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:

The most effective diabetes drugs don't reach enough patients yet

Breast cancer risk in younger women may be influenced by hormone therapy

Strategies for staying smoke-free after rehab

Commentary questions the potential benefit of levothyroxine treatment of mild hypothyroidism during pregnancy

Study projects over 14 million preventable deaths by 2030 if USAID defunding continues

New study reveals 33% gap in transplant access for UK’s poorest children

Dysregulated epigenetic memory in early embryos offers new clues to the inheritance of polycystic ovary syndrome (PCOS)

IVF and IUI pregnancy rates remain stable across Europe, despite an increasing uptake of single embryo transfer

It takes a village: Chimpanzee babies do better when their moms have social connections

From lab to market: how renewable polymers could transform medicine

Striking increase in obesity observed among youth between 2011 and 2023

No evidence that medications trigger microscopic colitis in older adults

NYUAD researchers find link between brain growth and mental health disorders

Aging-related inflammation is not universal across human populations, new study finds

University of Oregon to create national children’s mental health center with $11 million federal grant

Rare achievement: UTA undergrad publishes research

Fact or fiction? The ADHD info dilemma

Genetic ancestry linked to risk of severe dengue

Genomes reveal the Norwegian lemming as one of the youngest mammal species

Early birds get the burn: Monash study finds early bedtimes associated with more physical activity

Groundbreaking analysis provides day-by-day insight into prehistoric plankton’s capacity for change

Southern Ocean saltier, hotter and losing ice fast as decades-long trend unexpectedly reverses

Human fishing reshaped Caribbean reef food webs, 7000-year old exposed fossilized reefs reveal

Killer whales, kind gestures: Orcas offer food to humans in the wild

Hurricane ecology research reveals critical vulnerabilities of coastal ecosystems

Montana State geologist’s Antarctic research focuses on accumulations of rare earth elements

Groundbreaking cancer therapy clinical trial with US Department of Energy’s accelerator-produced actinium-225 set to begin this summer

Tens of thousands of heart attacks and strokes could be avoided each year if cholesterol-lowering drugs were used according to guidelines

Leading cancer and metabolic disease expert Michael Karin joins Sanford Burnham Prebys

Low-intensity brain stimulation may restore neuron health in Alzheimer's disease

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