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Extremophilic bacteria

What causes stress for some, actually speeds others like extremophilic bacteria up. They love it hot, sour or salty, toxic substances like heavy metals also do them good and even give them energy. As molecular and systems biology techniques get better and better, industry is also becoming increasingly interested in these exotic organisms. What potential does knowing the biochemistry of extremophilic bacteria have for the pharmaceutical, cosmetics and sanitary articles industries? Whatever the answer might turn out to be, there is certainly a growing trend towards using extremophilic microbes in academic and industrial research.

The preferred habitats of extremophilic microorganisms are hot springs and geysers. © www.wikipedia.org

The metabolism of bacteria and algae that live in hot volcanic springs, the Dead Sea, contaminated soils or the Arctic pack ice has adapted to extreme habitats and always manages to glean something positive from such environments. Life is able to thrive almost anywhere on Earth. The metabolism of extremophilic microorganisms generates a rich source of molecules that enable the bacteria to live in extreme, virtually inhabitable areas. Over the last few years, the biotech industry has also recognized the potential of this barely exploited “gold mine” and is in a real gold-rush mood. 

Energy-saving and sustainable 

There appears to be a fundamental change in the way industry is thinking: the industrial synthesis of numerous substance classes is now frequently done in bioreactors rather than chemical refineries. Innovative materials include basic and fine chemicals produced from plant raw materials, biopolymers used for the production of plastics, and environmentally friendly biofuels. “Biocatalyser” is the keyword of the future. Biocatalysers are enzymes produced with living organisms and which mediate defined synthesis steps. Besides being used in the production of fine chemicals, biocatalysers are also increasingly being used in the production of mass chemicals. Bioreactors of 500 m³ or more are already being used for the production of the flavour enhancer L-glutamate, the feed supplement L-lysine, antibiotics, vitamins, citric and lactic acid. 

Bioreactors are already being used for the microbial production of proteins. © Peter Grotzinger/ www.wikipedia.org

The substitution of petrochemical production steps with biotechnological methods could potentially reduce energy use and facilitate the shift to production methods that use renewable raw materials. The BMBF plans to set aside up to 100 million euros in funding for its “Industrial Biotechnology Innovation Initiative” for the next five to ten years. As molecular high-throughput methods and better cultivation methods have been developed over the last few years, academic and industry researchers have increasingly focused on the use of exotic bacteria and fungi.

Pink fish meat and UV skin protection 

Their tolerance to extreme chemical and physical environments makes the biomolecules of extremophilic microorganisms interesting for numerous industrial synthesis steps that need to be carried out at specific high or low temperatures or pressure, in the absence of oxygen or in other “exotic” chemical environments.

Extremophilic organisms have broken many records for tolerance to different conditions:

Cold: -15°C - microalgae (Eukarya)

Heat: 113°C - Pyrolobus fumarii (Archaea)

Acidic: pH 0.7 - Picrophilus torridus (Archaea)

Alkaline: pH >10 - Natronobacterium pharaonis (Archaea)

Irradiation: >3 Mrad - Deinococcus radiodurans (Bacteria)

Salt: >5 M - Halobacteriaceae (Archaea)

Thermus aquaticus is an extremophilic bacterium that thrives in hot springs and geysers. © Diane Montpetit (Food Research and Development Centre, Agriculture and Agri-Food Canada)/ www.wikipe

“Extremozymes“ function under extreme environmental conditions and are already being used for many applications. If biologists were unable to use the enzyme Taq polymerase, they would have to pipette every single PCR (polymerase chain reaction) reaction step. Taq polymerase is a Thermus aquaticus enzyme that copes easily with the elevated temperatures that are required to enable DNA strands to separate and act as templates in the next round of amplification. In addition to enzymes, other molecules inside the cells of extremophilic bacteria also play an important role in many applications. The molecule astaxanthin is responsible for the red colour of snow algae and is also an important antioxidant used in cosmetics. It is also used as a colourant in fish feed, giving fish on ice display trays their attractive pink appearance. “Compatible solutes”, which are isolated from halophilic bacteria and are able to stabilise biomolecules against stress factors, have recently entered the fields of medicine, diagnostics and cosmetics. The production of ectoine, one of the most important compatible solutes, from Halomonas elogata is already firmly established. Ectoine is used as an active ingredient in many cosmetics products and protects the skin against UV radiation.

Methane consumers and stress-free plants

Extremophilic microorganisms might in future help turn society’s vision of greater environmental protection into reality: the use of methane-consuming bacteria to counteract the greenhouse effect and thermophilic bacteria for the fermentation of green waste at temperatures of 100°C or more. In addition, a detailed understanding of the molecular and metabolic biology of extremophilic microorganisms also has the potential to help make agriculturally relevant plants more resistant to high salt concentrations, heavy metal contaminations or drought. Researchers from Baden-Württemberg and their industrial partners are already working on tapping the huge potential of extremophilic bacteria.

Where does the main potential of microbial exotics and their metabolic products lie? How can scientists discover, analyse and put enzyme systems in extremophilic bacteria to good use in numerous applications? This dossier provides insights into this potential and into possible applications to which it could be applied.


References:
Cypionka, Heribert: Grundlagen der Mikrobiologie; Springer Berlin Heidelberg (pocket book - 2010)

Groß, Michael: Exzentriker des Lebens: Zellen zwischen Hitzeschock und Kältestress; Spektrum Verlag (hardcopy edition 1997)

Glossary

  • Desoxyribonucleic acid (DNA) is a double-stranded, helical macromolecule encoding the genetic information of an organism.
  • PCR or Polymerase Chain Reaction is a biomolecular method to amplify short DNA fragments in an easy way. Therefore, merely the DNA template, an enzyme named DNA polymerase which catalyses the amplification, short complementary oligonucleotides, which serve as starting point for the polymerase and the components of the DNA, which are called desoxynucleosidtriphosphates are needed. The amplification is controlled by several cycles of temperature changes.
  • Federal Ministry of Education and Research

Glossary

  • An antibiotic is a bacteriocidal or bacteriostatic substance produced by microorganisms (bacteria, fungi) of which minute concentrations inhibit the growth of bacteria.
  • Bacteria are microscopically small, unicellular organisms belonging to the prokaryotes.
  • Biotechnology is the study of all processes involving life cells or enzymes for the transformation and production of certain substances.
  • Desoxyribonucleic acid (DNA) is a double-stranded, helical macromolecule encoding the genetic information of an organism.
  • There are two definitions for the term organism: a) Any biological unit which is capable of reproduction and which is autonomous, i.e. that is able to exist without foreign help (microorganisms, fungi, plants, animals including humans). b) Definition from the Gentechnikgesetz (German Genetic Engineering Law): “Any biological unit which is capable of reproducing or transferring genetic material.“ This definition also includes viruses and viroids. In consequence, any genetic engineering work involving these kinds of particles is regulated by the Genetic Engineering Law.
  • PCR or Polymerase Chain Reaction is a biomolecular method to amplify short DNA fragments in an easy way. Therefore, merely the DNA template, an enzyme named DNA polymerase which catalyses the amplification, short complementary oligonucleotides, which serve as starting point for the polymerase and the components of the DNA, which are called desoxynucleosidtriphosphates are needed. The amplification is controlled by several cycles of temperature changes.
  • A bioreactor is a closed system capable of supporting the growth of cells, mammalian or bacterial, in a culture medium in which a biological transformation takes place.
  • Fermentation is the process of converting biological materials with the help of microorganisms or by the addition of enzymes. In its strictest sense, fermentation is the anaerobic oxidation of sugars for the purpose of energy generation of the metabolic organism.
  • Biochemistry is the study of the chemical processes in living organisms. Therefore it touches the studies of chemistry and biology as well as physiology.
  • The toxicity is the poisonousness of a substance.
  • Plasticity is the attribute of organisms to change their characteristic values under the influence of environmental factors. Therefore, neuroplasticity is the characteristic of neurons to change their response behaviour dependent from their activity. In most cases, the strength of the synaptic transmission is influenced (synaptic plasticity). The neuroplasticity or synaptic plasticity, respectively, is considered to be the basic mechanism in learning processes and in the formation of memories.
  • L-lysine is a basic and essential amino acid.
  • The term metabolism includes the uptake, transport, biochemical conversion and excretion of substances within an organism. These processes are necessary to build up the body mass and to meet the energy demand of the body. The opposed processes of metabolism are called anabolism and catabolism. Effectiveness of several enzymes could be catabol and anabol. Within one biochemical pathway they cannot work in both directions at the same time.
  • Vitamins are essential organic compounds that have to be uptaken as food ingredients. Vitamins regulate the metabolism by enabling the recycling of proteins, carbohydrats and mineral nutrients. There exist liposoluble and watersoluble vitamins. Vitamin C, for example, supports the immune system. Exception: Vitamin D is synthesizable by the body as long as enough sunlight is available.
  • It is a hydrocarbon and therefore a chemical compund. It is scentless, achromatic and combustible. In industry it is often used as fuel gas.
  • Federal Ministry of Education and Research
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