PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

UCLA life scientists, colleagues differentiate microbial good and evil

2014-01-09
(Press-News.org) Contact information: Stuart Wolpert
swolpert@support.ucla.edu
310-206-0511
University of California - Los Angeles
UCLA life scientists, colleagues differentiate microbial good and evil To safely use bacteria in agriculture to help fertilize crops, it is vital to understand the difference between harmful and healthy strains. The bacterial genus Burkholderia, for example, includes dangerous disease-causing pathogens — one species has even been listed as a potential bioterrorist agent — but also many species that are safe and important for plant development.

Can the microbial good and evil be told apart? Yes, UCLA life scientists and an international team of researchers report Jan. 8 in the online journal PLOS ONE.

"We have shown that a certain group of Burkholderia, which have just been discovered in the last 12 years as plant-growth promoting bacteria, are not pathogenic," said the study's senior author, Ann Hirsch, a professor of molecular, cell, and developmental biology in the UCLA College of Letters and Science. "This opens up the possibility of using these particular species for promoting plant growth through the process of nitrogen fixation, particularly in areas of climate change. This will have a major impact, especially on people in the developing world in producing protein-rich crops."

Nitrogen fixation is a process by which helpful bacteria that have entered the roots of plants convert nitrogen in the atmosphere into ammonia, which helps the plants thrive. The findings of Hirsch and her colleagues indicate that several recently discovered Burkholderia species, including Burkholderia tuberum, could be used — cautiously — in nitrogen fixing. These species, the scientists discovered, lack those genes that make other Burkholderia species harmful agents of infection.

"Bacteria that fix atmospheric nitrogen into ammonia, such as Burkholderia, are critical for plant growth," said Hirsch, whose laboratory studies many aspects of the complex symbiosis between plants and bacteria. "We're especially interested in these recently described Burkholderia species because they are found primarily in the dry and acidic soils of the Southern Hemisphere, making them potentially important for agriculture in less productive areas."

For their study, the UCLA life scientists performed a bioinformatics analysis of four symbiotic Burkholderia species, all of which fix nitrogen and one, B. tuberum, which "nodulates legumes." They found a strong distinction between genes in these beneficial strains and in pathogenic strains. They searched for genes typically involved in infection — for attaching to and invading cells or for secreting toxins. Unlike their dangerous cousins, the four symbiotic Burkholderia species did not have genes associated with the virulence systems found in the pathogenic species.

Burkholderia were first discovered as plant pathogens in 1949 by Walter Burkholder, who identified them as the agent causing onion-skin rot. Later, Burkholderia species were identified as the causative agent of the disease melioidosis, a public health threat, especially in tropical countries like Thailand and in parts of Australia. B. pseudomallei, which causes melioidosis, is classified by the Centers for Disease Control and Prevention as a potential bioterrorist agent.

Other Burkholderia belong to the Burkholderia cepacia complex, a group of related bacteria that are not true pathogens but can cause "opportunistic" or hospital-acquired infections in people with weakened immune systems or with cystic fibrosis. Although some members of the Burkholderia cepacia complex have been used to protect plants from dangerous fungal infections, their potential to cause infection has resulted in severe limits on their use in agriculture.

It wasn't until many decades after Burkholder's discovery that closely related Burkholderia species were found to enter plant roots not as pathogens but as helpful symbionts — generating root nodules in which the bacteria provide nitrogen fertilizer to the plant. Bacteria that cause the formation of these nodules in legumes, such as soybeans, alfalfa and peanuts, are crucial to sustainable agricultural systems, Hirsch said.

Although the nodulating, symbiotic species of Burkholderia are related to the more dangerous species, a detailed analysis of their evolutionary relationships published earlier this year by Hirsch and her colleagues showed that the two groups have a distinct evolutionary lineage.

The harmful Burkholderia species are more resistant to antibiotics than the symbiotic and agricultural strains. In addition to the bioinformatics analysis in the current study, the team analyzed resistance to a panel of common antibiotics, and tested the potential of different Burkholderia species to cause infection in laboratory conditions.

Experiments testing the potential of the four symbiotic species to cause infection in the small nematode worm known as Caenorhabditis elegans and in human cells grown in culture verified the bioinformatics analysis, showing that the bacteria were not harmful.

"We used a variety of detailed experiments to make sure that the symbiotic species are safe to put into farmers' fields and home gardens, just like currently used nitrogen-fixing bacteria," Hirsch said. "Our goal is to have these newly discovered nitrogen-fixing bacteria be used for a more sustainable approach to agriculture in the future."

### Co-authors of the PLOS ONE research included Annette Angus and Christina Agapakis, UCLA postdoctoral scholars in Hirsch's laboratory; Stephanie Fong, Paul Yang, Nannie Song and Stephanie Kano, former UCLA undergraduate researchers in Hirsch's laboratory; Shailaja Yerrapragada of the Baylor College of Medicine in Houston; Paulina Estrada–de los Santos of the department of microbiology at Mexico's Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala; Jésus Caballero-Mellado (now deceased) of the Genomic Sciences Center at the National Autonomous University of Mexico; Sergio de Faria of Brazil's Embrapa Agrobiologia; Felix Dakora of the chemistry department of Tshwane University of Technology in South Africa; and George Weinstock of the department of genetics at Washington University School of Medicine in St. Louis.

The research in Hirsch's laboratory is federally funded by the National Science Foundation, by grants from the Shanbrom Family Foundation, a UC Office of the President Presidential Postdoctoral Fellowship, and a L'Oréal USA for Women in Science Fellowship.

UCLA is California's largest university, with an enrollment of more than 40,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer 337 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Seven alumni and six faculty have been awarded the Nobel Prize.

For more news, visit the UCLA Newsroom and follow us on Twitter.


ELSE PRESS RELEASES FROM THIS DATE:

Elephant shark genome provides new insights into bone formation and adaptive immunity in humans

2014-01-09
Elephant shark genome provides new insights into bone formation and adaptive immunity in humans A*STAR-led international consortium completely decodes the first shark-family member genome 1. Singapore, Jan, 09, 2014 ...

Researchers discover how vascular disease activates autoimmune disorders

2014-01-09
Researchers discover how vascular disease activates autoimmune disorders The hardening of the arteries, also called atherosclerosis, that can lead to heart attack or stroke. has also been linked to autoimmune disorders. It has not been clear why these diseases are related, ...

JCI early table of contents for Jan. 9, 2014

2014-01-09
JCI early table of contents for Jan. 9, 2014 Engineered anti-toxin antibodies improve efficacy The effectiveness of toxin-neutralizing antibodies is considered to be mediated through the interaction of the variable region of the antibody and the toxin; ...

Engineered anti-toxin antibodies improve efficacy

2014-01-09
Engineered anti-toxin antibodies improve efficacy The effectiveness of toxin-neutralizing antibodies is considered to be mediated through the interaction of the variable region of the antibody and the toxin; however, recent studies suggest that the constant ...

Mice exposed to retinoid deficiency in utero exhibit bronchial hyperresponsiveness as adults

2014-01-09
Mice exposed to retinoid deficiency in utero exhibit bronchial hyperresponsiveness as adults Individuals with asthma and COPD are subject to debilitating bronchospasm as a result of airways that are hyperresponsive to stimuli. Factors that lead to the ...

Joslin researchers determine hormone linked to improved glucose metabolism activates browning of fat

2014-01-09
Joslin researchers determine hormone linked to improved glucose metabolism activates browning of fat BOSTON – (January 9, 2013) – Researchers at Joslin Diabetes Center have discovered that a hormone long associated with weight loss and improved glucose metabolism ...

NIH-funded scientists develop mouse model for atopic dermatitis

2014-01-09
NIH-funded scientists develop mouse model for atopic dermatitis Study identifies potential targets for eczema treatment A study reports the development of a new mouse model for atopic dermatitis, an inflammatory skin disorder ...

Rewiring stem cells

2014-01-09
Rewiring stem cells A fast and comprehensive method for determining the function of genes could greatly improve our understanding of a wide range of diseases and conditions, such as heart disease, liver disease and cancer. The method uses stem cells ...

Why is type 2 diabetes an increasing problem?

2014-01-09
Why is type 2 diabetes an increasing problem? Popular theory to explain increasing frequency of type 2 diabetes refuted by evidence Contrary to a common belief, researchers have shown that genetic regions associated with increased risk of type 2 ...

Quantum mechanics explains efficiency of photosynthesis

2014-01-09
Quantum mechanics explains efficiency of photosynthesis Light-gathering macromolecules in plant cells transfer energy by taking advantage of molecular vibrations whose physical descriptions have no equivalents in classical physics, according to the first unambiguous ...

LAST 30 PRESS RELEASES:

Exercise as an anti-ageing intervention to avoid detrimental impact of mental fatigue

UMass Amherst Nursing Professor Emerita honored as ‘Living Legend’

New guidelines aim to improve cystic fibrosis screening

Picky eaters by day, buffet by night: Butterfly, moth diets sync to plant aromas

Pennington Biomedical’s Dr. Leanne Redman honored with the E. V. McCollum Award from the American Society for Nutrition

CCNY physicists uncover electronic interactions mediated via spin waves

Researchers’ 3D-printing formula may transform future of foam

Nurture more important than nature for robotic hand

Drug-delivering aptamers target leukemia stem cells for one-two knockout punch

New study finds that over 95% of sponsored influencer posts on Twitter were not disclosed

New sea grant report helps great lakes fish farmers navigate aquaculture regulations

Strain “trick” improves perovskite solar cells’ efficiency

How GPS helps older drivers stay on the roads

Estrogen and progesterone stimulate the body to make opioids

Dancing with the cells – how acoustically levitating a diamond led to a breakthrough in biotech automation

Machine learning helps construct an evolutionary timeline of bacteria

Cellular regulator of mRNA vaccine revealed... offering new therapeutic options

Animal behavioral diversity at risk in the face of declining biodiversity

Finding their way: GPS ignites independence in older adult drivers

Antibiotic resistance among key bacterial species plateaus over time

‘Some insects are declining but what’s happening to the other 99%?’

Powerful new software platform could reshape biomedical research by making data analysis more accessible

Revealing capillaries and cells in living organs with ultrasound

American College of Physicians awards $260,000 in grants to address equity challenges in obesity care

Researchers from MARE ULisboa discover that the European catfish, an invasive species in Portugal, has a prolonged breeding season, enhancing its invasive potential

Rakesh K. Jain, PhD, FAACR, honored with the 2025 AACR Award for Lifetime Achievement in Cancer Research

Solar cells made of moon dust could power future space exploration

Deporting immigrants may further shrink the health care workforce

Border region emergency medical services in migrant emergency care

Resident physician intentions regarding unionization

[Press-News.org] UCLA life scientists, colleagues differentiate microbial good and evil