荷兰教授用干细胞制造牛肉
荷兰马斯特里赫特大学教授马克·波斯特研发出了世界上最贵的汉堡，该汉堡造价高达25万英镑(约合人民币236万元)，汉堡中使用的牛肉并非来自牧场的牛群，而是从牛的干细胞中培育出来的。
The world's first test-tube burger will be served in London next week. It is made from meat grown in a laboratory, rather than cattle raised in pastures.
And its developers hope it will show how the soaring global demand for protein can be met without the need for vast herds of cattle.
The 5oz 'Frankenburger', which cost £250,000 to produce, is made from 3,000 tiny strips of meat grown from the stem cells of a cow.
The raw meat is said to be grey with a slippery（滑的） texture similar to squid or scallop（扇贝）.
It has been created by Professor Mark Post, from the University of Maastricht in Holland.
His research has been funded by an anonymous businessman – who may be the first to try the burger.
He told The Independent on Sunday: 'Right now, we are using 70 percent of all our agricultural capacity to grow meat through livestock. You are going to need alternatives. If we don't do anything meat will become a luxury food and will become very expensive.'
A four-step technique is used to turn stem cells from animal flesh into a burger.
First, the stem cells are stripped from the cow's muscle.
Next, they are incubated（孵化，培养） in a nutrient broth（营养液体培养基） until they multiply many times over, creating a sticky tissue with the consistency of an undercooked egg.
This 'wasted muscle' is then bulked up through the laboratory equivalent of exercise - it is anchored to Velcro and stretched.
Finally, 3,000 strips of the lab-grown meat are minced, and, along with 200 pieces of lab-grown animal fat, formed into a burger.
The process is still lengthy, as well as expensive, but it could take just six weeks from stem cell to supermarket shelf.
His work is funded by the Dutch government, as well as an anonymous donation of 300,000 Euros - but it remains to be seen, however, whether the pioneering development will find favor with a public that likes to think of its chops, steaks and sausages（香肠） as having their roots in nature, rather than in test-tubes.
Scientists say that it is possible the meat will be sold to the public within ten years.
Every kilo of meat requires 10 kilos of plant feed and oil, but cultured meat would only need two.
According to the Food and Agricultural Organisation we will be eating twice as much meat as we do now by 2050.
It is thought that the new form of meat could be acceptable to vegetarians, and animal rights organizations have already given their approval.
Oxford university scientists said in 2011 that cultured beef would need 45 percent less energy than natural beef.
They added that it would require 99 percent less land than regular livestock and produce between 78 and 95 percent less greenhouse gas.
But, the difficulty may be persuading the public to eat an artificial product.
Professor Post said that it is possible to add fatty tissue and nutrients to it, changing the taste and making it more palatable for the public.
But before it became commercially viable, the Food Standards Agency have said that they would have to provide evidence showing it is safe for the public to consume and nutritionally equivalent to regular meat.