MICROBIOLOGISTS PROBE LAKE LAYSAN FOR UNIQUE BACTERIA AND OTHER ORGANISMS IN SEARCH OF NEW DISCOVERIES

Today environmental microbiologists Stuart Donachie and Renee Harada collected water, sediment and substrate samples from Lake Laysan, the large hypersaline lake in the middle of Laysan Island, Northwestern Hawaiian Islands. As the description suggests, this lake has a high salt content, two and a half times that of sea water. The lake is at least 22 feet deep but has been described in previous literature as up to 30 feet deep.

Their work is part of a three-year National Science Foundation "Microbial Observatories" grant to the University of Hawaii to study the diversity of bacteria in the five 'true' lakes in the Hawaiian Islands. Lake Laysan is the only such lake in the northwestern Hawaiian islands, the other four are located in the main Hawaiian islands. These researchers consider true lakes to be those unaffected by human disturbance and non-altered by development, channelization or creation as a reservoir.

While on island, the pair collected water samples from various locations of the large lake using a variety of equipment, including a sterile, inflatable rubber raft to traverse the water. They also scooped up sediment; and gathered microbial 'mats,' the term scientists use to describe the material found on the lake bottom which are comprised of multiple layers of bacteria.

Stuart Donachie and Renee
Harada prepare to investigate
microbial life at Laysan Island

The samples are collected first for their water chemistry, to identify specific nutrients found in the water and to test the level of salinity (of salt) in the water. This information is used to indicate how the lake differs from other lakes, based on its chemical make up.

The microbiologists also use the samples they collect to cultivate bacteria from the lake, in the hopes of finding new bacteria that have never been identified or scientifically described before.

According to Donachie, "In the scientific world, we are very familiar with millions of plants, animals and insects. But of the tens of thousands of bacteria we know are out there, scientists worldwide have only been able to cultivate and describe 4,200 species so far. We know many more are out there and it's our job to discover these new bacteria."

The cultivated bacteria may hold properties like useful enzymes and antibiotics used in the pharmaceutical world or for other chemical or industrial use. The bacteria may also be useful in bio-remediation, the use of bacteria to solve environmental imbalances or mitigate the effects of environmental pollution like oil or chemical spills.

"The possibilities are endless," said Harada when describing how the cultivated bacteria can assist human kind.

According to Harada, from the samples collected, they will only be able to cultivate less than one percent of all the bacteria that exist in the sample because the nutrients provided won't be suitable growing fuel for the bacteria. To find out the other 99% of bacteria that exists in a place like Lake Laysan, the biologists also use the water and sediment samples to extract the DNA and RNA from organisms in the sample and study them.

"Every species of bacteria has its own unique DNA base sequence, or fingerprint, which help us identify the species and set it apart from others," said Harada. "By studying these samples at the molecular-biological level back at the lab, we will be able to identify which species of bacteria exist in the Lake that we already know of. Or, if it has a new base sequence we've never seen before, we can describe the organism for the first time." To do this, the pair will use a relatively simple, and proven, centrifuging system to 'spin out' the DNA and RNA.

Discovering new species is what excites Donachie and Harada more than anything else in their work. "I like the potential for discovery. That's what we do at our lab at the University of Hawaii under Dr. Maqs Alam. We discover new organisms and describe them to science. There are so many bacterial species yet to be known to science and the thrill of finding them is what makes all our work worthwhile," said Donachie.

Stuart Donachie uses a salinity
gauge to measure the water at
Laysan Island's hypersaline lake

The scientists will spend four to six months in the lab when they return identifying and describing the organisms they found. The will use the information to compare it to what they find at the other four lakes. When the comparison is complete, they will be able to identify which specific groups of organisms grow under which unique conditions and what evolutionary factors may have helped them evolve in relative isolation.

The other true lakes in Hawaii they are studying include Lake Waiau at the top of Maunakea on the Big Island; Green Lake, also on the Big Island; Kauhako Lake on Molokai; and Waieleele Lake at Haleakala on Maui.

"Each lake is so very different," said Donachie. "That's what's so interesting about studying those in Hawaii. These lakes all exist in remote locations, making them perfect places for unique, perhaps endemic, species to develop and establish in isolation. We're anxious to find out what kinds of unique bacteria exist where."

These scientists have to be committed to what they do to spend a total of thirteen days on a ship in order to get one, eight-hour chance at collecting the samples they need for their study. The pair have been patiently waiting for this opportunity since they joined the scientific team aboard the vessel Rapture on October 7th at Midway Atoll.

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