Deserts can be either hot or cold according to their geographical location, leading to the evolution of extremophilic organisms which are adapted to withstand such hostile living conditions. Here, we explore some of the potential industrial biotech applications of desert microbes, from bioremediation of pollutants such as PCP, to the investigation of novel anti-cancer compounds.

New desert microbial strains are being discovered all the time by research teams across the world. Dubbed ‘extremophiles’, these have developed a tolerance to high salinity (i.e. halophiles), dehydration and drastic pH and temperature changes, which would otherwise kill non-extremophiles.

Halophiles are organisms which grow in high salt (NaCl) concentrations (Source: Heiko Patzelt)

Halophiles are organisms which grow in high salt (NaCl) concentrations (Source: Heiko Patzelt)

Adaptations that permit microbes to do this are attributed to a pool of enzymes, metabolites and biomolecules which are just waiting to be mined and exploited by the biotech industry. These natural and remote landscapes could therefore be the key to solving food agricultural issues caused by global climate change; such as the ‘desertification’ and drying up of arable lands.

In a pan-European collaboration, a team from Liebniz-Institut DSMZ (Germany) and the IFAPA in Seville (Spain) found a multi-tolerant Actinomycete bacteria on a marble outcrop in the Namibian desert. This actinobacterial strain had very interesting capabilities, such as survival in the presence of high heavy metal concentrations, excessive UV radiation, metalloids and hydrogen peroxide…practically indestructible!

Other research teams have been looking for similar super-extremophiles like Actinomycete across worldwide deserts. For example, the Khesssairi et al. group from Tunisia investigated the potential of a halotolerant actinobacterium (Janibacter sp.) which was able to degrade pentachlorophenol (PCP) in a high saline environment with an extreme pH. Since PCP has been a commonly used disinfectant and pesticide since the 1930s, its accumulation in the environment has caused considerable damage to ecosystems and human health due to its toxicity.

Results show the bactieria was able to continue to metabolise PCP at consistently high rates at very low (pH 4) and high (pH 9) conditions - an effective extremophile. (Source: Khesssairi et al.)

Results show the actinobacterium was able to continue to metabolize PCP at consistently high rates at very low (pH 4) and high (pH 9) conditions – an effective extremophile. (Source: Khesssairi et al.)

Desert-derived microbes could therefore be used as a natural form of pollution control (bioremediation) for which extremophiles have long been investigated. Another example of this is the investigation of using the acid-tolerant yeast Yarrowia lipolytica in the metabolism of tri-nitrotoulene (TNT) residues left over from detonation of explosives.

If extremophilic microbes can be used to digest organic molecules as specific as bomb-residue TNT and pesticides like PCP, then what other biotech applications await discovery in desert extremophiles?

How about pharmaceutical and medical applications? A University of Warwick (UK) group collaborated with the Algerian University of Houari Boumediene (USTHB) on a paper by Selama et al. screening for useful compounds in microbe communities from Saharan desert soil samples. The team discovered up to 13 novel haloalkalitolerant and haloalkaliphilic bacteria, which had also had genes for putative anti-tumor and antimicrobial compounds of potential use in medicine.

Cultures for the 3 strains collected from Saharan soil in Algeria, investigated for putative anti-tumor metabolites. (Source: Selama et al.)

Cultures for the 3 strains collected from Saharan soil in Algeria, investigated for putative anti-tumor metabolites. (Source: Selama et al.)

So, the hidden potential of desert microbial strains are clearly under-explored by the biotech industry, and more effort should be dedicated to exploiting the natural resources of these extreme environments.

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