Strains-producers of bacteriorhodopsin
Construction Strain-Producers of Bacteriorhodopsin and Its Analogs
Tech Area / Field
- BIO-IND/Industrial Biotechnology/Biotechnology
- BIO-CGM/Cytology, Genetics and Molecular Biology/Biotechnology
3 Approved without Funding
Institute of Genetics and Selection of Industrial Microorganisms, Russia, Moscow
- University of Amsterdam, The Netherlands, Amsterdam\nSogang University / Department of Chemical and Biomolecular Engineering, Korea, Seoul
Project summaryProject Objective: Construction of Halobacterium salinarum strains as a promising source for the industrial production of purple membrane preparations, bacteriorhodopsin and its isotope-labeled analogs.
Halophilic bacteria Halobacterium spp. possess a unique biosystem, converting solar energy into electrochemical energy. Bacteriorhodopsin (BR) is a key element of this natural system. BR is a retinal-containing protein of the purple membranes of halobacteria.
Experts in advanced applied biotech research, in particular, nanotechnology, emphasize a dramatic growth in the amount of funding allocated to such studies [Research Review, 2002, 15(2)]. In the estimate published by the Journal Nanotechnology the cost of such research activities, performed in the U.S. since 2000, has exceeded $US 2 billion. And the increment rate of venture capital investments in nanobiotechnology in the last two or three years has achieved 313%. This area of science is also considered as the most promising for long-term capital investments [Nanotechnology, The Nanotech Report, 2003]. German experts, referring to the US Int. Trade Commission, state that the international market of BR comprises about $US 43-61 billion [www.archiv.ub.uni-marburg.de]. Germany is known for the most active studies of bacteriorhodopsin application areas, in particular, in the protection of securities against counterfeiting [mpg.de/dokumentation/pressemitteilungen/].
Thus, in the last years some evidence has been obtained that halobacteria could be put on the list of industrial microorganisms as bacteriorhodopsin producers. Based on our data, the world practice has no industrial technology of continuous cultivation of halobacteria for bacteriorhodopsin production, while the available laboratory techniques for the production of this protein are capable to generate this product only in a gram scale. Strong arguments have been generated to demonstrate that the introduction of purple membrane preparations of halobacteria (containing bacteriorhodopsin in high concentration and in the condition, applicable for bioelectronic devices) to the world market will f a c i l i t a t e completion of the relevant studies and development of commercially available instruments. Thus, a successful project implementation would advance bacteriorhodopsin production that will undoubtedly attract consumers in the world market.
The potential areas of BR application are impressively perse. They include a double-side holographic memory, ultra-fast random access memory (RAM), spatial light modulation, non-linear optic filters, recognition systems, high-contrast displays, optic switches, and picosecond detectors. Bacteriorhodopsin is also used in the production of materials, protecting securities against counterfeit and as antioxidants in medicine, pharmacy, and cosmetology.
Currently, halobacterium strains, capable to produce BR, are primarily used in the laboratory conditions mainly for research purposes. It is known from the literature that inpidual attempts were made to launch semi-industrial production of BR. However, no strains have been developed which meet all the requirements for the industrial strains-producers. In our opinion, the industrial strains of halophilic bacteria should be characterized by the enhanced efficiency of nutrition, high growth rate, and the maximal level of accumulation of the key target product – bacteriorhodopsin.
The following tasks should be solved to meet the stated objective:
1. To review factors, restricting growth and accumulation of the biomass of H. salinarum in the course of their massive cultivation.
2. To select H. salinarum strains, characterized by the highest production rates. As source strains, promising for practical applications, it will be possible to use wild H. salinarum strains and several strains with mutations of the structural gene of bacteriorhodopsin (bop).
3. To construct H. salinarum strains with the constitive level of BR synthesis (i.e. to replace its own light-, oxygen-dependent regulating elements with other components, independent on these factors and having a high level of expression of the target protein).
4. To clone structural bacteriorhodopsin gene bop of H. salinarum in Bacillus sp. cells under the altered regulation, ensuring the highest level of production and secretion of the target protein.
In general, this project is designed as a multi-faceted microbiological research, building a platform for the development of a high-efficiency biotech production of the light-sensitive protein of halobacteria - BR, a basic component of perse bioelectronic instruments. The logical outcome of project implementation could imply commercial applications of its results.
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