Plant microbe shares features with drug-resistant pathogen

Jun 16, 2009

An international team of scientists has discovered extensive similarities between a strain of bacteria commonly associated with plants and one increasingly linked to opportunistic infections in hospital patients. The findings suggest caution in the use of the plant-associated strain for a range of biotech applications. The genetic analysis was conducted in part at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, and will be published in the July 2009 issue of Nature Reviews Microbiology, now available online.

The research team - which included scientists from Ireland, Austria, and the United Kingdom as well as the U.S. - was investigating the versatility and adaptability of a group of bacteria known as Stenotrophomonas. These bacteria have great metabolic versatility, allowing them to thrive in very diverse environments.

The scientists were particularly interested in comparing two strains of S. maltophilia whose genomes were recently decoded to see why these strains - one isolated as an opportunistic pathogen from a clinical setting (strain K279a), and the other from the roots of poplar trees (strain R551-3) - were so well-suited to their very different environments. Such comparisons are made possible by the high throughput and cost-effective DNA sequencing capacity developed by DOE's Joint Genome Institute, as well as the Sanger Institute, to help elucidate the role of microorganisms in health, energy, and environmental processes.

"Surprisingly, we observed very few differences between the opportunistic pathogen and the common plant bacterium," said Brookhaven Lab microbiologist Daniel (Niels) van der Lelie, an expert on soil- and plant-associated microbes, whose team provided the data on the plant-dwelling strain.

For one thing, the scientists found genes that make the bacteria resistant to a wide range of antibiotics in both strains. "This suggests that antibiotic resistance is part of the species' core genome, and not a trait acquired in the hospital," van der Lelie said. Multi-drug antibiotic-resistance is one key feature that allows some bacteria to cause deadly infections in hospital patients whose immune systems are often compromised.

The scientists are also intrigued about similarities in the mechanisms the two strains use to colonize their respective environments. For example, both strains possess very similar mechanisms to produce glue-like substances, or biofilms, which allow them to adhere to plant roots, in one case, and medical devices such as ventilation tubes and intravenous catheters, in the other. Such devices are a common source of exposure to opportunistic pathogens for hospital patients.

Implications

"Soil microorganisms have long been a source and inspiration for the synthesis of antibiotics," van der Lelie said. "These finding will help us to better understand the potential of bacteria to produce or become resistant to antimicrobial compounds."

The findings may also reveal new targets for the development of drugs to interfere with microbes' ability to form sticky, infection-fostering biofilms, or point the way to closely related non-pathogenic strains that could be useful and benign for biotech applications.

On the other hand, these findings raise the question of whether plants in hospital settings may serve as a reservoir for opportunistic pathogens or antibiotic resistance genes. "This is something that should be looked at more closely by experts in infectious diseases," van der Lelie said.

The findings also suggest caution in using this particular strain of plant-dwelling bacteria for a range of biotech applications for which it and other plant-associated have shown promise. These include: stimulating plant growth and protecting plants against pathogens; the breakdown of natural and man-made pollutants via bioremediation and phytoremediation; and the production of useful biomolecules such as drugs or industrial enzymes.

Based on the results of this study, van der Lelie's group has ruled out S. maltophilia for biotech applications designed to increase plant growth. "The work in our lab is presently concentrating on two other plant-growth promoting , Pseudomonas putida W619 and Enterobacter sp. 638, neither of which contain broad spectrum or virulence factors that would allow them to behave as opportunistic pathogens," he said. "We are certain about this after carefully analyzing the genome sequences of these strains."

Source: DOE/Brookhaven National Laboratory

Explore further: Two-armed control of ATR, a master regulator of the DNA damage checkpoint

add to favorites email to friend print save as pdf

Related Stories

Scientists Identify Bacteria That Increase Plant Growth

Jan 26, 2009

(PhysOrg.com) -- Through work originally designed to remove contaminants from soil, scientists at the U.S. Department of Energy's Brookhaven National Laboratory and their Belgium colleagues at Hasselt University ...

Using microbes to fuel the US hydrogen economy

Sep 13, 2006

"If the U.S. is to have a future hydrogen-based economy, we'll need a way to generate abundant quantities of hydrogen safely and economically," said Daniel (Niels) van der Lelie, a biologist at the U.S. Department of Energy's ...

Elevated carbon dioxide changes soil microbe mix below plants

Dec 19, 2007

A detailed analysis of soil samples taken from a forest ecosystem with artificially elevated levels of atmospheric carbon dioxide (CO2) reveals distinct changes in the mix of microorganisms living in the soil below trembling ...

Resistant gut bacteria will not go away by themselves

Jun 19, 2007

E. coli bacteria that have developed resistance to antibiotics will probably still be around even if we stop using antibiotics, as these strains have the same good chance as other bacteria of continuing to colonise the gut, ...

Superbug genome sequenced

May 07, 2008

The genome of a newly-emerging superbug, commonly known as Steno, has just been sequenced. The results reveal an organism with a remarkable capacity for drug resistance. The research was carried out by scientists ...

Recommended for you

Japanese scientist resigns over stem cell scandal

Dec 19, 2014

A researcher embroiled in a fabrication scandal that has rocked Japan's scientific establishment said Friday she would resign after failing to reproduce results of what was once billed as a ground-breaking study on ...

'Hairclip' protein mechanism explained

Dec 18, 2014

Research led by the Teichmann group on the Wellcome Genome Campus has identified a fundamental mechanism for controlling protein function. Published in the journal Science, the discovery has wide-ranging implications for bi ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.