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The striking and high microbial diversity in the Monegros desert

Extreme environments hide a rich world of extremophiles microorganisms, which are able to live in conditions impossible for other beings and with a great potential of applications. CSIC scientists have studied the microbial communities in saline lakes of the Monegros Desert, in Spain, and have found a high biodiversity. Up to 35% of the genetic sequences obtained don’t match with anything known; they could be new species for science.

One of the saline lakes in the Monegros Desert. Image: CEAB/CSIC

The Monegros Desert, in Spain, has one of the most striking ecosystems in Europe. It is an extremely arid landscape, where plants and animals live in extreme conditions – up to 5.400 biological species, according to the Entomological Society from Aragon.

One of the most unknown environments in Los Monegros are the inland shallow saline lakes, locally called “saladas”. Nothing similar to these singular ecosystems can be found but in remote places in Asia or Africa. 

A scientific team at the Centro de Estudios Avanzados de Blanes (CEAB-CSIC) and the Estación Experimental de Aula Dei (CSIC), led by Emilio O. Casamayor, have obtained the genetic sequences of samples from 11 of these saline lakes in order to explore the microbial biodiversity. And they have found a large bunch of extremophile microbial species, new and enigmatic for science.

In the Monegros saline lakes, explains Emilio O. Casamayor, who is leading a group in the Department of Continental Ecology at the CEAB, microorganisms live adapted to very hard conditions: high UV radiation doses, extreme changes of temperature (from 10 Celsius degrees below zero up to 40 degrees), 10 times more salt concentration than sea water, high levels of magnesium and sulphur, and intense dryness.

The genetic sequences obtained showed a high biodiversity. Many of them match with sequences registered in GenBank, the biggest genetic data base in the world, which means that they are related at specie or gender level. But up to 35% of the genetic sequences obtained in the Monegros Desert don’t match with anything known: they could be, then, new species for science.

Two universal genes

Scientists have focused their work on three groups of microorganisms: archaea, bacteria and  protists. Firstly, they used filters with pore size 25 times smaller than a millimeter, to retain and separate larger organisms, such as zooplankton and algae.

Afterwards, to identify the genetic sequences, scientists have used two genes as markers, 16S and 18S rRNAs. These two universal genes can be found in the RNA of all known living beings. With the two markers, scientists have obtained consistent genetic sequences, which have afterwards been compared to the ones registered in GenBank, in order to find out how similar they are. When at least the 97% of the genetic information of two sequences is the same means, generally, that both are of the same species.

“If this identity value is below 97%”, points out Emilio O. Casamayor, “it means that they are different organisms. In our study we found many sequences whose identity value is between 90% and 97% and other sequences with an identity value is even below, at 85%, which implies that they are totally new sequences”. With these results, explains Casamayor, “we think that 35% of the microbial diversity in the Monegros salines must be new for science and it might even contain new classes and new orders of fungi, green algae or archaea”.

Scientists calculate that in a teaspoon full of water from the salines up to 10 million microorganisms can be  found

Scientists calculate that in a teaspoon full of water from the salines up to 10 million microorganisms can be  found. Some microbial populations analyzed have their nearest relatives in the  Artic and Antarctic; others, in the remote Asiatic steppes. And in some cases, they are species that have independently evolved from their relatives in the sea or freshwaters.  

Biotechnological applications

The microbial world of Monegros hides many surprises. However, scientists admit that it is too early to say what can be obtained from there. “It is not until you have the microorganisms isolated and cultured that you can clearly identify its metabolic characteristics and think about potential applications”.

Nevertheless, there are examples that show how extremophile microorganisms are an interesting source of biotechnological applications. The most emblematic , explains Casamayor, is the Taq DNA polymerase, which is used for amplifying in vitro genetic sequences. This enzyme was found out and isolated from an extremophile bacteria, Thermus aquaticus, capable of living in hot springs at more than 75 C.

Another example can be found in the lipases and protease enzymes, which are very active at cold temperatures. They were isolated from bacteria that live at very low temperatures and that can degrade fats or digest proteins. On the one hand, these proteases can be applied to the development of soaps to wash with cold water or for the leather industry. On the other hand, the lipases have a millionary market of commercial applications in several fields: polymers and biodiesel synthesis, drugs, cosmetics, agrochemical products and food additives production

The Monegros Desert, says Emilio O.Casamayor, “is an exceptional natural laboratory, that has an outstanding relevance for scientific and biotechnological research, and for studying possible life strategies on other planets. The Monegros Desert must be preserved”.

Casamayor, Emilio O., Triadó-Margarit, Xavier Castañeda, Carmen.  Microbial biodiversity in saline shallow lakes of the Monegros Desert, Spain. FEMS Microbiology Ecology : 1-16 (2013) DOI: 10.1111/1574-6941.12139