Sweet success

 作者:巢引     |      日期:2019-03-07 02:09:00
By Anil Ananthaswamy, San Francisco Algae that normally need sunlight to survive have been genetically modified to grow in the dark. The algae feed on glucose and could be grown inside industrial fermenters, say US researchers. This would provide a cheaper and more efficient way of cultivating algae on a large scale for use in aquaculture feed, for producing health supplements such as beta-carotene, or for development and discovery of pharmaceutical compounds. Traditionally, biotechnology companies cultivate photosynthetic algae in large outdoor ponds. But microbes can contaminate the ponds and variations in temperature and light can make controlled growth of algae difficult. Algae that use glucose instead of sunlight for energy could grow in controlled environments inside massive stainless steel vats, says Kirk Apt of Martek Biosciences Corporation of Columbia, Maryland. “This work is outstanding and provides a novel approach in the area of algal biotechnology,” says Michael Borowitzka of Murdoch University in Perth, Australia. But Borowitzka cautions that the species used in the experiment is not used in the industry and that industrial applications are some way off. Also people may not easily accept nutritional supplements produced from genetically modified algae, he says. Martek Biosciences currently uses algae to make fatty acids that are used in infant formula. But these are already made from algae that naturally grow in the dark. The company will not use genetically modified algae to produce such supplements, says Apt. “Our intention for the modified ones is pharmaceutical applications,” he says. The algae were persuaded to change their habits by the insertion of a glucose transporter gene into the microalga Phaeodactylum tricornutum. The gene, found in human red blood cells, produces a protein that helps cells absorb glucose. “The protein ends up in the outer membrane of the cell and then moves glucose into the cell,” says Apt. When exposed to sunlight, the genetically modified algae grew well as much as the wild-type strain. But in complete darkness and in the presence of glucose, the GM strain grew fives times more than it did in the presence of light, while the wild-type algae did not grow at all. More at:Science (vol 292,