Science Briefs: 'Superbugs' breeding in sewage plants

December 22, 2013 

‘Superbugs’ breeding in sewage plants

Tests at two waste water treatment plants in northern China revealed antibiotic-resistant bacteria were not only escaping purification but also breeding and spreading their dangerous cargo.

An international team of scientists found “superbugs” carrying New Delhi Metallo-beta-lactamase (NDM-1), a multidrug-resistant gene first identified in India in 2010, in waste water disinfected by chlorination. They found significant levels of NDM-1 in the effluent released to the environment and even higher levels in dewatered sludge applied to soils.

The study, led by Rice University environmental engineer Pedro Alvarez, appeared this month in the American Chemical Society journal Environmental Science and Technology Letters.

“It’s scary,” Alvarez said. “There’s no antibiotic that can kill them. ... We often think about sewage treatment plants as a way to protect us, to get rid of all of these disease-causing constituents in waste water. But it turns out these microbes are growing. They’re eating sewage, so they proliferate. In one waste water treatment plant, we had four to five of these superbugs coming out for every one that came in.” news.rice.edu

Advances made with modified-gene poplars

Forest geneticists at Oregon State University have created genetically modified poplar trees that grow faster, have resistance to insect pests and are able to retain expression of the inserted genes for at least 14 years, a report in the Canadian Journal of Forest Research has announced.

The trees are one of the best successes to date in the genetic modification of forest trees. The advance could prove especially useful in the paper and pulp industries, and in an emerging biofuel industry that could be based on hybrid poplar plantations.

With this genetic modification, the trees were able to produce an insecticidal protein that helped protect against insect attack. A number of the GMO trees in this study also had significantly improved growth characteristics, the researchers found. Compared to the controls, the transgenic trees grew an average of 13 percent larger after two growing seasons in the field, and in the best case, 23 percent larger. oregonstate.edu

Domesticated cats traced to ancient China

Five thousand years before it was immortalized in a British nursery rhyme, the cat that caught the rat that ate the malt was doing just fine living alongside farmers in the ancient Chinese village of Quanhucun, a study in the Proceedings of the National Academy of Sciences has confirmed.

“At least three different lines of scientific inquiry allow us to tell a story about cat domestication that is reminiscent of the old ‘house that Jack built’ nursery rhyme,” said study co-author Fiona Marshall, an archaeologist at Washington University in St. Louis.

“Our data suggest that cats were attracted to ancient farming villages by small animals, such as rodents that were living on the grain that the farmers grew, ate and stored.”

The study provides the first direct evidence for the processes of cat domestication.

“Results of this study show that the village of Quanhucun was a source of food for the cats 5,300 years ago, and the relationship between humans and cats was commensal, or advantageous for the cats,” Marshall said. “Even if these cats were not yet domesticated, our evidence confirms that they lived in close proximity to farmers, and that the relationship had mutual benefits.” wustl.edu

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