was discovered in 1740 near a vineyard planted in Vitis vinifera.

Wednesday, December 24, 2014

Fungi for Christmas!

The image below is my Christmas card to you all.  I didn't create it - the image has been doing the rounds on a science website, but it is truly a microbiologist's Christmas card.




For those who are interested, the Petri dish was seeded with the following:
Top: Talaromyces stipitatus; Tree: Aspergillus nidulans; Ornaments: Penicillium marneffei; Trunk: Aspergillus terreus
Not all of these are likely to be found in food -  T. stipitatus was isolated from rotting wood and can produce some interesting enzymes that may have application in the agri-food industries, P. maneffei can cause human disease, mainly in HIV patients.  A. nidulans was probably one of the first fungi I studied as a microbiology undergraduate, and has been very important in the study of recombination, DNA repair and experimental evolution.

Friday, June 8, 2012

Don't be an Alice

In Lewis Caroll's Alice in Wonderland, Alice found that taking a bite out of a mushroom would make her grow very tall; the other side made her shrink.  At one level, this is a childrens' tale, or at another it could be argued to be about taking hallucinogenic drugs.

Unfortunately, if you don't know what you are doing when it comes to eating mushrooms, you can wind up taking a different kind of trip - to the hospital or the mortuary.

There are many mushrooms (fruiting bodies of fungi) that can be eaten.  At this time of year in New Zealand, the mornings are often damp and we see mushrooms and toadstools popping up all over the place.  In my opinion, field mushrooms, Agaricus campestris, have a much better, stronger flavour than cultivated mushrooms bought from the supermarket.  They are a delight to collect and eat and I have spent many hours walking around our small farm searching for these delicacies.

But how can you tell if a mushroom is safe to eat?  My grandfather told me that you should cook them in cream and eat them on toast for supper.  If you woke up in the morning, they were edible!  This is NOT the way.  Neither is peeling and cooking a way of making mushrooms safe - the toxins of many poisonous fungi, such as the Amanitas are not destroyed by heating. 

The only safe way to know if a mushroom is edible is to have a good knowledge of their appearance and where they are found.  There are guides to help you identify mushrooms and toadstools, but to the untrained eye, many different species look the same.  If you aren't sure, don't eat!

Even the terminology is open to interpretation.  Strictly, the word ‘mushroom’ refers only to the genus Agaricus.  The cultivated mushrooms sold in the supermarkets are usually the white buttons of Agaricus bisporus, though we do see other varieties, such as the large browns. The word 'toadstool' is then used to describe any other fruiting body with a cap and stem that appears different from Agaricus, often implying that it is poisonous.

I took the following from an ABC report that followed the death this week of a Chinese visitor to Australia who appears to have eaten Death Cap (Amanita phalloides) toadstools:

History:

  • Death cap mushrooms are considered the most poisonous in the world and one is enough to kill an adult human.
  • At least six people have died and at least 12 made sick from eating death cap mushrooms in Australia in the past decade.
  • Death caps have been involved in the majority of deaths around the world from mushroom poisoning, including that of Roman emperor Claudius.

Appearance:

  • Death cap mushrooms are similar in appearance to several species of edible mushrooms commonly used in cooking, such as paddy straw mushrooms and Caesar's mushroom.
  • Death caps may be white but are usually pale green to yellow in colour, with white gills and a white or pale green stalk up to 15cm long. (See image below from Wikipedia)
  • The entire mushroom is poisonous and cooking or peeling the mushroom does not remove toxicity.

Symptoms:

  • Death caps are said to taste pleasant and symptoms can occur six to 24 hours after consumption.
  • Initial symptoms can include abdominal pain, diarrhoea, vomiting, hypotension and jaundice, followed by seizures, coma, renal failure and cardiac arrest.

Habitat:

  • Death cap mushrooms can be found in parts of south eastern Australia, particularly ACT and parts of Victoria.
  • They are commonly found near established oak trees and some other hardwood trees and are most common during later summer to early winter after heavy rain or irrigation.
  • It is thought death caps were introduced to Australia with the importation of different hardwoods.

Treatment:

  • Death caps are extremely poisonous and if consumed it is a medical emergency.
  • Anyone who suspects they have eaten a death cap should seek immediate medical attention and where possible take a mushroom sample for identification.  
There are approximately eight toxins in A. phalloides, the major ones being α-amanitin and β-amanitin, which inhibit RNA polymerase.  This prevents protein synthesis, resulting in the death of cells.  The liver is usually the first organ to be damaged, often irreparably, and later the kidneys.
Picture of Amanita phalloides from Wikipedia:  http://en.wikipedia.org/wiki/Amanita_phalloides


Have a look at Peter Valda's comments on mushrooms and toadstools:

http://www.burkesbackyard.com.au/1997/archives/27/in_the_garden/gardening_tips,_books,_techniques_and_tools/mushrooms_and_toadstools