China scientists discover giant viruses in the deepest place on Earth
- Extreme conditions at the depths of the Mariana Trench in the Western Pacific Ocean support the little-known mimivirus, researchers say
- Some mimiviruses are large enough to be seen with the naked eye but are not believed to be harmful to humans
The many legends of giant sea creatures have been largely debunked because of the challenges to large, complex life forms at the greatest ocean depths.
But the researchers discovered several giant viral species, including mimiviruses – which typically use amoeba as their hosts – in sediments taken from a seabed nearly 11,000 metres (36,000 feet) below sea level at Challenger Deep.
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Chinese manned deep-sea submersible gets rare look at deepest ocean depths, the Mariana Trench
And, while giant viruses have been found elsewhere, they appeared to be more abundant at the extreme depth, where pressure is 1,100 times that of the atmosphere, than in other conditions, where they are usually rare.
Previous attempts to obtain viral samples from Challenger Deepfailed because of the extreme technical challenges but samples collected five years ago by the advanced research ship Zhang Jian yielded enough material for the team to obtain genome sequences of 15 different types of viruses and more than 100 kinds of other microorganisms.
The researchers also raised more than 2,000 strains of microorganisms in a high pressure laboratory environment, although they were unable to revive any of the viruses, according to a paper published this month in the journal Genome Biology.
“The full biosphere structure and functional exploration of microbial communities of the Challenger Deep of the Mariana Trench, the deepest known hadal zone on Earth, lag far behind that of other marine realms,” wrote Li Xuan, a professor with the Institute of Plant Physiology and Ecology at the Chinese Academy of Sciences.