Georgia Tech researchers found many types of bacteria, include E.coli, in the middle to upper regions of the troposphere. (Photo: USDA)

Scientists have discovered a considerable number of living microorganisms, including bacteria, in the middle to upper regions of the troposphere, the region of our atmosphere that’s about seven to 20 kilometers above the Earth’s surface.

Researchers from the Georgia Institute of Technology said their findings might help other scientists learn more about the role microorganisms play in forming ice that may impact weather and climate.

Health and medical experts studying the transmission of disease could also benefit by gaining new insight into long-distance transport of bacteria.

Conditions in the troposphere cannot support most other forms of life without the aid of special equipment. Temperatures there can drop to as low as -55° C and the air pressure and density are considerably lower than on earth.

Microorganisms, such as bacteria, are plentiful and can be found everywhere on the Earth and in the sea.

These hardy little forms of life not only survive but actually thrive in some of the harshest conditions known to man. They live within other forms of life, such as the human body; in the soil and the air surrounding us; in scalding hot springs; the great depths of the ocean; and inside rocks deep within the Earth’s crust.

A view outside the window of a DC-8 aircraft as air samples are gathered for a NASA study. Georgia Tech scientists found living microorganisms in the samples. (Photo: NASA)

The microorganisms  documented by Georgia Tech scientists were gathered from air samples recovered as part of NASA’s 2010 Genesis and Rapid Intensification Processes (GRIP) program, which studies low- and high-altitude air masses associated with tropical storms.

NASA gathered the air samples from aboard a DC-8 aircraft that flew over both land and ocean, including the Caribbean Sea and portions of the Atlantic Ocean during and after two major tropical hurricanes in 2010, Earl and Karl.

Attaching a special filter system developed by the Georgia Tech team to the aircraft’s outside air sampling probes, researchers were able to collect numerous particles, including the microorganisms.

Once the air samples were taken, the filters were removed from the aircraft and sent to researchers for examination.

Rather than resorting to conventional cell-culture techniques to make their analysis, the researchers instead used genomic techniques, including polymerase chain reaction (PCR) – a biochemical technology used in molecular biology that magnifies a piece of DNA, allowing scientists to generate millions of copies of the DNA sequence, as well as gene sequencing to spot and estimate the quantities of microorganisms contained within the air samples.

The researchers found more bacteria than fungi among the microorganisms.

“We did not expect to find so many microorganisms in the troposphere, which is considered a difficult environment for life,” said one of the study’s authors, Kostas Konstantinidis, an assistant professor at Georgia Tech. “There seems to be quite a diversity of species, but not all bacteria make it into the upper troposphere.”

Terry Lathem, a graduate student in Georgia Tech’s School of Earth and Atmospheric Sciences, aboard a NASA DC-8 aircraft while gathering samples of microorganisms in the atmosphere. (NASA)

The living bacterial cells found made up about 20 percent of the total particles detected within the size range of 0.25 to 1 microns in diameter.

Air samples taken over the ocean were found to contain mostly marine bacteria, while primarily terrestrial bacteria was found in samples taken above land.

The researchers also found that hurricanes had a major impact on the distribution and dynamics of microorganism populations.

Kostas Konstantinidis joins us for this weekend’s radio edition of Science World.  He’ll tell us how these findings could help advance research in climatology and medicine.

Check out the right column for scheduled air-times or listen now to the interview below.

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(Photo: Nicolas Holzheu via Flickr/Creative Commons)

People can tell how old you are by how you smell, according to new research published in the journal PLoS One.

It appears that “old person smell” some people complain about is for real, that elderly people emit a unique identifying odor.

An elderly individual’s “old person smell”  is actually acknowledged and accepted in cultures throughout the world.  In Japan, there’s a special word, kareishū,  that describes it.

Funny thing though, according to the research, all age groups rated “old person smell” as less intense and less unpleasant than the body odors of middle-aged and young individuals.

Our sense of smell, coupled with our unique body odor, provides us with a very powerful and effective method of non-verbal communication.

The body odors of other, non-human animals, hold a wide assortment of a number of chemical components that can communicate a wide variety of social information.  Scientists say that the intensities of the chemical behind those odors and how they are perceived by others tend to change throughout a person’s life.

“Similar to other animals, humans can extract signals from body odors that allow us to identify biological age, avoid sick individuals, pick a suitable partner and distinguish kin from non-kin,” said Johan Lundström, senior report author, who is a sensory neuroscientist at the Monell Chemical Senses Center in Philadelphia, Penn.

Scientists have theories regarding how these age-related odors relate to mating and how they help animals choose their suitable mates.  For example, certain scents might suggest that older males are more desirable because they contribute genes that allow offspring to live longer, while older females might be avoided because their reproductive systems are more fragile.

In conducting the research for the study, scientists collected samples of body odor from people in three age groups. Those between 20 and 30 years old were considered to be the young group, those 45 to 55 were the middle-age group and the old age group was made up with people between 75 and 95 years-old, with 12 to 16 people per group.

Each test subject slept in an unscented t-shirt that contained underarm pads for five nights.  These pads where then cut into four pieces and placed into separate glass jars.

A group of 41 young (20 to 30 years old) people served as evaluators and were each given two of the test jars in nine combinations and were asked to identify which of the samples came from older people and evaluate the odors based on  intensity and how pleasant each one was.   These young evaluators were then asked to give an estimate as to the age of the donor of each sample.

The evaluators were able to differentiate people in each of the three donor age groups based strictly on odor.  Odors from the old-age group drove the evaluator’s ability to discern age.  The researcher also said that they found that the young evaluators rated the old-age body odors as being less intense and not as unpleasant as the odors from the young and middle-age groups.

“Elderly people have a discernible underarm odor that younger people consider to be fairly neutral and not very unpleasant,” said Lundström. “This was surprising given the popular conception of old age odor as disagreeable. However, it is possible that other sources of body odors, such as skin or breath, may have different qualities.”

In future studies, the researchers will try to identify the primary biomarkers that evaluators use to identify age-related odors and to determine how the brain is able to identify and measure this information.