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Inhospitable niches are a rich source of extremozymes

At first sight, nothing much seems to grow in either the Namib desert or the Antarctic. However, a closer inspection of the ground a few centimetres below the surface reveals an enormous diversity of organisms. Industry is well aware of this rich source of microorganisms that have something to offer on the molecular level as well as for use in technical applications. So-called extremozymes have long been popular ingredients in cosmetics, detergents and medicines. However, little is yet known about their properties and application potential. Prof. Dr. Christoph Syldatk and his team from the Karlsruhe Institute of Technology (KIT) are involved in the search for biochemical exotics and are extremely enthusiastic about what remains to be discovered.

Salt stone from the Namib desert where a broad range of different extremophilic (halophilic in particular) bacteria lives. © Prof. Dr. Christoph Syldatk

“We had been driving for hours through the hostile desert,” said Prof. Dr. Christoph Syldatk from the Karlsruhe Institute of Technology (KIT), “when all of a sudden we came across some hot springs that had these fascinating stone formations made out of exotic salts along the edge. We broke one of the stones apart and discovered these amazing microbes inside.” Syldatk and his team from the Institute of Bio- and Food Technology at KIT are looking for new metabolic products in so-called extremophilic microorganisms which might be of interest in industrial applications. Extremophilic bacteria and unicellular fungi are not only found in hot salty springs, they are also found in desert soil, the depths of the oceans and the Antarctic. The researchers from Karlsruhe have been working with other researchers from around the world for quite some time on investigations into the broad range of life forms at extreme locations in an effort to find potential applications in the cosmetics, food, pharmaceutical and detergent industries.

Cold washing cycles and the production of exotic amino acids

Two of the academic research groups the KIT researchers are working with are from Cape Town in South Africa. The researchers in Cape Town led by Prof. Dr. Stephanie G. Burton and Prof. Dr. Don Cowan specialise in research into the microbial diversity of the Antarctic and the Namib desert. They collect stone and ice samples in order to determine which bacteria live in them. They screen the genomes of the species and submit the information to gene databases, grouped according to the habitats in which they live. “The databases are rich sources of information for us and other researchers around the world,” Syldatk said, going on to add, “with the techniques that we have established in our laboratory we are able to look for molecular structures that display enzymatic activities.” The Karlsruhe researchers also have bioreactors where they can grow bacteria that are able to survive at low temperatures and grow in nutrient media that contain specific lipids. “We are looking for Antarctic bacteria with enzymes that are able to break up lipids at low temperatures. These enzymes could then be used as ingredients in a new generation of detergents for washing clothes at temperatures below 30°C, which would considerably reduce energy consumption,” said Syldatk.

A few years ago, working with partners from England the researchers from Karlsruhe managed to isolate and investigate enzymes from deep sea organisms of the genus Rhodococcus. These bacteria can cleave toxic nitriles and are thus suitable for the production of unusual amino acids that can be used as precursors for semisynthetic antibiotics. This collaboration, which was funded by the chemical giant Evonik Industries GmbH (formerly Degussa AG), has led to the development of concrete process technologies for use in industrial applications. The list of interesting substance groups is rather long. It includes lipases which catalyse the cleavage of fats and oils, as well as enzymes that produce emulsifiers and stabilisers for use in cosmetics and sanitary products. The list also includes biosurfactant precursors that have the potential to be used in degradable detergents and washing-up liquids.

Gigantic gene databases and high-throughput screening

Syldatk and his team are popular partners for industry mainly due to the broad range of methods they have available in their laboratory: they culture microorganisms with interesting properties, prepare substance mixtures, develop methods that enable them to immobilise enzymes on different carrier substrates and examine them in greater detail, as well as developing process management strategies. As basic researchers, the Karlsruhe scientists also look at the molecular level: which structures enable an enzyme isolated from a particularly cold-loving bacterial species to cleave lipids at temperatures of 20°C while the homologous enzyme from a close relative requires temperatures as high as 50°C to catalyse the same reaction?

The researchers led by Prof. Dr. Christoph Syldatk (first on the left) working in the Namib desert. © Prof. Dr. Christoph Syldatk

“Previously, when we wanted to look at a specific enzyme from an extremophilic species we had to cultivate the bacteria in the laboratory. However, most bacteria do not grow outside their natural habitat, so growing them in the laboratory was difficult, if not impossible,” said Syldatk. “However, we are now able to isolate the enzyme-encoding gene and grow it in E. coli, a popular model organism that is easy to grow in the laboratory.” Progress made in the fields of molecular and systems biology over the last ten years or so has enabled the researchers to carry out investigations with extremophilic bacteria that were previously impossible. It is now possible to screen large gene banks and use high-throughput methods to investigate molecular structures, which means that the researchers can work faster and more accurately. In addition, work can be divided among several research groups, as the successful collaboration with the group’s South African and English partners has shown. Extremophilic microorganisms have a lot more to offer and Syldatk is already looking forward to his next expedition to the Namib desert.

Further information:
Prof. Dr. Christoph Syldatk
Dean of the Faculty of Chemical Engineering and Process Technology 
Karlsruhe Institute of Technology (KIT)
Institute of Bio- and Food Technology
Area II: Technical Biology
Kaiserstraße 12
Building 40.11, 1. OG, Room 101.2
76131 Karlsruhe
Tel.: +49 (0)721/ 608 – 421 23 / - 421 24
Fax: +49 (0)721/ 608 – 448 81
E-mail: christoph.syldatk(at)kit.edu

Website address: https://www.biooekonomie-bw.de/en/articles/news/inhospitable-niches-are-a-rich-source-of-extremozymes/