PAT R IK STO L L ARZ/AF P/GET T Y IM AG ES/N EWSCO M
NEWS OF THE W EEK
An explosion at this Evonik plant in Germany is affecting the global auto industry.
NYLON SHORTAGE THREATENS AUTOMAKERS SUPPLY CHAIN: A plant fire in Germany
could slow car production in Detroit
A
UTO INDUSTRY EXECUTIVES convened a spe-
cial meeting in Troy, Mich., last week to discuss how to deal with a shortage of nylon 12 stemming from a fire last month at an Evonik Industries plant in Marl, Germany. Nylon 12 is a long-chain polyamide used in automotive fuel and brake lines. On March 31, two workers were killed by an explosion and fire at the Evonik plant, which makes cyclo dodecatriene (CDT), a key intermediate for nylon 12. Evonik is still investigating the cause of the blaze and says the plant won’t be repaired for at least three months. Evonik is the only nylon 12 producer that makes its own CDT. Additionally, it is the leading supplier of CDT to other nylon 12 producers, including its chief rival, Arkema, which declared force majeure on April 6 because of the outage.
COMMON ANTIBIOTIC MECHANISM SHOWN MICROBIOLOGY: Antibiotics kill bacteria
by oxidizing guanine nucleotides
G
UANINE OXIDATION is at the heart of the cell-
killing abilities of many common antibiotics, biologists at MIT and Boston University report (Science, DOI: 10.1126/science.1219192). The findings, if confirmed, could improve scientists’ understanding of the way existing antibiotics actually work. Previously, James J. Collins and coworkers at Boston University reported that diverse antibiotics with different targets have a common cell-killing mechanism (C&EN, Sept. 10, 2007, page 8; Cell, DOI: 10.1016/j. cell.2007.06.049). They found that various antibiotics trigger the production of hydroxyl radicals, leading to oxidative damage and cell death, but they didn’t describe the process in detail. Now, Graham C. Walker of MIT and coworkers have teamed up with Collins’ group to show that a specific type of oxidative damage, guanine oxidation, is the main cause of cell death by bactericidal antibiotics. In this process, hydroxyl radicals oxidize the DNA base guanine to form 7,8-dihydro-8-oxoguanine, or 8-oxoguanine. WWW.CEN-ONLIN E .ORG
6
Paul Blanchard, a nylon analyst for the consulting firm IHS Chemical, issued a report last week saying Evonik and Arkema together account for half the world’s capacity for nylon 12, which was already in short supply before the Evonik fire. “We do not have an indication yet on how drastic the reductions in nylon 12 shipments will be, but it is likely to be serious,” he wrote. Arkema is trying to secure more CDT from other suppliers, according to Aurelien Paumier, Arkema’s North American business director for technical polymers. Two smaller CDT producers, BASF and Invista, both have pledged to pitch in. Meanwhile, Arkema has put nylon 12 customers on allocation, which in some markets can amount to a more than 50% reduction in supply. Paumier sees the crisis potentially lasting six to nine months. According to the Automotive Industry Action Group, which organized the Troy summit, delegates brainstormed ways to stretch nylon 12 inventories and capacities. They also discussed new designs and alternative materials. Paumier says Arkema colleagues at the event presented potential substitutes for nylon 12 such as nylon 10,10 and nylon 10,12. In February, Arkema purchased Hipro Polymers, a Chinese company that makes these nylons. Because nylon 12 has been in short supply for some time, Paumier adds, Arkema had already been trying to get these materials approved in automotive applications.—ALEX TULLO
Cells deal with 8-oxoguanine by excising and replacing the base in DNA, but those defenses can be overwhelmed by too much 8-oxoguanine. If the modified bases occur too often and too close together, the repair mechanism instead breaks the DNA strand. The accumulation of these breaks leads to cell death. Walker and Collins’ team treated Escherichia coli cells with different classes of antibiotics: a β-lactam (ampicillin), a quinolone (norfloxacin), and an amino glycoside (kanamycin). By adjusting the expression of enzymes in cells’ guanine oxidation defense mechanism, the researchers showed that the bacteria became less sensitive to antibiotics when expression increased and more sensitive when expression decreased. “Hydroxyl radicals are not only extremely reactive but also very nondiscriminatory in their reactions,” Walker says. “There was no particular a priori reason to suspect that oxidation of one very particular type of biomolecule was particularly responsible for cell death.” The findings suggest that the usefulness of current drugs to treat bacterial infections could be extended with adjuvants that target the guanine oxidation pathway, the researchers write. “The work is certainly interesting and thoughtprovoking,” says Shahriar Mobashery, an antibiotics expert at the University of Notre Dame. “No doubt its generality with other antibiotics, beyond the three classes that have been looked at, will be investigated in the coming weeks and months.”—CELIA ARNAUD
AP RI L 2 3, 20 1 2
