Blogs / 80beats

Genetically engineered bacteria can now produce long-chain alcohols that could be used as biofuel, scientists report in the Proceedings of the National Academy of Sciences [subscription required]. Remarkably, the researchers synthetically modified the bacteria’s metabolism to churn out a type of energy-rich alcohol not normally found in nature. “Previous metabolic engineering work typically produces compounds that already exist in nature,” says coauthor James Liao… “Our work here aims to produce compounds that are not synthesized in nature” [Science News].

In addition to ordinary genetic engineering, which involves taking genes from different species (in this case, genes from yeast and a cheese-making bacteria), the new study also required a third, custom-made artificial gene. The three genes were inserted into the genome of E. coli bacteria. The researchers designed the genes to extend E. coli’s metabolic pathway so that toward the end, the precursor compounds that would normally get converted into amino acids instead turn into long-chain alcohols [Technology Review]. These long-chain alcohols string together six carbon atoms, packing in more potential energy per molecule. Ethanol has only two carbon atoms, and no other naturally-occurring alcohol contains more than five.

(more…)

The germ-fighting power of bleach lies in its ability to unravel cellular proteins, according to a new study. Researchers at the University of Michigan report that the active ingredient in bleach, hypochlorous acid, irreparably alters the three-dimensional structure of proteins in living cells—to fatal effect. They also found that some bacteria possess a special protein that can somewhat counter the ravages of hypochlorous acid. The findings clear up a hitherto murky understanding of how the common household cleaner does its job. “Everyone knew that bleached worked, and that was enough,” says [researcher Ursula Jacob]. “Few really cared how it worked” [Nature News].

In fact, Jacob’s team didn’t set out to answer that question either. They were studying a bacterial protein known as heat shock protein 33 (Hsp33) that helps other proteins maintain their proper shapes. Hsp33 is activated in times of stress, such as when the bacteria is exposed to high temperatures. “At high temperatures, proteins begin to lose their three-dimensional molecular structure and start to clump together and form large, insoluble aggregates, just like when you boil an egg,” said study lead author Jeannette Winter… Like a boiled egg, those proteins can never revert to their previous state, and the stressed cells eventually die [LiveScience.com].

(more…)